# Gain Structure for Home Theater Discussion Thread



## Wayne A. Pflughaupt (Apr 13, 2006)

Please use this thread for any comments or discussion about my article Gain Structure for Home Theater.

Regards,
Wayne


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## laser188139 (Sep 19, 2009)

*re: Gain Structure for Home Theater: Getting the Most from Pro Audio Equipment in Your System*

Hello Wayne,

It's great of you to write this article on such an interesting subject. 

You might want to add to this what the impact is of using an AVR with a built-in equalization system such as Audyssey. I've thought about this a little in terms of my Denon, even though I use external amplification only for the powered sub. It strikes me that the effects come from two areas that affect the point at which clipping might occur: the AVR may have different level settings for each speaker, and the static equalization may boost certain frequencies up to 9dB. 

In Part 7, where you discuss measuring the maximum voltage from the AVR, the setting of the speaker trim might matter, especially if it was very negative. For purposes of the experiment, it might be best to set it to at least 0dB, or perhaps to its maximum positive value. 

In Part 9, where you discuss how much headroom to allow, it would be nice to allow enough headroom for the maximum boost that the equalization system might introduce, e.g., 9dB for Audyssey. This would ensure that no clipping would occur from the voltage peak. The speaker trim might come into play here, too. Obviously if one has verified that clipping does not occur with the trims set to 0dB, and if the AVRs calibration sets a higher trim to achieve reference levels, clipping might now appear. Related to this, adjusting the amplifier's gain to the highest level that avoids clipping at maximum signal affects how the AVRs volume setting is calibrated for reference levels. At this highest possible amplifier gain, you might have a situation where the AVR cannot set the speaker trim low enough to correctly calibrate the volume level. 

I don't think a system like Audyssey's DynEQ affects the discussion significantly. As you are recommending doing these procedures with the AVR's volume set to maximum, DynEQ should be providing no boost to the signal. As it might even be providing a reduction in the sub range, if it thinks the levels are above reference, it would probably be best that it be disabled. 

I also think any source level adjustment in the AVR does not affect the discussion. Assuming the user calibrates the analog source inputs to give the same volume as the digital inputs, one would hope that these will not drive the levels past the 0dBFS that was used when adjusting the gain. 

I think that exhausts my suggestions. 

Thanks for writing this,
Bill


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## soho54 (Jul 22, 2006)

*re: Gain Structure for Home Theater: Getting the Most from Pro Audio Equipment in Your System*



Wayne A. Pflughaupt said:


> I apologize for the length of this, but I figure if you’re going to scorch sacred cows you’d better have the documentation to back it up.


 I missed the documentation. Where are the distortion, noise floor, and headroom graphs, and information to back this method up?


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## Wayne A. Pflughaupt (Apr 13, 2006)

*re: Gain Structure for Home Theater: Getting the Most from Pro Audio Equipment in Your System*


Thanks for the thoughtful comments, Bill. :T




laser188139 said:


> You might want to add to this what the impact is of using an AVR with a built-in equalization system such as Audyssey. I've thought about this a little in terms of my Denon, even though I use external amplification only for the powered sub. It strikes me that the effects come from two areas that affect the point at which clipping might occur: the AVR may have different level settings for each speaker, and the static equalization may boost certain frequencies up to 12dB.





> In Part 9, where you discuss how much headroom to allow, it would be nice to allow enough headroom for the maximum boost that the equalization system might introduce, e.g., 12dB for Audyssey. This would ensure that no clipping would occur from the voltage peak. The speaker trim might come into play here, too. Obviously if one has verified that clipping does not occur with the trims set to 0dB, and if the AVRs calibration sets a higher trim to achieve reference levels, clipping might now appear.


Yeah, good point about Audyssey. Didn’t even consider it, because I don’t use it. But I don’t really see any issues with it WRT my home-grown gain-setting process. Maximum clean pre amp output is the maximum usable output, whether or not Audyssey’s EQ is there or not. I assume that the AVR manufacturers that incorporate Audyssey into their receivers have taken care of all that. I did note that if people were concerned about pre amp headroom when setting the amp gains, they can use a lower AVR volume setting than max. Seems to me that should be sufficient. :T

*EDIT:* Part 9 has been re-worked to cover Audyssey and other auto-EQ features, as well as outboard equalization.




> In Part 7, where you discuss measuring the maximum voltage from the AVR, the setting of the speaker trim might matter, especially if it was very negative. For purposes of the experiment, it might be best to set it to at least 0dB, or perhaps to its maximum positive value.


Right. And I did recommend setting speaker levels to their highest setting in the 3rd paragraph under the “How to determine your AVR’s output voltage: _“My AVR has all speaker-level settings referenced to the main left and right channels, which are fixed and cannot be adjusted in the menu. If your AVR allows for adjustments for the front left and right channels, they should be set to maximum for this exercise, as should the center channel and subwoofer if you intend to measure those too.”_




> Related to this, adjusting the amplifier's gain to the highest level that avoids clipping at maximum signal affects how the AVRs volume setting is calibrated for reference levels. At this highest possible amplifier gain, you might have a situation where the AVR cannot set the speaker trim low enough to correctly calibrate the volume level.


I expect this would only be an issue if someone was mixing high- and low-efficiency speakers in their system. It would be the efficient speakers that would be dialed back in the AVR. But since efficient speakers don’t need much power, it might not matter. If it did – dialing the AVR speaker levels back would mean the amp gains could be ratcheted up to compensate. Alternately, the speaker adjustments could just be performed via the amp gains instead of the AVR menu.


Regards,
Wayne


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## Wayne A. Pflughaupt (Apr 13, 2006)

*re: Gain Structure for Home Theater: Getting the Most from Pro Audio Equipment in Your System*




soho54 said:


> I missed the documentation. Where are the distortion, noise floor, and headroom graphs, and information to back this method up?


 Relevant graphs were presented in Parts Three and Five. Perhaps not everything you're looking for was included, but it's far more graphs and documentation than you'll find in the typical PA system gain structure article. 

I don’t have a problem answering some of the question you edited out of your post. I don’t think this topic as it relates to home theater has ever examined in depth before, so it’s natural that people will have questions and concerns. I tried to be thorough, but I doubt I thought of everything.




> It is also possible/common to get higher than what should be 0dBFS out of, well pretty much everything.


Well, it’s the maximum a DVD disc itself will put out, as it’s a digital media and will not support a higher level without distortion. I assume the DVD manufacturers are aware of that and will make sure the audio on their discs does not go beyond 0 dBFS and distort. 0dBFS is also the maximum a DVD player will output, since a digital output it’s passing the signal straight along to the AVR. I assume the same can be said about things like cable TV and sat receivers as well. 

It is a bit different with an AVR, of course, since the pre-amp outputs are Vrms. But it would require source component connected to the AVR with a hotter signal than 0 dBFS to get more output from it than would be provided with a DVD player or similar media component. I can’t imagine what that would be, unless someone’s plugging their Behringer XENYX mixer to their AVR. If you want to count something like that, then you’re correct: It’s possible to get higher than a 0 dBFS signal. But by and large setting amp gains with the signal generated by the 0 dBFS signal source is perfectly sufficient.




> There are a couple of other explanations that seem a bit off as well, form a pro audio mindset.


And that’s perfectly fine. This is not pro audio. This is home theater. The problem people have been having is thinking the “pro audio mindset” somehow became relevant to them when they added a piece of professional equipment to their home theater system. As thoroughly discussed in Part 2, a pro audio-styled gain structure protocol does not necessarily cross-reference to home audio.




> This "Make sure all speaker-level settings in the AVR's menu are set to max," is just bad advice. It is the flaw behind the whole thing. An AVR like any other device has a set operational range, and headroom built in.


The “set speakers to max” thing is only for the purposes of setting the amp gains. After that you’re supposed to adjust the relative speaker levels as it’s normally accomplished, with the AVR’s rotating pink noise sound, a calibration disc, etc. Headroom is restored when you turn everything back down and use the system as normal. You weren’t running your system wide open before gain-structuring, and you won’t be afterwards.

But it’s imperative to have the maximum signal on tap when setting the amp gains. Otherwise you will end up with the gains being set higher than they need to be, which can lead to more noise from the amp than you’d get with lower gain settings. 

Besides, my “maximum clean level” procedure for setting amp gains is virtually identical to what Rane outlines in their gain structure article, which I linked in Part 2. Have you read it?

Regards,
Wayne


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## GranteedEV (Aug 8, 2010)

*re: Gain Structure for Home Theater: Getting the Most from Pro Audio Equipment in Your System*

So the gyst of it is...
I need to find not only a HPF and DSP for my sub, but has to be a low noise HPF and DSP?
_Great._


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## Wayne A. Pflughaupt (Apr 13, 2006)

*re: Gain Structure for Home Theater: Getting the Most from Pro Audio Equipment in Your System*


Not really, noise from substandard components is virtually no issue with sub woofers because it is not audible. This is why you’ll hardly ever see noise specs of any kind for manufactured subs. Sorry for not clarifying that, I’ll make the necessary changes to the text.

By the way, unless you are bottoming out your sub, or driving the amp to clipping, you don't need a high pass filter.

Regards,
Wayne


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## Sonnie (Apr 11, 2006)

*re: Gain Structure for Home Theater: Getting the Most from Pro Audio Equipment in Your System*

Fine and outstanding article... :clap:


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## soho54 (Jul 22, 2006)

*re: Gain Structure for Home Theater: Getting the Most from Pro Audio Equipment in Your System*

I edited them out because I felt the questions would turn things into a line by line discussion, and I have no desire to do that. I have been down this road many times, and this does not seem like the proper place. That was me, stepping out quietly.



Wayne A. Pflughaupt said:


> Relevant graphs were presented in Part Three. The “sacred cow” I was referring to was the popular maxed-out signals canard. I’ll go back and change the text to make better sure the point is made.


I still do not follow then. You say that which is true as structures gain has nothing to do with maxed-out signals, and later add "


> Gain structure is merely an exercise to insure that the pro amps are getting enough signal to drive them to maximum output.


" this is not so accurate. The idea is to pass the *cleanest* signal possible along the signal chain. Live sound extends this to the amps, but that is to protect fidelity, and equipment as well. It is not for the sake of getting maximum output.




Wayne A. Pflughaupt said:


> OdBFS is also the maximum a DVD player will output, since a digital output it’s passing the signal straight along to the AVR. I assume the same can be said about things like cable TV and sat receivers as well.


 0dBFS on a disk has a fickle relationship with what you end up with out of the AVR analogue outputs. +0dBFS signals are very common, and are produced by the DAC conversion, bass management, and the master volume control alone, and as a group. There are also oddities with some devices and 0dBFS signals as well where 0dBFS may not be as loud as signals just a few dB lower in intensity. Most every commercial CD released in the last half a dozen years can produce +0dBFS. It's even worse with most mp3s. No one is ripping DVDs in raw format, but I see no reason for it not to be the similar.




Wayne A. Pflughaupt said:


> And that’s perfectly fine. This is not pro audio. This is home theater. The problem people have been having is thinking the “pro audio mindset” somehow became relevant to them when they added a piece of professional equipment to their home theater system. As thoroughly discussed in Part 2, a pro audio-styled gain structure protocol does not necessarily cross-reference to home audio.


 If you put a piece of differently referenced gear into your signal chain, it is now relevant. Structure, protocol, terms, have nothing to do with it. It is basic electronics. Home gear runs on the exact same base principles pro gear does. Once you add a device that does not conform to the same default "home" reference, it pays to think about the things home audio takes for granted as a given.




Wayne A. Pflughaupt said:


> The “set speakers to max” thing is only for the purposes of setting the amp gains. After that you’re supposed to adjust the relative speaker levels as it’s normally accomplished, with the AVR’s rotating pink noise sound, a calibration disc, etc. Headroom is restored when you turn everything back down and use the system as normal. You weren’t running your system wide open before gain-structuring, and you won’t be afterwards.
> 
> But it’s imperative to have the maximum signal on tap when setting the amp gains. Otherwise you will end up with the gains being set higher than they need to be, which can lead to more noise from the amp than you’d get with lower gain settings.
> 
> Besides, my “max level” procedure for setting amp gains is virtually identical to what Rane outlines in their gain structure article, which I linked in Part 2. Have you read it?


Starting at the end... If you look at part 4 in the Setting Power Amplifiers section, you see that you need to identify the max clean signal from everything up until that point first. SOP. Just turning up the levels to max isn't the way to go. Most AVR outputs will be distorting and clipping before the max anyway, so it's kind of arbitrary. You will clip the amp before the input sensitivity voltage is reached. You are tying to get around clipping the amp by raising the AVR to levels it should never normally encounter, but doesn't this still leave the amp "with the gains being set higher than they need to be?" This leaves the amount of gain the AVR can add to a channel out of the mix. With 12dB you should be alright, but what about models with only 6dB?

