# Help matching receiver with pro amp



## vmpty (Oct 6, 2010)

I'm building a new 5.1 HT. 

- My fronts are Def Tech BP7001, center is CLR3000 and the 2 BPVXs for surrounds. All are around 92dB in sensitivity, 8 Ohms, and max amp power recommended is 400W.

- Long story short I tried to buy the Denon AVR 990 but will be getting a 4310 instead. I read in a test that the actual power out at 8 Ohms was about 100W if my memory serves me right.

I want external amp(s) to power the front three speakers and leave the receiver to handle the 2 surrounds and possible future expansion to 7.1 I had been studying several amps but for different reasons I almost made my mind on Yamahas P3500S. They can put out 350W at 8 Ohms in stereo, so 2 of them would be my choice, leaving one channel free.

Here is the deal, the pre amp outputs of the 4310 are rated at 1.2V. The Yamaha P3500 inputs are described: <Sensitivity> at 8 Ohms, Att Max : +4dB.

Does it mean that the pre amp output signal level is not going to be enough? Not sure how to interpret the Volts from the pre amp Vs the dB at the amp inputs.

I've read that I may not get a good sound (Hiss, etc) or any sound at all from the amp and it would require another box in between them to boost the pre outs signal (Art Clean box for example). I would prefer not to have to do this. Can anybody help me confirm if it will be a must if I go with the Yamaha P3500S?


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## vmpty (Oct 6, 2010)

Well it happened again, I cannot find the answer to a question, I post it and minutes later... I find the answer! It was quite interesting though, and it seems the connection will be OK.

In a nutshell, "A rating of +4 dBu in equipment specifications implies a reference or nominal voltage of 1.23 volts. The formula for calculating dBu is 20log (V2/V1) where V1 and V2 are your two voltages. Then 20log (1.23/0.775) = +4 dBu."

I would post the link for the complete explanation but I'm not able to post links yet.


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## bambino (Feb 21, 2010)

Good choice in AVR's, i've always been a fan of Denon. To answer your question, i know alot of folks on this site use pro amps running off there AVR's with no problem, weather they are using them out of the main Preouts or the Sub out. I would give it a try without anything inbetween as it sounds like your set on your Amps of choice if you have to add a box inbetween it wouldn't be a huge deal. 

However i am highly optimistic that you won't have any issue's as there are also several folks on here that use up to 4 Amps just off of the Sub out (i plan on using possibly 6). I'm sure others will chime in to give better answers, there are also Threads on this topic (1 started by me) that may better answer your question.

One reccomendation i have on your choice of AVR's is since you are planning on running outboard Amp's then maybe get a lesser model with Preouts and put the saved cash into other parts of your system. JMO.:T


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## vmpty (Oct 6, 2010)

Thank you for your comments Bambino. I agree with you, actually my plan of a lesser amp was the AVR-990. I got a great deal on one for $649 but UPS "lost" it. JR had no more of those so they offered me such a good deal on their last 4310 that I took it. I was not even considering it before.


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## bambino (Feb 21, 2010)

Can't beat a good deal when they come around i was actually concidering one for my next AVR but i keep juggleing brands in my head i'm not sure which i'll get next. Be sure to post your results and findings after you have everything up and running. Hope you enjoy your new getup.:sn:


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

vmpty said:


> Here is the deal, the pre amp outputs of the 4310 are rated at 1.2V.


In my experience, those manufacturer pre-amp voltage output ratings are out to lunch. My Yamaha RX-V1 is rated for a paltry 1V. However, I made a test disc with 0 dBFS signal at 1 kHz, and with the receiver’s volume turned all the way up I measured _over 4 volts._ This is probably why most people don’t seem to have any problems using pro amps with their receivers, despite the supposed mismatched levels.

Regards,
Wayne


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## tcarcio (Jun 27, 2007)

With my Pioneer I needed to add the samsons in order to get the amps to perform correctley but in your case it seems all will be fine. It does bring up a question that I hope you don't mind me asking here. When I switched to the Marantz reciever I just hooked it all up