What happens when the same AVR and amp are used in two setups with one having low sensitivity speakers, and the other high? What happens when you switch out an amp of higher/lower power? Now add a Pro EQ, and run though again? Which one was the optimal setup?

It seems like setting up from the end of the signal chain to the front.


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## Wayne A. Pflughaupt (Apr 13, 2006)

*re: Gain Structure for Home Theater: Getting the Most from Pro Audio Equipment in Your System*




soho54 said:


> I still do not follow then. You say that which is true as structures gain has nothing to do with maxed-out signals, and later add "
> 
> 
> > Gain structure is merely an exercise to insure that the pro amps are getting enough signal to drive them to maximum output.


The discussion on the home audio forums, as least what I’ve seen in the past ten years, has been that pro gear requires a +4 dBU signal, and if you can’t get that from your home theater pre amp/AVR you’re going to have noise, reduced dynamic range, etc. In most cases it’s possible to drive a pro amp with a consumer front end, especially if one is chosen with an ample sensitivity rating.




> 0dBFS on a disk has a fickle relationship with what you end up with out of the AVR analogue outputs. +0dBFS signals are very common, and are produced by the DAC conversion, bass management, and the master volume control alone, and as a group. There are also oddities with some devices and 0dBFS signals as well where 0dBFS may not be as loud as signals just a few dB lower in intensity. Most every commercial CD released in the last half a dozen years can produce 0dBFS.


 You’re “mixing and matching” the digital dBFS scale with the analog Vrms scale. 0 dBFS is the highest possible digital signal; there is no such thing as “+0dBFS.” If a component somehow adds some boost to the signal in the analog domain (i.e. after the digital-to-analog conversion), that’s of no relevance. The measurable-voltage signal at the AVR’s main pre outputs will reflect that, and any voltage measurement will still be valid.




> If you put a piece of differently referenced gear into your signal chain, it is now relevant. Structure, protocol, terms, have nothing to do with it. It is basic electronics. Home gear runs on the exact same base principles pro gear does. Once you add a device that does not conform to the same default "home" reference, it pays to think about the things home audio takes for granted as a given.


There is a long and established history on the home audio forums that trying to apply a pro-audio-styled gain structure protocol has caused a lot of confusion, if not out-and-out problems, such as we see here in this post from another Forum: 

> I was considering a DCX2496 but had worries about three things. First, the pro level; second, how to get a full signal to the DCX for good digitization (i.e. keep the volume control after the digitization to avoid digitizing a signal 50 dB below max) ...


As another example I recall at least one thread at AVS I came across while researching this, of a guy who had added a Behringer DCX2496 to his system. Following the pro audio protocol, he’d managed to get his levels hot enough to get a good reading on the DCX input meters (forget how he accomplished that). The result: An added 6 dB of noise (by his account), and problems clipping the inputs of his home audio amplifiers. Then there was the case I linked at the end of the article.

Sure, it “it pays to think about the things home audio takes for granted as a given.” For instance, a couple of the things home audio has always taken for granted is quiet noise floors and not having to jack around with amp gains. IMO the main thing to be aware of is system compatibility – i.e. making sure the home and pro gear chosen is compatible. Such as not trying to use an amp with a higher sensitivity voltage than your AVR can generate. Or the possibility that cheap pro gear may add a lot of background noise. Hopefully with this piece people will now be able to determine where the weak link is in their signal chain, if there is one. 




> Starting at the end... If you look at part 4 in the Setting Power Amplifiers section, you see that you need to identify the max clean signal from everything up until that point first. SOP. Just turning up the levels to max isn't the way to go. Most AVR outputs will be distorting and clipping before the max anyway, so it's kind of arbitrary. You will clip the amp before the input sensitivity voltage is reached. You are tying to get around clipping the amp by raising the AVR to levels it should never normally encounter, but doesn't this still leave the amp "with the gains being set higher than they need to be?" This leaves the amount of gain the AVR can add to a channel out of the mix. With 12dB you should be alright, but what about models with only 6dB?


 I expect people have the good sense to know if they are getting distortion and can easily tweak things to get the desired results. As I’ve noted more than once, anyone worried about the pre-outs clipping can easily use a lower setting for gain structuring.




> What happens when the same AVR and amp are used in two setups with one having low sensitivity speakers, and the other high? What happens when you switch out an amp of higher/lower power? Now add a Pro EQ, and run though again? Which one was the optimal setup?


I would hope that people would have the good sense to re-calibrate if they make equipment changes. Not sure why you expect that they wouldn't.

It’s impossible for me to conceive of or address every scenario in existence. However, following my suggestions HT enthusiasts hopefully have the tools to determine for themselves what their system needs. 

*EDIT:* In light of your concerns about not addressing systems with low sensativity speakers etc., and Bill's comments along the same lines in his post, I've added new text to Part 9 to clarify that my suggestions are general in nature and cannot possibly address every system configuration in existance. I’ve also added text to cover gain structure with both outboard equalizers and auto-EQ systems like Audyssey. Thanks for bringing these things to my attention. :T

Regards,
Wayne


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## soho54 (Jul 22, 2006)

*re: Gain Structure for Home Theater: Getting the Most from Pro Audio Equipment in Your System*

Let me get a little long winded here. 

The point you seem to be trying to make is that most AVRs should be able to run a proamp to maximum power with no problems. This is true for most AVRs, especially for AVRs in the middle up range. The problem over the years has been one group that thinks there is never a situation where an AVR can't drive a pro amp properly, another group that has decided no AVR can drive a pro amp properly, and the group of newbies who can't tell who to believe. Do they trust one of these two, or the other guy saying try it out, if it doesn't work add a converter.

The issues with Pro signal processing gear added in is another nut altogether.



Wayne A. Pflughaupt said:


> The discussion on the home audio forums, as least what I’ve seen in the past ten years, has been that pro gear requires a +4 dBU signal, and if you can’t get that from your home theater pre amp/AVR you’re going to have noise, reduced dynamic range, etc.


 Unfortunately, it is true. That doesn't mean it can't work fine that way, but to say it is anything but true is just wrong. Of course you have to understand what +4 dBu is.

Most Pro gear is set up to operate in it's optimal range at 1.228volts balanced (*+4 dBu or 0 Vu*.) This is not the ceiling though. It is not like 0dBFS on a DVD. This is the nominal signal. It would be like -20dB in the film world (_-30dB is the HT equivalent._)

Now lets say the balanced device has an input ceiling of +22dBu (very common,) and your unbalanced out can only do 5v max clean (_a common LFE out number._) +22dBu is 10v, so you are 6dB closer to the noise floor than you should be, and have lost 1bit of resolution. If this was a signal processor, and you connected it to a consumer unbalanced amp you just lost another 6dB do to the conversion. 

This brings up another thing that is mis-stated all the time. You automatically lose 6dB of headroom and gain going from balanced to unbalanced (_unless you have a special cross-coupled output, then you just lose headroom and not gain_ :dumbcrazy not the other way around.




Wayne A. Pflughaupt said:


> You’re “mixing and matching” the digital dBFS scale with the analog Vrms scale. 0 dBFS is the highest possible digital signal; there is no such thing as “+0dBFS.” If a component somehow adds some boost to the signal in the analog domain (i.e. after the digital-to-analog conversion), that’s of no relevance. The measurable-voltage signal at the AVR’s main pre outputs will reflect that, and any voltage measurement will still be valid.


I was just trying to show that 0dBFS is not always something that scales properly with the rest of the signal. The voltage jump from -10dBFS to 0dBFS could be 10dB, 16dB, or 5dB because of the 0dBFS+ (_I was improperly using +0dBFS before_) conditions present in all digital to analogue systems. 0dBFS is absolute on the disk, but ones it leaves all bets are off. This is part of the reason why digital test signals are sent a -20dBFS to -10dBFS.

For a clean reference signal (_assuming a fully digital connection up to the AVR,_) a -6dBFS peak sine should avoid all the Nyquist headache for a single channel test. You would just bump the master volume +6dB to compensate, as this is done after the digital section. For an LFE test you would want an identical -6dBFS wave on the LFE+L+R channels, and use bass management to send everything to the sub out. This will just fill the 5dB digital headroom in the DD processor, and allow a full strength signal out of the preout with the master volume at +6.

This is without getting into distortion levels. Such as, my AVR at 0mvl(_corrected_) will begin to audibly distort with a simple LFE channel signal of 0dBFS(_corrected_) without redirected bass with a channel level gain of +4dB of +12dB possible. You can test this with software that has loopback capability, or adjust the power amps sensitivity so that it is only 80dB in-room instead of 120 something. I also found that around +8dB I started to get premature clipping from my amp. Unfortunately, you can not register distortion/clipping with a DMM. It requires measurement.



Wayne A. Pflughaupt said:


> There is a long and established history on the home audio forums that trying to apply a pro-audio-styled gain structure protocol has caused a lot of confusion, if not out-and-out problems. As an example I recall at least one thread at AVS I came across while researching this, of a guy who had added a Behringer DCX2496 to his system. Following the pro audio protocol, he’d managed to get his levels hot enough to get a good reading on the DCX input meters (forget how he accomplished that). The result: An added 6 dB of noise (by his account), and problems clipping the inputs of his home audio amplifiers. Then there was the case I linked at the end of the article.


That is not how a professional would do it though. :bigsmile: There should be zero clipping. Clipping takes precedence over DNR. He bumped up his levels to get the most DNR out of the signal processor, only to overdrive his -10 dBV amp inputs. He should have accepted the DNR loss through the DCX, or added another line converter after it to reverse the one before.




Wayne A. Pflughaupt said:


> I expect people have the good sense to know if they are getting distortion and can easily tweak things to get the desired results.


 Those people wouldn't need to read this to know how to set things up.  The point of structured gain is to never get to the distortion/clipping level, but also maximize DNR of the total system. You can miss the distortion/clipping level, and still have lowered your DNR.


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## lcaillo (May 2, 2006)

*re: Gain Structure for Home Theater: Getting the Most from Pro Audio Equipment in Your System*



soho54 said:


> Now lets say the balanced device has an input ceiling of +22dBu (very common,) and your unbalanced out can only do 5v max clean (_a common LFE out number._) +22dBu is 10v, so you are 6dB closer to the noise floor than you should be, and have lost 1bit of resolution.


I would suggest care in how you describe this. Talking about 1 bit of resolution in analog domain is like talking about IRE in digital video. That bit is not getting lost as resolution, but the dynamic range is diminished by the equivalent effective range. It is picking nits, but Wayne's goal here is to have a reference document that is factually correct and your posts are surely a big help in the constant process of revision and better targetting the discussion. It merits being correct and consistent in the application of terminology.



soho54 said:


> That is not how a professional would do it though. :bigsmile: There should be zero clipping. Clipping takes precedence over DNR. He bumped up his levels to get the most DNR out of the signal processor, only to overdrive his -10 dBV amp inputs. He should have accepted the DNR loss through the DCX, or added another line converter after it to reverse the one before.
> 
> Those people wouldn't need to read this to know how to set things up.  The point of structured gain is to never get to the distortion/clipping level, but also maximize DNR of the total system. You can miss the distortion/clipping level, and still have lowered your DNR.


Remember that most of the people who will be making use of the document are not professionals but HT enthusiasts who need to better understand how to intgegrate consumer and pro equipment. The reason that this is all quite important is precisely that most do not understand gain and its relationship to SNR.

Your posts are very helpful, so don't consider my comments to be purely critical. I simply want to make it more likely that the general reader gets the point. In my area of greater interest, video calibration, we run into similar issues all the time. No professional nor professional monitor would ever be set up to crush whites nor blacks, and the concept of dynamic range within the capability of the device is well understood. When we cross over to consumer products that are set up from the factory to "clip" all the time, it becomes difficult to educate the masses in a clear manner. The issue of digital vs analog terminology and differences in their signal levels that I mentioned above is a constant example of the confusion that can occur.


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## Wayne A. Pflughaupt (Apr 13, 2006)

*re: Gain Structure for Home Theater: Getting the Most from Pro Audio Equipment in Your System*


Yes, your comments have been very helpful, soho. 

Re your concerns about the ”oddities with some devices and 0 dBFS signals.” Actually that very issue was kind of nagging at me in the back recesses of my brain when I was writing, that we probably can’t expect absolute uniformity from everything from HTIB’s and high end gear. Unfortunately it never burst through to see the light of day. :laugh:

Nevertheless, I still don’t see any reason to think we should be concerned about using a 0 dBFS signal for a gain structuring exercise. I assume that the consumer hardware manufacturers are already calibrating A/D converters with some headroom, just as the pro manufacturers do. On top of that, I’m sure that post production and software manufacturers will top out their DVDs below 0 dBFS. My main concern is that the reference signal needs to equal or exceed the maximum that can be expected from the media. It should not be appreciably lower than what’s expected from the media.




> The issues with Pro signal processing gear added in is another nut altogether.
> 
> Unfortunately, it is true [that operating pro gear at less than +4 will cause added noise and reduced dymanic range]. That doesn't mean it can't work fine that way, but to say it is anything but true is just wrong. Of course you have to understand what +4 dBu is.
> 
> ...


Basically you're re-stating the tired max-levels theory, which I've sufficiently debunked as bogus. Pro gear, just like consumer, can be operated at any signal level, and a high or low level does not change the noise floor of the component in question. The component’s noise floor is fixed. It’s _not_ going to increase, even if you reduce the signal down to the level of background music, or even to zero. 

It's simply not necessary for the upper signal limits of pro audio to be reached in order to obtain the best dynamic range in a _home theater._ Look at those graphs in Part 3 again. Consumer audio by its very nature has considerably less dynamic range than pro audio, because it's not required to deal with the crest factor of extremely high “live” signal levels. But just because the home theater signal chain does not utilize the full peak-signal capability of pro gear, that doesn’t mean we’re _limiting_ the pro gear's dynamic range. It only means we don’t _need_ all of it.




> For a clean reference signal (assuming a fully digital connection up to the AVR,) a -6dBFS peak sine should avoid all the Nyquist headache for a single channel test. You would just bump the master volume +6dB to compensate, as this is done after the digital section. For an LFE test you would want an identical -6dBFS wave on the LFE+L+R channels, and use bass management to send everything to the sub out. This will just fill the 5dB digital headroom in the DD processor, and allow a full strength signal out of the preout with the master volume at +6.
> 
> This is without getting into distortion levels. Such as, my AVR at 0mvl(corrected) will begin to audibly distort with a simple LFE channel signal of 0dBFS(corrected) without redirected bass with a channel level gain of +4dB of +12dB possible.


It sounds like you're talking about your specific equipment, which doesn't really help the rest of us. My AVR's master does not have any +dB settings, only -dB settings. If you're talking about the internal settings for the various channel's there's no universal standard as to what those figures actually reference. 




> This is without getting into distortion levels...
> 
> I also found that around +8dB I started to get premature clipping from my amp. Unfortunately, you can not register distortion/clipping with a DMM. It requires measurement.
> 
> The point of structured gain is to never get to the distortion/clipping level, but also maximize DNR of the total system. You can miss the distortion/clipping level, and still have lowered your DNR.


Any measurements would only be relevant for the particular equipment being measured - i.e. a specific system. That’s not particularly helpful to the big picture. 

And that’s probably why most gain structure articles don’t include measurements. They’re written to help the “man on site” perform the process without dragging along a portable laboratory of test equipment, so I don’t see why I should be held to a higher standard than paid professionals. Helping out fellow enthusiasts who aren’t especially technically-inclined, or who don’t have access to testing equipment, was the whole purpose of this piece. 

There is no reason to expect that distortion will be an issue after the gain structuring exercise. As I’ve noted, no one runs their system wide open in normal use. When the pre amp is turned down to its normal operating range, there will be ample headroom and dynamic range, and the signal will be as clean as the equipment in the system allows.

However, I plan to do some additional experimenting on pre-amp distortion and will modify the thread as needed.

As Leonard mentioned, the goal is to help out all the home theater folks who have been wandering in the wilderness and getting conflicting information on gain structuring from poorly-informed sources. We’re not trying to get laboratory perfection. But naturally it would be best for the advice and suggestions to err on the side of caution. 

*EDIT:*Additional testing confirmed that distortion from the pre amp outputs is a valid issue. Of primary concern, when the amplifier gains are set with using the maximum pre-amp output, the amplifier gains end up being set too low. This means the pre amp has to be turned up further to get the amps going, which most likely will lead to distortion from the pre amp during normal system operations. Appropriate additions have been made to Parts 7 and 9 taking distortion into account, and how to avoid it.


Regards,
Wayne


----------



## Man with a Flan (Feb 5, 2011)

*Re: Gain Structure for Home Theater: Getting the Most from Pro Audio Equipment in Your System*

Hi Wayne,

Let me first say thank you for your expansive treatment of this consumer/pro line interface issue. I have been trying to use my Crown K1 pro amp for two weeks now, and couldn't find much information into finding this article a few days ago. I really appreciate your enthusiasm and thorough explanations!

I have a 7.1 system with a Yamaha HTR-6160 AVR at the helm. It is rated at 110 watts/channel with all 7 channels running, although I don't believe that. I recently upgraded my fronts to Polk RTA 15tl's (91db 8 ohm 250 watt rms, four 6.5" drivers) and decided it was a great opportunity to outsource their amplification to a 350 watt/channelCrown K1 I had sitting around. I wanted more heft behind the speakers, and also wanted to ease the burden on my AVR. Initially I simply used an rca-to-1/4" cable from my pre-outs to the Crown, but I couldn't get the same volume that I got from the Yamaha. Today I realized that the 1/4" plug was not a balanced TRS but the other kind (TR?) So perhaps I should get another cord? I didn't realize this though until today. FYI The Crown has an input sensitivity of 1.4 vrms and the Yammie (according to the manual) passes a 1 volt signal from the pre-outs.

I ended up getting a Samson S-Convert, ran XLRs into the Crown, and it was much, much better. The bass was awakened compared to when the Yamaha drove them. I did some guessing here and there, though, since now I had three knobs to affect volume (gain knobs on the Crown, gain knob on the S-Convert, and of course the AVR's control. My Yamaha's volume spread is -80 -- +16.5. When I calibrated my speakers for 7.1 a while back with an SPL, I used 75db as my reference. I rarely go past -18 on the Yamaha, and my front speaker levels are set at 4.5 on a scale 1 -10. I like not maxing out my system in any setting, so I left everything alone when testing out the S-Convert. Just going by my ears, I noticed a lot more hiss during the music's quiet passages when I maxed out the sensitivity gain on the amp. And when instead I maxed out the S-Convert's gain and moved the Crown's knob back to its middle setting I could hardly hear any noise. The AVR was also playing a lot louder than normal at -11. I was pretty impressed with the results, but still felt there were other ways to measure than my ears and my gut. The next day I found your article. 

I decided to do the voltage test on my Yamaha pre-outs. I got a digital multi-reader and downloaded your sine waves and pink noise.

I unplugged all my speakers and raised the L and R speaker evels on the AVR to max. I connected a DVD player with a digital coax connection and bipassed all tone and signal processing with the "pure direct" feature. I played the 60hz sine wave track. I turned up my Yamaha and got to about -7, then it promptly shut off. The voltage reading was always about 2-2.4 volts when this happened. 

First off, should I be concerned about damaging the receiver? Why is it going into protection mode? Considering max volume is +16.5, I'm surprised that -7 volume is overloading it. I understand that I've also maxed out my L and R levels from 4.5 to 10, so that contributes. But I was really not expecting this shut down to happen. This receiver has given me no trouble before.

Next thing I did was reconnect the pre-outs to the S-Convert and take a voltage reading from the balanced XLR cable that's headed to the Crown. The S-Convert was at it's middle setting on its gain knob, which the manufacturer refers to as its "unity gain". This time I got to -12 on the Yamaha, also just over 2 volts on the multimeter, before the receiver turned itself off.

The next step was running the 1 khz sine wave through a speaker. I had to go through the S-Convert but left it at unity gain, and the Crown's sensitivity gain was just at the 2nd notch, the first notch that made the sine wave audible. I got to -34 on the AVR and just quit. It was loud enough to hurt my ears, but no harmonic overtone. I guess that wave is so pure it just sounded extra loud. 

*So I'm kind of at a stand still because:

1)* After my amp shutting down so much I'm concerned about busting speakers when the 1 khz distorts through my tweeters.

*2* I don't understand why my voltage test shut the AVR down. BTW Just out of curiosity I tested the voltage on the back of the DVD player, also with the 60 hrz track. Both with the analog rca and the coax digital outs the signal was 4v, and in fact even more because it was going immediately to error on the multimeter since I was measuring in the 4v range. I just checked the Yamaha manual and noticed a "maximum input voltage (effect on, 1khz, 0.5% THD)" = 2.3v. I know I was testing with 60hz, but is it possible the Yamaha shut down because of it's input limit, not output limit? Does its volume knob simply control its own input sensitivity just like the knobs on the S-Convert and the Crown K1? 

*3)* I'm also wondering if I should return my L and R speaker levels to it's SPL calibrated levels on my Yamaha, put the volume to -20 (a median movie watching level for me) and see what voltage it's delivering to the S-convert, and concurrently the amp.

*4)* Maybe I simply need to get a rca-to-TRS interconnect? It will balance the signal? But not boost it?

*5)*There also is another piece of hardware called the Ebtech Line Level Shifter. It does the same as the S-Convert except it's passive circuitry, and requires no power. So theoretically it is sonically transparent and conveys no noise floor of its own?

The S-Convert has a s/n ratio of 90 db
Yamaha: "s/n ratio (IHF -A Network) CD, etc (effect off, 250mv) --100db or more
Crown has >100

I hate to overthink all this considering it sounded good, but in respect to all the data you provided, I'd really rather know the signal chain is running clean and trouble-free.

Sorry for trying to write more words than your article had! This is my first post, but I plan on easier topics after this! Like, "Name your favorite subwoofer movie?"

Thanks!


----------



## Man with a Flan (Feb 5, 2011)

Bump?


----------



## soho54 (Jul 22, 2006)

*Re: Gain Structure for Home Theater: Getting the Most from Pro Audio Equipment in Your System*

I thought I had posted to this awhile ago, but I guess not? :scratch:



lcaillo said:


> Your posts are very helpful, so don't consider my comments to be purely critical. I simply want to make it more likely that the general reader gets the point.


 I didn't find any problems with them. You are absolutely correct about the 1bit in analog comparison. I use it help help explain the difference, as I find more people _get_ the idea better that way, but normally I add a line about it not being technically correct.

I tend to write my posts as a stream of consciousness off the top of my head, in a spare minute or two here and there, and sometimes things get left out. I screw up too, and have no problem with someone pointing it out. 



Wayne A. Pflughaupt said:


> Basically you're re-stating the max-levels theory. However, pro gear, just like consumer, can be operated at any signal level, and a high or low level does not change the noise floor of the component in question. The component’s noise floor is fixed. It’s _not_ going to increase, even if you reduce the signal down to the level of background music, or even to zero.


I'm not talking about max-levels theory here, but it is similar. I was talking about a digital processor there, but lets touch the analog first.

You are correct the noise floor of each individual component does not change. The input to output ratio (or gain) does though. The idea is to have the input as high as possible to get a good SNR through the component. If the signal input is too low you lower this ratio on the output, and you can't get it back. This is the cause of the dreaded hiss. The idea is to have enough signal to avoid this noise creep. 

Max-Levelers take this to the extreme, and hook everything up to an oscilloscope, and wring every last bit out of a piece of gear. As a result the manufactures keep adding more headroom, to appeal to these guys. This is fine, but once you signal is high enough to avoid audible hiss it isn't worth much to anyone else.




Wayne A. Pflughaupt said:


> *EDIT:*Additional testing confirmed that distortion from the pre amp outputs is a valid issue. Of primary concern, when the amplifier gains are set with using the maximum pre-amp output, the amplifier gains end up being set too low. This means the pre amp has to be turned up further to get the amps going, which most likely will lead to distortion from the pre amp during normal system operations. Appropriate additions have been made to Parts 7 and 9 taking distortion into account, and how to avoid it.


This is a very good step in the right direction. I would also suggest doing the same thing to the sub channel. Depending on the AVR, things can be a bit different between the LFE out, and the other channels.

I shout out to REW would be nice as well, as it can run the test on all your components individually in loopback mode should one get the itch.



Wayne A. Pflughaupt said:


> It will work just fine with a consumer signal level with no noise penalty. Any background noise it may have is fixed and will not change with signal levels, so choose your accessories carefully.


 This is worded a little oddly. The component noise floor is static, but the component SNR and the total system noise floor is not. If you have a low signal voltage going into a digital processor (anything really) the SNR will be lower when it hits the output stage, than a larger input signal. As a result in the next component in the chain will receive a signal with a lower SNR, and in the end usable DNR. 

Lets say you are using a signal with an average level of -20dB. You run it through a component using a low voltage level, and your -20dB is now only 30dB above the noise floor. When you amplify the signal in the next component your -20dB signal is at say 80dB SPL, and the hiss from the processor is now amplified to 50dB SPL.

If you go back and raise the input voltage level 10dB, your -20dB average signal is now leaving the the component at 40dB above the noise floor. When amplified you end up with the same 80dB SPL average level with a 40dB SPL noise floor. This is why you start from the beginning, and work down the chain. You can't make things any better down the chain, only hold it steady, or make it worse. 

You don't need to have everything at the input limits, but you do want them to be high enough to keep the noise floor from creeping up on you. This point will be different for every setup, as every piece of gear (including the speakers,) will have a different effect on the overall system response.


----------



## soho54 (Jul 22, 2006)

*Re: Gain Structure for Home Theater: Getting the Most from Pro Audio Equipment in Your System*



Man with a Flan said:


> I unplugged all my speakers and raised the L and R speaker evels on the AVR to max. I connected a DVD player with a digital coax connection and bipassed all tone and signal processing with the "pure direct" feature. I played the 60hz sine wave track. I turned up my Yamaha and got to about -7, then it promptly shut off. The voltage reading was always about 2-2.4 volts when this happened.
> 
> First off, should I be concerned about damaging the receiver? Why is it going into protection mode? Considering max volume is +16.5, I'm surprised that -7 volume is overloading it. I understand that I've also maxed out my L and R levels from 4.5 to 10, so that contributes. But I was really not expecting this shut down to happen. This receiver has given me no trouble before.


 This is normal. It is a little low for it to be happening though. You have the AVR trying to put out too much voltage. I would suggest resetting all the channel levels in the AVR to 0, then recalibrate manually with an SPL meter adjusting the amps themselves instead of the AVR. You should be able to run at ~ +4dB with a 0dbFS sinewave for ~2minutes before the cut out. Then once working again, you can try to tweak things out if you want.

As for the numbered section:
1) I wouldn't push my luck.

2) You had the AVR trying to put out more juice that it could handle. See above.

3) Do not try to run sinewaves with the channel levels at max with a high MV on a Yami. It will just shut itself off. _This is not a knock against Yami, as *I run one myself*, but it is an issue you will find with extreme level sinewave testing._

4) Just turn the AVR channel levels back down, and then go from there.

5) I don't think you need to buy anything else. You just need a good tweak on what you have.


----------



## Wayne A. Pflughaupt (Apr 13, 2006)

*Re: Gain Structure for Home Theater: Getting the Most from Pro Audio Equipment in Your System*




Man with a Flan said:


> I rarely go past -18 on the Yamaha, and my front speaker levels are set at 4.5 on a scale 1 -10.


 That may be part of the problem. I’d suggest setting the front L/R speakers as high as you can in the menu. Naturally, the rest of the speaker levels have to be considered, but I’d raise _all_ the speaker levels as high as possible. For instance, whichever speaker you have set highest now – say, you have the mains set for 4.5 and rears set for 7. Assuming all the speaker adjustments have the same 1-10 scale you mentioned, I’d raise the rears +3 dB to get them up to 10, and all the other speakers +3 dB as well (i.e. 4.5 becomes 7.5). Make sense? Don’t worry about “maxing out any setting.” It’s a “chicken and eggs” thing: Lower per-channel settings in the menu will mean a higher master volume setting is required in regular use, while the reverse is true for higher per-channel menu settings. In the end, what the main volume control delivers is what matters.





> know I was testing with 60hz, but is it possible the Yamaha shut down because of it's input limit, not output limit? Does its volume knob simply control its own input sensitivity just like the knobs on the S-Convert and the Crown K1?


Not likely. Typically input sensitivity controls, if they exist, are a separate adjustment. For instance, the old Yamaha DSP-A2070 5.1 integrated amp I used back in the Dolby Pro-Logic days had a menu function that could trim adjustment for each input ± 6 dB.




> First off, should I be concerned about damaging the receiver? Why is it going into protection mode? Considering max volume is +16.5, I'm surprised that -7 volume is overloading it. I understand that I've also maxed out my L and R levels from 4.5 to 10, so that contributes.


No, you aren’t going to damage anything – the protection mode will prevent that.

That said, I’m unsure why that’s happening. I can’t imagine how or why a receiver would go into “protect” with no speakers connected, but gear these days is a lot different (“smarter”) than it used to be. Who knows, it may be sensing a strong, relatively steady-state signal as something that would be potentially damaging to speakers (which it is!), and mandated by the legal department as something that needs to be prevented. 

It may be that a dummy load is needed to “pacify” the amplifier section. Typically this is something like an 8-ohm, 100-watt resistor.




> The S-Convert has a s/n ratio of 90 db
> Yamaha: "s/n ratio (IHF -A Network) CD, etc (effect off, 250mv) --100db or more
> Crown has >100


The Crown’s noise spec is also A-weighted, which is a disappointment. Still, in the end all that matters if noise is at what you’d consider an acceptable level.




> 4) Maybe I simply need to get a rca-to-TRS interconnect? It will balance the signal? But not boost it?


No, it takes a passive transformer or active circuit to convert unbalanced to balanced. It can’t be done with a cable.




> The next step was running the 1 khz sine wave through a speaker. I had to go through the S-Convert but left it at unity gain, and the Crown's sensitivity gain was just at the 2nd notch, the first notch that made the sine wave audible. I got to -34 on the AVR and just quit. It was loud enough to hurt my ears, but no harmonic overtone.


I assume you were trying to do the “clean voltage” test. The S-convert could be used to reduce the signal to the amplifier further (beyond what you can get with just the amp’s gain controls), so that the speakers wouldn’t be playing so loud. This will have no effect on the “clean output” measurement you’re after.

The maximum- and clean-voltage tests are mainly “FYI” exercises. It’s useful information to have before you go shopping for an amp, to make sure you don’t waste your money on one your receiver can’t drive. Since you already had your amp, you can just cut to the gain-matching exercise described in Part 8, using the pink noise and SPL meter - i.e. comparing one channel that’s receiver -> speaker to the other channel that’s receiver -> amplifier -> speaker. If you can get a gain match, you’re good to go (don’t forget to first push your per-channel settings in the menu as high as possible). If not, and the differential with the receiver -> amplifier -> speaker is unacceptably low, then use your S-convert at its lowest gain setting that will achieve the gain match.

Let us know how things go. :T

Regards,
Wayne


----------



## Wayne A. Pflughaupt (Apr 13, 2006)

*Re: Gain Structure for Home Theater: Getting the Most from Pro Audio Equipment in Your System*




soho54 said:


> You are correct the noise floor of each individual component does not change. The input to output ratio (or gain) does though. The idea is to have the input as high as possible to get a good SNR through the component.


You are confusing SNR (signal to noise ratio) with dynamic range.




soho54 said:


> If the signal input is too low you lower this ratio on the output, and you can't get it back. This is the cause of the dreaded hiss. The idea is to have enough signal to avoid this noise creep.


Nope. The cause of the hiss is components in the signal chain with high background noise levels - IOW, poor SNR.




soho54 said:


> This is worded a little oddly. The component noise floor is static, but the component SNR and the total system noise floor is not.
> <snip>
> If you go back and raise the input voltage level 10dB, your -20dB average signal is now leaving the the component at 40dB above the noise floor. When amplified you end up with the same 80dB SPL average level with a 40dB SPL noise floor. This is why you start from the beginning, and work down the chain.


 How do you propose we raise the input voltage? This is home audio, not pro audio. We don’t have the pro audio luxury of input gain controls to improve the S/N of the signal source. Instead, our front-end signal levels are fixed by the source components and AVR. The only way to increase the signal level post-AVR is to use an external device, which will also boost any background noise from the AVR by whatever amount you boost the signal. Kinda nukes the increased S/N we’re after right out of the hole. 




> Lets say you are using a signal with an average level of -20dB. You run it through a component using a low voltage level, and your -20dB is now only 30dB above the noise floor. When you amplify the signal in the next component your -20dB signal is at say 80dB SPL, and the hiss from the processor is now amplified to 50dB SPL.


 Exactly how and why is the signal automatically “amplified” as it passes from one component to the next? It won’t be _automatically_ amplified, and it most certainly should not be manually amplified. That would be contrary to standard gain structure protocol. According to most professional references, post-pre amp signal boosting is not recommended because it will increase the noise floor from the source component and pre amp. This is supported by the Rane article referred to in Part 2 (among other sources), which notes that the only gain changes that should be effected in downstream processors is to counter what might come from the processor itself – like an overall change in signal strength from an equalizer, for instance. The signal is not – and indeed should not – be “amplified” from one component to the next. I think you’d be hard pressed to come up with any professional references that say otherwise.

This was all discussed - and adequately discounted - throughout the article. The meters on my pro-audio Yamaha EQs rarely get above -30 to -24 (i.e. < half-scale) and indeed most of the time they’re barely getting off the bottom. Yet my system is dead silent. :whistling:

Quiet (read quality) equipment is what determines system noise, not signal levels. Every gain structure-related thread I’ve ever seen that dealt with a noise issue, the problem was ultimately isolated to a certain piece of equipment (a classic example can be seen in the link to an AVS thread found in Part 4). I’ve yet to see a thread where a noise issue was determined to be caused by inappropriate signal levels.

You’ve spent two pages now rehashing the same arguments, but have yet to offer a better solution or procedure for doing this. :huh:

Regards,
Wayne


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## soho54 (Jul 22, 2006)

*Re: Gain Structure for Home Theater: Getting the Most from Pro Audio Equipment in Your System*

Nah, you seem to be mixing what I said in with the digital signal limit issue you seem have a bone about, and that is not what I was talking about. The input meter readout level is irrelevant here.

What I posted is fact, and can be easily demonstrated. The input and out put levels at every stop along the chain will effect the total/final/in room system noise floor. I also stated throughout these posts that each system is different, and each stop along the chain will alter things one way or the other. Inefficient speakers, and/or a noisy room will hide a lot of problems.  This is what some are finding out now when switching from small inefficient 87dB mains to 100dB+ mains.

You haven't discounted anything in the article, you just say a lot of things don't exist, or will never be a problem, that anyone with a little experience with a lot of different gear knows to be real issues. That is what prompted my posting here in the first place. 

I fail to see how you being able to set your system up a certain way somehow voids anything I have said, or proves your views right in all (or even most) situations. I have a mixed pro/home setup that is dead silent with my main set of speakers, but I demo a lot of gear, and know that it is not dead silent with other speakers hooked up. It takes different amps, processors, and a completely different gain setup to get close to dead silent with say the DSL SH60s in my room.

I going to give up now.


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## dsime42 (Mar 4, 2011)

*Re: Gain Structure for Home Theater: Getting the Most from Pro Audio Equipment in Your System*



Wayne A. Pflughaupt said:


> That would be contrary to standard gain structure protocol. According to most professional references, post-pre amp signal boosting is not recommended because it will increase the noise floor from the source component and pre amp. This is supported by the Rane article referred to in Part 2 (among other sources), which notes that the only gain changes that should be effected in downstream processors is to counter what might come from the processor itself – like an overall change in signal strength from an equalizer, for instance. The signal is not – and indeed should not – be “amplified” from one component to the next. I think you’d be hard pressed to come up with any professional references that say otherwise.
> 
> ...
> 
> Quiet (read quality) equipment is what determines system noise, not signal levels. Every gain structure-related thread I’ve ever seen that dealt with a noise issue, the problem was ultimately isolated to a certain piece of equipment (a classic example can be seen in the link to an AVS thread found in Part 4). I’ve yet to see a thread where a noise issue was determined to be caused by inappropriate signal levels.



Hi
I'm just a little confused here.
The "post-pre amp signal boosting is not recommended" statement seems diametrically opposed to your Figure 2 where 3dB is added between the Notch Filter and again before the Limiter, but I don't see anything on that graphic labeled "preamp" hence my confusion.

Also
When I look at Figure 1 I see a System Dynamic Range (SDR) of 72dB and the Figure 2, after alignment, shows an SDR of 90 dB. Then in the rest of the article you make the case that the original 72dB was enough and in fact loss of an additional 6 or 12 dB would not be an issue. Sorry I think I missed something.


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## Wayne A. Pflughaupt (Apr 13, 2006)

*Re: Gain Structure for Home Theater: Getting the Most from Pro Audio Equipment in Your System*




soho54 said:


> What I posted is fact, and can be easily demonstrated. The input and output levels at every stop along the chain will effect the total/final/in room system noise floor.


This problem could easily be avoided by making sure the input and output levels are the same for each processor in the signal chain – as they should be. Standard pro-audio gain structure protocol, that in this case works for home theater too.




soho54 said:


> I have a mixed pro/home setup that is dead silent with my main set of speakers, but I demo a lot of gear, and know that it is not dead silent with other speakers hooked up. It takes different amps, processors, and a completely different gain setup to get close to dead silent with say the DSL SH60s in my room.


If your system is dead silent and you get noise after changing out a piece of equipment, it should be obvious that it is an inferior piece of gear.




soho54 said:


> I going to give up now.


 We are still waiting for your recommendation for a better method for “regular Joes” who don't have any professional calibration equipment.




dsime42 said:


> I'm just a little confused here.
> The "post-pre amp signal boosting is not recommended" statement seems diametrically opposed to your Figure 2 where 3dB is added between the Notch Filter and again before the Limiter...


Yes, they do seem contradictory. The graph came from a different reference source than the Rane article. As I noted in Part 1 a few paragraphs above the graphs, it’s not uncommon for different gain structure references to have a certain amount of inconsistencies from one to the next. For a mixed home/pro system, the Rane information is what's relevant, because we don’t use outboard components like notch filters and limiters that have their own gain-boosting capabilities (the exception being sophisticated systems that use electronic crossovers or digital speaker processors).




> ...but I don't see anything on that graphic labeled "preamp" hence my confusion.


Keep in mind that the graphs depict a professional PA system. In a PA system, the mixing console has essentially the same function as a home audio pre amp – i.e. it’s the piece that all the input sources plug into.




> When I look at Figure 1 I see a System Dynamic Range (SDR) of 72dB and the Figure 2, after alignment, shows an SDR of 90 dB. Then in the rest of the article you make the case that the original 72dB was enough and in fact loss of an additional 6 or 12 dB would not be an issue. Sorry I think I missed something.


Sorry but I have no idea how you arrived at the conclusion that I said the original 72 dB SDR was adequate. The primary purpose for those two graphs was to show that a proper gain structure would improve system dynamic range. The equipment depicted in the graphs is pro gear from top to bottom, and as such isn’t specifically relevant to a mixed home/pro system. The only reference I made to a “loss” of signal not mattering was specifically referring to any 24-bit digital processors used in a home system downstream from the pre amp.

Regards,
Wayne


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## jianhua1975 (Sep 13, 2011)

*Re: Gain Structure for Home Theater: Getting the Most from Pro Audio Equipment in Your System*

Hi, Wayne:
just some junior questions:
i am using pure Pre amp(7.1) + poweramp(5 channel) + powered Sub.
and i'd like to know what you are refering to for "Gain control", " volume control" and "speaker level setting" in pure preamp? i only know that Volume control shall be the volume Knob in Preamp's front panel. 
what about other two, shall be in the menu right??

and for Preamp setting as analog input with Bypass(is that what you mentioned as setting to "bypass" , "Stereo","direct"? ), which means there is no Dsp working for bass management at all. so Subout will be no signal, and Xover point setting will be bypassed also, in this case how to measure sub?


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## Wayne A. Pflughaupt (Apr 13, 2006)

*Re: Gain Structure for Home Theater: Getting the Most from Pro Audio Equipment in Your System*




> i am using pure Pre amp(7.1) + poweramp(5 channel) + powered Sub.
> and i'd like to know what you are refering to for "Gain control", " volume control" and "speaker level setting" in pure preamp? i only know that Volume control shall be the volume Knob in Preamp's front panel.
> 
> what about other two, shall be in the menu right??


Yes, with an AV pre-amp, speaker-level settings are typically in the menu. Gain controls for the various input sources are kind of rare, but they would be in the menu, too.



> and for Preamp setting as analog input with Bypass(is that what you mentioned as setting to "bypass" , "Stereo","direct"? ), which means there is no Dsp working for bass management at all. so Subout will be no signal, and Xover point setting will be bypassed also, in this case how to measure sub?


Many AV receivers (or pre amps) keep the subwoofer output active when you set it for “Bypass” or “Stereo Direct.” If yours isn’t like that, just go ahead and use whatever setting is needed to activate the subwoofer output, so you can take your voltage measurements. :T

Regards,
Wayne


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## rob92266 (Dec 16, 2011)

*Re: Gain Structure for Home Theater: Getting the Most from Pro Audio Equipment in Your System*

i just cant figure it out, so this is what i am running for gear first of all:

marantz sr7000 avr
2 - dual 15" jbl bins with jbl horns for the fronts
1 - center channel speaker
1 - 15" peavy sub
2 - b & w speakers for the surrounds
1 - behringer mx882 line level matching/splitter/mixer
1 - behringer epq1200 for the surrounds
1 - behringer epq1200 for the center and for the sub
1 - behringer epq2000 for the fronts

total power is 4400 watt

this is how i have it hooked up, i hope this is right.

from the avr preouts, fronts, center, sub and surrounds connect to the inputs on individual channels ( 1 through 6 )on the mx882 with rca to xlr, then from the mx882 outputs for each channel (using xlr cables )go to the dedicated amps, and the speakers are connected from the amps, it just seems to me that since i am running 4400 watts that it should be much louder, the amps are maxed out and the volume control on the avr has a range from -60 to +15, so when i am watching tv the volume is set at around -24, so i dont know if this is correct or someone can help me out here, and help would be appreciated


----------



## Wayne A. Pflughaupt (Apr 13, 2006)

*Re: Gain Structure for Home Theater: Getting the Most from Pro Audio Equipment in Your System*


See this cross-posted thread.

Regards,
Wayne


----------



## sportflyer (May 2, 2010)

*Re: Gain Structure for Home Theater: Getting the Most from Pro Audio Equipment in Your System*

Wayne, 

I am thinking of using a Pro Crossover for example a DBX 223( or similar unit from Behringer, ART etc) as a crossover for bass management between a tube preamp and SS power amp. to integrate a SVS subwoofer Now that I read your articles above I am wondering whether this is a suitable application of the DBX 223 as a bass management unit in a home Stereo environment. BTW I am already using a BFD for Sub EQ 

I have questions re the gain settings of this unit. Does 0db in the gain dials mean unity gain ? 

Maybe its better to find a used XO unit designed specifically for home audio like the Paradigm X-30 , Energy EAC etc. ? Bryston XO unit is too costly for me. 

Advice?


----------



## Wayne A. Pflughaupt (Apr 13, 2006)

*Re: Gain Structure for Home Theater: Getting the Most from Pro Audio Equipment in Your System*


Yes, a 0 dB setting on the input and output knobs is unity gain.

There’s no reason a pro crossover won’t work, from a functional standpoint. However, with any budget pro audio gear there is a concern that it might not be as quiet or as clean as good home equipment. I’d suggest subjecting it to the battery of tests I outlined in Part 8 to make that determination.

Naturally, this is only a concern if you intend to use both the high and low pass outputs from the crossover. If you’re only using the low pass (for the subs), then noise is not an issue.

Regards, 
Wayne


----------



## sportflyer (May 2, 2010)

*Re: Gain Structure for Home Theater: Getting the Most from Pro Audio Equipment in Your System*



Wayne A. Pflughaupt said:


> Yes, a 0 dB setting on the input and output knobs is unity gain.
> 
> There’s no reason a pro crossover won’t work, from a functional standpoint. However, with any budget pro audio gear there is a concern that it might not be as quiet or as clean as good home equipment. I’d suggest subjecting it to the battery of tests I outlined in Part 8 to make that determination.
> 
> ...



I was planning to use it for LP and HP. So I think I might be better off buying a used XO specifically designed for home stereo. Used equip from Paradigm, Mirage, Energy and Outlaw are about the same price as new Pro XO from Behringer, DBXpro , Rane etc . This way I dont have to worry about noise floor and dynamic range . Looks like I will be patiently scouring the ads  

Tks


----------



## apilon (May 18, 2006)

*Re: Gain Structure for Home Theater: Getting the Most from Pro Audio Equipment in Your System*

Wayne 

very informative articles. My question is i drive a DIY sub with a Behringer EP-4000 which is connected to an Onkyo TX-NR818 

Everyone is telling me to set the ep4000 gain to max and use the sub trim to bring it down to 75 DB but even with the trim max out at -15 db the spl is registering over 80 db 

How can i use your article to properly do a gain structure on my sub??

Alain


----------



## Wayne A. Pflughaupt (Apr 13, 2006)

*Re: Gain Structure for Home Theater: Getting the Most from Pro Audio Equipment in Your System*


Hey Alain,

Typically the amp would only need to have its gains run wide open if it was getting a weak input signal. However, from what I’ve picked up on various forums, Onkyo receivers have unusually high voltage levels from their RCA outputs. So starting with the amp’s gains maxed out is a bad idea in your case. Your best bet would be to ignore what “everyone” is telling you and follow the simple steps laid out in Part 9 of the article. :T

Regards, 
Wayne


----------



## apilon (May 18, 2006)

*Re: Gain Structure for Home Theater: Getting the Most from Pro Audio Equipment in Your System*



Wayne A. Pflughaupt said:


> Hey Alain,
> 
> Typically the amp would only need to have its gains run wide open if it was getting a weak input signal. However, from what I’ve picked up on various forums, Onkyo receivers have unusually high voltage levels from their RCA outputs. So starting with the amp’s gains maxed out is a bad idea in your case. Your best bet would be to ignore what “everyone” is telling you and follow the simple steps laid out in Part 9 of the article. :T
> 
> ...


Thanks Wayne 

I believe i will need to perform step 7 before to get the sub maximum usable clean output ?? If so do i need to measure the mains also as stated or can i just measure the sub output?

Finally just to make sure i understand correctly, step 3 adjust the level of all channels utilizing outboard amplifiers to their max settings . Are you refering to the AVR trim level that i should max out to +15DB ??


----------



## Wayne A. Pflughaupt (Apr 13, 2006)

*Re: Gain Structure for Home Theater: Getting the Most from Pro Audio Equipment in Your System*


Part 7 is mainly to help people determine if their receiver generates enough clean voltage to drive a pro amp. We already know that yours can, so you can skip that part. Just set your AVR’s sub output for 0 dB and adjusted the amp’s gains as needed, per Part 9.

Regards, 
Wayne


----------



## dsime42 (Mar 4, 2011)

*Re: Gain Structure for Home Theater: Getting the Most from Pro Audio Equipment in Your System*

Hi Wayne
I look forward to reading the rest of this article but I started on #5 (Myths) and am having a problem with a couple of your statements.

RE: "A 24-bit system in particular can shed several hundred thousand LSBs from its 16,777,216 quantization steps"
While it may be true that a 24-bit system could "shed several hundred thousand *STEP*s from its 16,777,216 quantization steps" it cannot shed more *BIT*s than it has. Hence a 24 bit system will have One (1) MSB and 23 bits that are less significant and could possibly be called LSBs though once you get past halfway (12 bits) it starts to become semantics.

Any way you slice it you can not shed more bits than exist. ie 24


RE: The chart you show with the three bit system.
You have a left axis labelled "000 001 010 011 100 101 110 111" and you illustrate the loss of a *BIT* as being synonymous with the loss of the "000" state. This is incorrect
Loss of a bit isn't "really loss of the bit it is loss of the "usefulness" of the bit and the LSB is also NOT the lowest state representable by the system as you have shown.
A more correct chart would have had its left axis labelled "00x 00x 01x 01x 10x 10x 11x 11x". Note that ALL of the LSBs on the axis have been changed to 'x' representing the fact that while they still exist they cannot be relied on to provide [good] data. 

In addition the sharp red line showing the steps should be changed to reflect this "uncertainty" by becoming a pinkish-grey area encompassing that part of the graph where the LSB could be either a '1' or a '0' .

Following the top edge of this grey area would show that now you actually have a TWO (2) bit system with another bit worth of grey area below it. The "uncertain area", where "valid data" does not exist is commonly referred to as noise.


An interesting extension of this chart would be to "lose" two (2) LSBs.
With the chart as you depict it only "two states" would be lost but with the axis label correctly it would depict a one (1) bit system with a considerable pink-grey area.

Of course the logical conclusion to this would be a 3-bit system with the loss of ... ... wait for it  ... the three (3) LSBs the label would be an uninteresting list of 'xxx' and the entire chart would be pink-grey and it would be easy to see that the chart is nothing but noise.


----------



## apilon (May 18, 2006)

*Re: Gain Structure for Home Theater: Getting the Most from Pro Audio Equipment in Your System*



Wayne A. Pflughaupt said:


> Part 7 is mainly to help people determine if their receiver generates enough clean voltage to drive a pro amp. We already know that yours can, so you can skip that part. Just set your AVR’s sub output for 0 dB and adjusted the amp’s gains as needed, per Part 9.
> 
> Regards,
> Wayne



Got it Thanks 

2 more questions and i am on my way......

1. Do i leave the clip limiter on or off for that test on the ep4000?

2. as for the avr volume to i set it to max or 0db reference level?


----------



## Wayne A. Pflughaupt (Apr 13, 2006)

*Re: Gain Structure for Home Theater: Getting the Most from Pro Audio Equipment in Your System*




dsime42 said:


> Hi Wayne
> I look forward to reading the rest of this article but I started on #5 (Myths) and am having a problem with a couple of your statements.


Thanks for clarifying, desime. :T The 3-bit graph came from Wikipedia (http://en.wikipedia.org/wiki/A/D_converter). Not being well versed in the finer points of A/D conversion, when they showed a quantization step as a LSB(it) I presumed that “bit” and “step” were the same thing. 

The point of the discussion was to show that despite the fables that have circulated the home audio forums for nearly 15 years, 24-bit processors are essentially immune to poor input signal levels – you didn’t shoot that part down, so hopefully I’m okay there! 

Regards, 
Wayne


----------



## Wayne A. Pflughaupt (Apr 13, 2006)

*Re: Gain Structure for Home Theater: Getting the Most from Pro Audio Equipment in Your System*




apilon said:


> 2 more questions and i am on my way......
> 
> 1. Do i leave the clip limiter on or off for that test on the ep4000?


I’d leave it off for the gain setting process. The whole purpose of the gain structure exercise is to make sure the amp clips at the same time as the pre-amp. So, once that’s done, the limiters merely add an extra layer of protection. 

That said, I think most people would agree that 30 Hz is way too high a high pass filter for a home theater subwoofer. That essentially reduces the extension of a beefy DIY sub to par with the typical 10-inch manufactured sub.



> 2. as for the avr volume to i set it to max or 0db reference level?


With your receiver, which has perhaps 2-3 times the output of most others, I don’t think you have to be overly concerned by all this. You can just adjust the amp’s gains for subwoofer level setting the same way that you would for a common powered sub.

Regards, 
Wayne


----------



## apilon (May 18, 2006)

*Re: Gain Structure for Home Theater: Getting the Most from Pro Audio Equipment in Your System*

Good evening Wayne 

I performed the steps in part 7 sub trim 0db played the sin wave but bottom line i had to max out the Onkyo volume to +18db in order to get the Behringer ep4000 to clip and got a steady clip light at +25db on the ep 

Thanks for your help 

Alain


----------



## tomstrade (Mar 13, 2014)

*Re: Gain Structure for Home Theater: Getting the Most from Pro Audio Equipment in Your System*

Wayne, thanks for this great thread on gain setting. I guess I'm a little late to the party.  

I have a Denon 4520 that I'm trying to match up with a Crown XLS2500. Running through your steps I am a bit stuck determining the 4520 preout harmonic distortion threshold. I downloaded your test tones to a USB stick and are running the tones off the USB stick and 4520's MP3 decoder. Using the 1kHz sine signal I can easily detect harmonic distortion once I hit 78 on the Denon volume control (whereby the range is set for 0-98). The problem I have is that I hear this distortion at 78 no matter how high or low the speaker levels are set for - on the 4520, that would be -12 to +12dB. Is this typical? Wouldn't I expect to at least "move" the harmonic distortion point along the volume continuum as I change the speaker levels? Any reason why I can only hear it at volume level 78?


----------



## Wayne A. Pflughaupt (Apr 13, 2006)

*Re: Gain Structure for Home Theater: Getting the Most from Pro Audio Equipment in Your System*


Hey Tom,

So you’re saying that you run the Denon’s master volume up to 78, and at that point you can hear the distortion begin. And from there if you adjust the per-channel level from the menu _for the speaker you’re hearing,_ that there is no change? IOW, you can reduce the volume of the speaker that way and still hear distortion?

If that’s the case, yes I would think that’s unusual, but then again there are just too many receivers on the market for me to know if this is typical or not, and digital processing can be tricky.

Regards, 
Wayne


----------



## tomstrade (Mar 13, 2014)

*Re: Gain Structure for Home Theater: Getting the Most from Pro Audio Equipment in Your System*

Thanks Wayne. Yes, when I change the speaker "trims" I would expect the voltage output to change, but it does not. One theory a friend (that is an engineer) told me is that perhaps it needs to be loaded - so maybe a Y cable with one into the Crown (volume turned down) and measure off the Y. While I'd like to figure this out, I've moved on to other gear so it's a bit moot. I appreciate your response though. Thanks.


----------



## corradizo (Jan 19, 2014)

*Re: Gain Structure for Home Theater: Getting the Most from Pro Audio Equipment in Your System*

Does dialing in your speakers to 75db with pink noise make 0db on your receiver represent 75db at mlp? Then setting the sub gain to zero on the receiver and using the gain to get it up to 75db (with eq running and receiver on) makes it match your mains? As long as you don't clip it doing this aren't you safe? Ie using pink noise from your receiver.

Pete


----------



## Wayne A. Pflughaupt (Apr 13, 2006)

*Re: Gain Structure for Home Theater: Getting the Most from Pro Audio Equipment in Your System*


Hi Pete,

The article is about proper gain setting in a system using outboard pro audio gear. It’s not about adjusting speaker levels with a standard AVR and powered subwoofer. I suggest opening a thread with your question in one of the main forums.

Regards,
Wayne


----------



## DevonD (Apr 27, 2009)

*Re: Gain Structure for Home Theater: Getting the Most from Pro Audio Equipment in Your System*

Hi Wayne,

I have read many of your articles on REW and just recently started playing around with implementing a hard knee house curve as a result of your suggestions on the topic. Thank you for another great article!

I am using my AVR to power my speakers but am using a pro amp on my subwoofer. My setup is as follows;
-Denon 4311ci AVR: spec'd at 1.2Vrms output (I have not measured)
-MiniDSP balanced with selectable .7V or 2V input sensitivity and 2Vrms output
-Peavey Ipr2 5000 amplifier on my subwoofers- 1.95V input sensitivity. 

The Peavey owner’s manual recommends keeping the gain dial turned all the way clockwise for “maximum headroom” and this is how I have always ran it. I have noticed that at lower volumes the subwoofer doesn’t seem to do much, I have felt the volume the speakers turned down and the volume the subwoofer turned down wasn’t parallel to each other and there was a certain point the subwoofer finally would kick in or drop off. For example at -35db on the Denon the subwoofer had very little output in comparison to the speakers. But with the volume at -25 or -20db then the subwoofer would be at an appropriate level to match the speakers. 

I am under the impression, and hope, that the MiniDSP outputs a signal equal to what it is receiving so is there a need for me to optimize the gain structure on the MiniDSP? And if so how would I perform this? One idea I had was to adjust the gain from the receiver to the amplifier just to the point of the clip light flickering. Then adding the minidsp in between the two and getting it to the same point where the clip light on the amp starts to flicker. Would this work well enough?

One more question. If, for example, I end up finding that having the subwoofer gain in the AVR at +6 and the gain on the amplifier at say -12 is the optimal level to have their gain matched what should I do when I run audessey and it turns the subwoofer down to -3 or -1 or whatever it may be. Should I turn the gain on the amplifier up the level that the receiver was turned down?
Thanks again for all your knowledge and sharing it with all of us!


----------



## Wayne A. Pflughaupt (Apr 13, 2006)

*Re: Gain Structure for Home Theater: Getting the Most from Pro Audio Equipment in Your System*


Thanks for the kind words, Devon. :T




DevonD said:


> The Peavey owner’s manual recommends keeping the gain dial turned all the way clockwise for “maximum headroom” and this is how I have always ran it. I have noticed that at lower volumes the subwoofer doesn’t seem to do much, I have felt the volume the speakers turned down and the volume the subwoofer turned down wasn’t parallel to each other and there was a certain point the subwoofer finally would kick in or drop off.


The information from the Peavey manual doesn’t make much sense. Any amp naturally gets its highest noise floor with the gains all the way up, so you actually get more dynamic range (defined as the “distance” between the noise floor and highest clean input signal) with the gain reduced. Of course, this assumes that the incoming signal is hot enough to begin with to accomodate lower gain settings.

As far as the inconsistent levels with various volume controls, I have no explanation for that. It sounds like some kind of signal gate is in play. If you don’t know what that is, it’s an effect commonly used in pro audio to shut the output signal down when the input signal falls below a certain threshold. For things like drum mics, for instance, to keep cymbals from bleeding into the snare drum mic when it’s not being hit. Check the miniDSP to see if has some kind of feature like this, and if so disable it.

In case you haven’t already, I’d set the Peavey’s back-panel filters for full range and let the AVR or miniDSP provide the low pass filtering.




> I am under the impression, and hope, that the MiniDSP outputs a signal equal to what it is receiving so is there a need for me to optimize the gain structure on the MiniDSP? And if so how would I perform this? One idea I had was to adjust the gain from the receiver to the amplifier just to the point of the clip light flickering. Then adding the minidsp in between the two and getting it to the same point where the clip light on the amp starts to flicker. Would this work well enough?


Like any other outboard equalizer, the miniDSP should not need any level settings to optimize gain structure. It should pass the signal straight through (along with whatever is added with any equalization, of course). So what you’d want to do is re-adjust the Peavey’s gain settings after the miniDSP is added to the signal chain, to accommodate any changes to gain the equalization brings.

My only concern is that the miniDSP, with only 2 Vrms capability, it might not have enough headroom to pass the signal level the Denon as actually capable of generating, and will clip. As noted in Part 7, the receiver I used while researching the article put out way more voltage than the manufacture claimed, so I wouldn’t put much stock in Denon’s spec.




> One more question. If, for example, I end up finding that having the subwoofer gain in the AVR at +6 and the gain on the amplifier at say -12 is the optimal level to have their gain matched what should I do when I run audessey and it turns the subwoofer down to -3 or -1 or whatever it may be. Should I turn the gain on the amplifier up the level that the receiver was turned down?


If you’re not happy with the sub level Audyssey generates, then I’d over-ride it and set it where you think it should be. If Audyssey won’t let you do that from the receiver specifically for the sub output, then it’s easy enough to change it on the back end – i.e., the amplifier gain controls. 

Hope this helps!

Regards, 
Wayne


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## corradizo (Jan 19, 2014)

http://www.avsforum.com/forum/155-d...52-minidsp-require-signal-boost-pro-amps.html

It sounds like if you have the balanced or unbalanced minidsp you should be fine. Do you have the audyssey dynamic volume on? It might help with the sub going quiet. 

What worked for me is setting the avr to 0db gain for the sub and then using an SPL meter with the avr pink noise on (still set to 0db) and turning the amp up/down until you hit 75db at the MLP. Then you can tune how "hot" your sub is based on the 75db reading (you should also do this with all your speakers btw, set the gains to 75db). I think audyssey does fine with distances, and corrections but it tends to set the gains terribly. My onkyo 609 varies 1 or 2 db per speaker in my media area, ymmv. A good mic or SPL meter is really helpful here. My 2cents.

Pete


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## DevonD (Apr 27, 2009)

*Re: Gain Structure for Home Theater: Getting the Most from Pro Audio Equipment in Your System*

Thanks Wayne and Pete for your feedback. 

Wayne, after reading the article my understanding was that the goal was to have the pre-out or subwoofer out gain within the AVR set just high enough that it is almost to the point of clipping at reference level. Is this correct? And with that level set in the AVR, then set the gain on the amplifier to the same point just before clipping so that like you said, they will start clipping at the same time. But if I were to then run audessey and it turned the gain down on one or more of my channels and to compensate I turned the gain up on the amplifier wouldn’t that throw out all of the gain structuring I just did? Or would it still be in acceptable range? 

I hope what I'm asking makes sense. Also, would REW with the tone generator be an acceptable substitute to the test disk with tones? Thanks again!


----------



## Wayne A. Pflughaupt (Apr 13, 2006)

*Re: Gain Structure for Home Theater: Getting the Most from Pro Audio Equipment in Your System*




DevonD said:


> But if I were to then run audessey and it turned the gain down on one or more of my channels and to compensate I turned the gain up on the amplifier wouldn’t that throw out all of the gain structuring I just did? Or would it still be in acceptable range?


As long as you’ve done the gain structuring exercise prior to running Audyssey, you’re good.

The idea of the gain structure exercise is merely to make sure that clipping sets in on the pre amp and outboard amplifier at the same time. At that point (as I noted in Part 9) you adjust all the speaker and sub levels as is normally done. It doesn’t matter if it’s done manually or via an auto-calibration system like Audyssey.

In other words, gain reduction at the various stages in the system post gain-structuring doesn’t ruin the gain structure, as no one runs their system at max anyway. Make sense?

Regards, 
Wayne


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## DevonD (Apr 27, 2009)

*Re: Gain Structure for Home Theater: Getting the Most from Pro Audio Equipment in Your System*

Yes I think it is starting to make sense. The purpose of having the gain all the way up in the AVR during the setup is just so that it will output its maximum signal before clipping and that signal is used to match the amplifier. After the initial setup the AVR doesn’t need to use its max signal anymore and can be set pretty much anywhere it needs to be correct? If the amplifier gain stays the same as what it was set to during the setup then no matter what gain the AVR is using (as long as it is below what the discovered clipping point is) both will still clip at the same time? 

Possibly very over simplified, but is that the general idea?


----------



## Wayne A. Pflughaupt (Apr 13, 2006)

*Re: Gain Structure for Home Theater: Getting the Most from Pro Audio Equipment in Your System*

Yes, that’s about it. And it's not "over simplified," it really is as simple as that. 

However, if you don’t like what Audyssey did to the sub level – say, cut it 3-4 dB from the AVR’s sub output - and if the receiver won’t let you re-adjust the sub level manually, you can just make it at the amp itself. It’s all the same in the end. It would be the same as if you’d gain-structured with a 3-4 dB lower signal from the sub output to begin with, so the amp’s gain settings would have been changed accordingly. Make sense?

Regards, 
Wayne


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## DevonD (Apr 27, 2009)

*Re: Gain Structure for Home Theater: Getting the Most from Pro Audio Equipment in Your System*

Great! That makes perfect sense. Thanks for explaining it. I have a lot of new things to try out and keep me busy this weekend. A Linkwitz transform, hard knee house curve and now optimizing the gain structure.

Thanks again, Wayne!


----------



## charlesp210 (Jan 20, 2010)

*Re: Gain Structure for Home Theater: Getting the Most from Pro Audio Equipment in Your System*

Thanks for these articles. For years I had used a Behringer DCX2496 to drive my power amplifiers. The 0dbfs corresponds to about 10V RMS, way too much for any power amplifiers I have (though one requires 5v RMS for actual clipping). Over at DIYAudio there is a thread on the DCX2496 and there are endless variations of modifications to get 0dbfs more "appropriate" to consumer hifi. One thing to do, for example, might be to attenuate the existing outputs by 6 or 10dB. I long ago determined this was not a good idea. The rated distortion of 0.002% only applies at 2V output. Before you get to 10V output, distortion has risen to 0.3% (not spec'd, this is my measurement). So you really want to keep output level from existing circuitry below 5v if not 2V anyway. Since I only use digital input to the DCX, I've never thought much about input levels. I didn't worry much about the S/N in digital domain given that I still have >16bits at -30dB, which seems to be like your argument.

But now I do something different in my main system, where I don't cut corners. Instead of using DCX as crossover for the midrange, I use a Behringer DEQ 2496. I create the required high pass filter using a pair of PEQ's that produce a perfect LR24. The DEQ gives me digital output which I run to a repurposed Onkyo RDV-1 as DAC. I like RDV-1 because it's well made piece with true PCM 1704 ladder DAC's.

This has completely changed the gain structure. Now, at 0dBfs I get barely above 2V output. That means I can't drive that amplifier to full voltage output…but it's still plenty loud enough. I had to dial down the remaining sub and super tweeter outputs from the DCX to match (subwoofer is dialed to maximum -15dB cut).

Incoming digital now plays at -10dB attenuation or less, often as little as -2dB (before it was -20dB). I watch the midrange and it never runs out of headroom, but much closer than before.

I like this a lot better, and I think it sounds a lot better. I play a lot of 24bit digital recordings, and I think this gain structure preserves the information much better than before.


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## Stratfordguy (May 26, 2011)

*Re: Gain Structure for Home Theater: Getting the Most from Pro Audio Equipment in Your System*

Hi Mr. Pflughaupt and all,

Let me start off by telling you that French is my first language so if i am unclear just let me know  


I was reading your post on using an avr with pro power amps and I have a few questions regarding how to do it with my setup.

Fisrt of all, I am using a Integra DTC 9.8 connected via XLR outputs to 3 Crown CTS600 amps. My speakers are 5 Martin Audio Effect 5 speakers that have an sensitivity of 95dB 1 Watt/1 metre. All that stuff in a 13x22 room.

If I am right, the way to calibrate a THX certified pre-pro to reference level is to get -30dB relative to full scale (0dB) that creates 75dB as measured with a C weighted SPL meter at the listening position. 

So, I set my front left speaker SP Level to 0dB, I start the internal pink noise signal and play with the gain of the Crown Amplifier until reading on the SPL meter is 75dB. After that, I set all the Crown amps inputs on the same page and calibrate the other channels using the SP Levels until each channel read 75dB. To acheive that, I am reducing the input level on the Crowns to +- 3/4.

But I guess, I am missing something as the reading on the amps are not near to lit the clipping light. I mearly got the -20dB light flashing...


As for the Crowns, the sensivity is 1.4V, the Voltage Gain is 31dB and it puts out 300W in 8 ohm. 

The amp is putting out 48.99 volts of output at full power (300=Voltage^2/8).

I Used "Voltage Gain (Av) = 20 * Log (Vout/Vin)" to found the voltage gain.

So to deliver full power, the pre-amp needs to put out 11.4V right?

Do my Integra is putting enough voltage to drive the Crowns?

If so, should I put up the gain on the amps and listen with the pre-amp to -XXdb? 

Thanks.


----------



## Wayne A. Pflughaupt (Apr 13, 2006)

*Re: Gain Structure for Home Theater: Getting the Most from Pro Audio Equipment in Your System*



Stratfordguy said:


> Do my Integra is putting enough voltage to drive the Crowns?
> 
> As for the Crowns, the sensivity is 1.4V, the Voltage Gain is 31dB and it puts out 300W in 8 ohm.
> 
> So to deliver full power, the pre-amp needs to put out 11.4V right?


No, the pre-amp only needs to put out 1.4V to drive the amp to maximum. I’m confident that the Onkyo can deliver that much.




> But I guess, I am missing something as the reading on the amps are not near to lit the clipping light. I mearly got the -20dB light flashing...


No, you aren’t missing anything. The situation is that your speakers are extremely efficient, and could be driven to ear-bleeding levels with less than 100 watts, yet your amp puts out 300 watts per channel. So you will never see high meter readings on the amp. If you drive that amp to maximum output with those speakers, you’ll probably be breaking windows and getting visits from the police.

Bottom line, you don’t have a problem with your amps or pre-amp. Everything is working fine. :T

Regards,
Wayne


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## Stratfordguy (May 26, 2011)

*Re: Gain Structure for Home Theater: Getting the Most from Pro Audio Equipment in Your System*

Is that what we call headroom to spare?


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## Stratfordguy (May 26, 2011)

*Re: Gain Structure for Home Theater: Getting the Most from Pro Audio Equipment in Your System*

By the way, thank you Wayne for that quick and straight to the point answer


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## Wayne A. Pflughaupt (Apr 13, 2006)

*Re: Gain Structure for Home Theater: Getting the Most from Pro Audio Equipment in Your System*

Thanks for the kind words, and yes that’s definitely headroom to spare – kilometers of it! 

Regards,
Wayne


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## bsinger (Feb 27, 2015)

*Re: Gain Structure for Home Theater: Getting the Most from Pro Audio Equipment in Your System*

Great Guide, Thanks!!

Results Report 

AVR Denon X4000

Max Preamp Output 7.14
Max Clean Output 4.2 (41% lower)

Right channel measured only


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## guofong (Feb 3, 2015)

*Re: Gain Structure for Home Theater: Getting the Most from Pro Audio Equipment in Your System*

Hi, Wayne: 

Thanks for the guide. My test results with EMOTIVA UMC-200:
https://drive.google.com/open?id=0B7-tKLkKnSm0VmpXdEEycDVtTnc

When measuring AVR subwoofer output voltage, you use 0 dBFS signal. Do we need to +10db for concerning about playing DOLBY/DTS LFE channel? Just like REW channel 4 add 10db output?


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## Wayne A. Pflughaupt (Apr 13, 2006)

*Re: Gain Structure for Home Theater: Getting the Most from Pro Audio Equipment in Your System*

Hi Guo,

Glad you liked the article. I’m afraid I don’t understand your question, and I certainly have no idea what REW has to do with adjusting gain structure. 

Regards, 
Wayne


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## guofong (Feb 3, 2015)

*Re: Gain Structure for Home Theater: Getting the Most from Pro Audio Equipment in Your System*

Thanks for the reply.

When I measure my AVP subwoofer channel maximum output voltage:

set Left and Right channel to small, set crossover at the highest possible frequency
set the AVP to Stereo mode
adjust the master level of AVP and the level for sub channel to max setting
Play 60 Hz Sine Wave 0 dBFS by Blu-Ray player(oppo 103d)->
send *PCM* to AVP(EMOTIVA UMC-200)->
measure the sub output voltage

But when I play a blu-ray movie with *DTS-HD/Dolby TrueHD*, *the LFE channel* is pre-set to play LFE data *10 dB higher than a main channel* (or 10dB higher than the bass from a main channel). I believe this is the reason that channel 4 output of REW is 10dB higher than other channels.

So my question is that, *for the maximum subwoofer output voltage when watching movie with DTS-HD/Dolby TrueHD encoded*, *do we need to add 10db with the subwoofer output measurement*?If we need to do this, how to do it? The file is already 0 dBFS.


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## Wayne A. Pflughaupt (Apr 13, 2006)

*Re: Gain Structure for Home Theater: Getting the Most from Pro Audio Equipment in Your System*

Okay I get it now, sorry for being so dense. 

You went through the process to measure the A/V processor’s subwoofer output, using a 0dBFS signal to get a voltage figure, right? So no, there is no need to add 10 dB to the subwoofer measurement. How do you add dB to a voltage figure anyway? 

Here’s the deal: 0 dBFS is the maximum signal the AVP is going to output anyway, right? It can’t generate +10 dBFS - there is no such thing (as far as I know anyway). So, the only way the +10 dB LFE sub output can be achieved is to _dial back the main channels_ by that much. Make sense?

Regards, 
Wayne


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## guofong (Feb 3, 2015)

*Re: Gain Structure for Home Theater: Getting the Most from Pro Audio Equipment in Your System*

Many thanks for the reply. This totally makes sense to me.

One more question regrading to the center output measurement:

https://drive.google.com/file/d/0B7-tKLkKnSm0VmpXdEEycDVtTnc/view
FL 3.45v
C/Pro Logic II music	3.3v
C/Pro Logic II cinema	5V
C/DTS Neo music	4v
C/DTS Neo cinema	5V

As my test results above, the max center output voltage is different when setting different playback mode. Using Pro Logic II music(3.3v) appears to be closed to FL channel output, but which test results is correct?


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## Wayne A. Pflughaupt (Apr 13, 2006)

*Re: Gain Structure for Home Theater: Getting the Most from Pro Audio Equipment in Your System*

Wow, that’s pretty peculiar. As to which figures are correct, if that’s what you measured with each mode (it never occurred to me to measure any way but with a total bypass!), then they both are correct, funny as that might sound. 

The question is though, which figure would you use for gain structuring your system? Obviously, the lower figure. If you gain structure with the Cinema figure, practically-speaking you could end up clipping things when you switch to the Music modes. Assuming you play music as loud as you do movies, that is (I don’t think most people do).

Regards, 
Wayne


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## guofong (Feb 3, 2015)

*Re: Gain Structure for Home Theater: Getting the Most from Pro Audio Equipment in Your System*

I totally forget to measure stereo(bypass) mode. Thank you!


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## guofong (Feb 3, 2015)

*Re: Gain Structure for Home Theater: Getting the Most from Pro Audio Equipment in Your System*

Hi, Wayne:

I went through the process for Gain Structure. 

The clipping indicator of my amplifier begins to blink when I increased the amplifier’s gain control to max. All the channel is the same situation, including my sub amp. Should I set my amplifier’s gain control to max? Is it a good idea to set gain to max? Could it be any danger? I usually set the gain control at around two-thirds of the maximum.

pre amp:EMOTIVA UMC-200
(L/C/R/LS/RS output maximum usable output:1.3v / sub maximum usable output:3.45V)
power amp for L/C/R/LS/RS:QSC DCA 1644/1222
power amp for sub QSC DCA 3022


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## Wayne A. Pflughaupt (Apr 13, 2006)

*Re: Gain Structure for Home Theater: Getting the Most from Pro Audio Equipment in Your System*

Certainly, the amplifier is going to clip if you turn up the gain controls. It’s perfectly normal. The volume got louder too, didn’t it? That means you’re pushing the amp harder. When amps are pushed too hard, they clip. Clipping shouldn’t be a danger – to the amp anyway (speakers, that’s another issue) – as most professional amps these days have detection systems to shut down if overstressed. However if you followed the gain structure process correctly, then the amplifier gain settings you ended up with are the ones you should use.

Regards, 
Wayne


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## corradizo (Jan 19, 2014)

*Re: Gain Structure for Home Theater: Getting the Most from Pro Audio Equipment in Your System*

Hi Wayne,

Great guide!!

If one has an AVR with its built in amp(s) driving their speakers and uses a pro-amp to drive their subs. Would this be the right procedure? 

Assumptions:
1. Clean output to reference. 
2. You have previously eq'ed your sub to where you like it .ie flat or with house curve etc.


1. Disconnect all speakers
2. Turn avr trim up on all speakers in avr
3. Play 0dbfs tone through all speakers, use "All Channel mode"
4. Crank avr to 0db (or cleanest level before distortion)
..now you have max voltage coming out of the avr's sub pre-out....
5. Turn your subs pro-amp input gain up until the indicator flickers red then goes solid red. (Note this setting, don't ever change it)
6. Rerun your room correction in the avr to set your speaker/sub trims in the avr OR use a spl meter to set your speakers and sub trims in your AVR, using your avr's built in tones so that each speaker and your sub are playing 75db at your listening position.
7.Enjoy


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## epk10 (Apr 23, 2016)

*Re: Gain Structure for Home Theater: Getting the Most from Pro Audio Equipment in Your System*

That was awesone


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## djcreative1 (Mar 16, 2019)

I read your thread on gain structure. Thank you for the information. I have two questions. In both finding out your avr's clean output and setting your amps gains you say to turn your subwoofers trim up all the way. However, you say "Adjust the AVR’s subwoofer trim level to the maximum setting" in one paragraph and "There’s no need to adjust the AVR’s subwoofer trim, as it will be automatically reduced to “clean voltage” when the AVR’s master volume is turned down to the “clean voltage” setting" in the next. This confuses me. Also, after your done setting your gain you say "All that’s left to do at this point is adjust all the AVR's speaker and subwoofer levels using your usual method". I dont have a usual method. I dont have audicy or any room correcting software nor do i want it. I want to set my sub trim to 0. That brings me to my first question. Can i do everything you said exept keep my subwoofer trim at zero? Im not opposed to turning it up to +15 i just have to know what to set it on after i set my gains. 0? Leave it at +15? My second question is similar to my first. When determining your clean ouput voltage you say to turn your xover to its highest setting. Can i do it with it on 80? Again, im not opposed to setting it to its highest setting, however, i would like to at least put that back to 80 when the test is done to protect my speakers. Thanks wayne!!!


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## djcreative1 (Mar 16, 2019)

Wayne A. Pflughaupt said:


> Please use this thread for any comments or discussion about my article Gain Structure for Home Theater.
> 
> Regards,
> Wayne


Im quoting you to hopfully notify you since this thread was last active 3 years ago.


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## Wayne A. Pflughaupt (Apr 13, 2006)

Hey dj,

Are you using outboard amplifiers in your system? If so, what make and model number?

Regards,
Wayne


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## djcreative1 (Mar 16, 2019)

Wayne!! Thank god your still on here!!! Yes. My receiver is a pioneer vsx-519v and that sub out is run via an rca y spliter to a crown xs900 amplifier.


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## Wayne A. Pflughaupt (Apr 13, 2006)

djcreative1 said:


> I read your thread on gain structure. Thank you for the information. I have two questions. In both finding out your avr's clean output and setting your amps gains you say to turn your subwoofers trim up all the way. However, you say "Adjust the AVR’s subwoofer trim level to the maximum setting" in one paragraph and "There’s no need to adjust the AVR’s subwoofer trim, as it will be automatically reduced to “clean voltage” when the AVR’s master volume is turned down to the “clean voltage” setting" in the next. This confuses me.


I was referring to the difference in level with _the main channels_ between the absolute maximum output vs. the maximum clean output, which will be less. I gave the example of 6.5 volts max vs. 5.5 volts clean, which is a 19% difference. For the subwoofer then, in this example, all you need to do is determine the maximum voltage and then subtract 19% to get the clean subwoofer voltage.

The only reason to worry about determining maximum clean voltage output is to get a vRMS figure, to determine if a professional amp you’re considering will be compatible. 




> Also, after your done setting your gain you say "All that’s left to do at this point is adjust all the AVR's speaker and subwoofer levels using your usual method". I dont have a usual method.


Sure you do. You do use some kind of method to adjust and match the levels of the main speakers, and then adjust the subwoofer to blend, don’t you? 




> That brings me to my first question. Can i do everything you said exept keep my subwoofer trim at zero? Im not opposed to turning it up to +15 i just have to know what to set it on after i set my gains. 0? Leave it at +15?





> When determining your clean ouput voltage you say to turn your xover to its highest setting. Can i do it with it on 80? Again, im not opposed to setting it to its highest setting, however, i would like to at least put that back to 80 when the test is done to protect my speakers.


The recommendations for maximum level and crossover settings is only for the purpose of determining the clean output voltage. Nothing more. 

Regards,
Wayne


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## djcreative1 (Mar 16, 2019)

Wayne A. Pflughaupt said:


> Sure you do. You do use some kind of method to adjust and match the levels of the main speakers, and then adjust the subwoofer to blend, don’t you?


No i dont. Thats what i thought setting your subwoofer gain was for. You set your amp to match the level of reciever aka other speakers so in a movie somone closing a car door doesnt sound like an explosion. I like leaving everything at 0 and using my volume. Cant hear dialog? Turn it up...explosions too loud? Turn it down. Untill i upgrade my receiver and get some software or understand it better im gonna keep doing it like this.

I would like to go through my gain setting process with you just to make sure i have it right. I get the idea, you want your reciver and amp to clip at the same time.

I will be using a oscope or dd1 to determine my clean output volume(not a speaker like you did). So (acording to you) i turn my sub trim all the way up(+15), turn my xover all the way up, play a test tone and turn up the volume untill it clips, back off untill it doesnt and thats my safe volume?

Then with my sub trim all the way up (still) and oxer all the way up (still), amp gain at 0 i play pink noise at the safe volume and increase gain until light is steady solid. Thats my gain.

Then since i like everything at 0 i would turn my trim back down to 0 and change my xover back to 80 and im done?

The reason why im asking is because when searching how to set your gains most information is about car audio. Its pretty much the same thing exept they recomend leaving everything flat instead of turning trim all the way up and xover. 


Since you know i will most likly put the subwoofer trim back to zero should i just set the gains with them set at zero? I want to get this right so i can set it and forget it! Thanks wayne!!!


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## Wayne A. Pflughaupt (Apr 13, 2006)

What speakers are you using for your main channels?

Regards,
Wayne


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## djcreative1 (Mar 16, 2019)

Wayne A. Pflughaupt said:


> What speakers are you using for your main channels?
> 
> Regards,
> Wayne


Mtx tp1200 for l,r
Then old pioneer satalite speakers that come with those 5.1 setups for c sl sr.


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## Wayne A. Pflughaupt (Apr 13, 2006)

Should have asked also (sorry!), what sub are you using?

Regards,
Wayne


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## djcreative1 (Mar 16, 2019)

Np! One channel will be ran to two nvx vsw152v2's (sealed) 2.4 cu ft per chamber 25oz poly fill each 2 ohm load. The other is a cheap 15 in a ported box tuned to 37. I think is 4.6 cu ft. The sub is a plpw15d. 2 ohm load. I also use a mini dsp for the high pass filter on the ported sub.


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## Wayne A. Pflughaupt (Apr 13, 2006)

djcreative1 said:


> I would like to go through my gain setting process with you just to make sure i have it right. I get the idea, *you want your reciver and amp to clip at the same time.*


Actually, your situation is outside the scope of the article. The article is based on the premise of using outboard pro-audio amplifiers for all channels. 

What you’re basically doing is setting your subwoofer level. The common procedure for that, which you’ll find recommended at any home theater forum, is to adjust the subwoofer gain to get an in-room SPL measurement about 10 dB hotter than the main speakers, as a starting point. True, typically the sub in question is active, but it doesn’t change if your sub happens to have an outboard amplifier. An amp is an amp - makes no difference if it’s in or out of the sub box. And a gain control is a gain control. 

At the end of the day, all that matters is: are you able to get all the volume you need out of the sub? If the answer is “no,” even with the receiver’s sub output maxed out, and the sub’s gain all the way up, then a new sub system in order. If the answer is “yes,” you’re good to go.

I’m sure you won’t be satisfied with that, so consider this. In your situation, a pro-audio-styled gain structure exercise is irrelevant because your receiver, despite Pioneer’s specs, probably puts out less than an honest 100 watts per channel, while your Crown amp puts out 1200 watts per channel with your 2-ohm load. IOW, by the time the Crown reaches clipping, the Pioneer will be having a melt-down because it can’t keep up.

So, you can do the max-level procedure you mentioned, at +15 or 0 (your choice), but what you’re probably going to find is that the sub ends up exceeding loud compared to the main speakers. Which means you’ll have to back down on the amplifier gain. Which means all you’ve ultimately done is blend the sub with the main speakers, just as I described in the second paragraph above.

Regards,
Wayne


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## djcreative1 (Mar 16, 2019)

Wayne A. Pflughaupt said:


> [
> 
> 
> So, you can do the max-level procedure you mentioned, at +15 or 0 (your choice), but what you’re probably going to find is that the sub ends up exceeding loud compared to the main speakers.


Perfect!!! As long as theres no damage to my subs or im not sending them a dirty signal id prefer it to be bass heavy. Hell im purposly picking out bass heavy movies just to hear my subs. Im sure ill want better sq later in life but for now all i wanna do is BUMP!!! 

Just to be perfectly clear the "max level procedure" your talking about is the one i mentioned to you right? 

Im soo excited!!! Thanks for your time and info! 

Btw i call you "young wayne" in my head. Lil wayne refers to himself as that in a song and i think of it everytime you reply! Haha peace!


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## Wayne A. Pflughaupt (Apr 13, 2006)

> Just to be perfectly clear the "max level procedure" your talking about is the one i mentioned to you right?


Yes indeed. :T

Regards,
Wayne


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## djcreative1 (Mar 16, 2019)

Wayne A. Pflughaupt said:


> [quo


Say wayne, what if your speakers (left right) on your avr clip at a lower volume than your subwoofer pre out? Would you set your external amp (for subwoofer) gain according to the safe volume before speakers on the avr clip ( since you wont go past that volume anyway) or the safe volume before the avr's subwoofer pre out clips? I dont know if my speakers clip at a lower volume than my pre out im only asking because i know its the case for most car audio head units. I wont know till the first when my oscope comes in if its the case for me. Either way, whats the correct answer?


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## Wayne A. Pflughaupt (Apr 13, 2006)

If the mains distort before the sub amp clips, then the sub system obviously has more power than the mains. As such, there’s no gain structure requirement because you’ll never drive the sub amp into clipping in normal use, or even in “abusive use” where you were intentionally driving the mains to distort. So simply adjust the receiver’s sub output and the sub’s gain knobs appropriately to match and blend with the main speakers.

Regards,
Wayne


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## djcreative1 (Mar 16, 2019)

Wayne A. Pflughaupt said:


> If the mains distort before the sub amp clips, then the sub system obviously has more power than the mains. As such, there’s no gain structure requirement because you’ll never drive the sub amp into clipping in normal use, or even in “abusive use” where you were intentionally driving the mains to distort. So simply adjust the receiver’s sub output and the sub’s gain knobs appropriately to match and blend with the main speakers.
> 
> Regards,
> Wayne


Ok. Got my oscope in today. As expected my right left speaker terminals on my receiver clip at volume 64/80 and the sub out 73/80. So to be clear i would set my external subwoofer amplifier's gain with the safe volume of 63 not 72 correct? 

Btw for anyone googling when the pioneer vsx-519v-k receiver clips it is @ volume 64/80 for left and right speaker terminals and 73/80 for subwoofer out. 

Thanks a"gain" wayne!!!


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## Maxino1969 (Dec 12, 2019)

I bought the minidsp 2x4hd to equalize my 3 sub woofers in my home Theater, by specifications the minidsp has for the analogue input a jumper that set 2vrms (defaul) or 4 Vrms, All 4 output from the minidsp to the subwoofer are fixed at 2vrms . I measured the sub output of my avr denon 3500h and found to be 3.2vrms (0 Master Volume, 0 trim sub on avr, REW 0db on HDMI-channel 4, No Audyssey). my stupid questions are:

Do I have to set the jumper on the minidsp to 4Vrms or should / can leave it at 2Vrms. Which is the best option?
In both cases, what should I set on the Avr and / or minidsp? If I leave 2vrms I should have clipping of the signal when the avr sends more than 2v .. if I set 4Vrms on the minidsp, I should have more attenuation of the signal.. and then increase the trim on the subs? I'm going crazy and I don't even know if I should worry about it! One thing that I understand, is putting the minidsp in the chain the volumes of the sub woofers are lowered (i didn't misuse yet but approximately from 2v to 4v about 6db..and from no minidsp to minidsp..much more!).
Can you suggest me how to set the best ... Thanks a lot of the time that you lose reading my post.

My configuration is :
avr sub out 1 -> minidsp 2X4HD input 1 -> 3 subwoofer out.
Thanks.


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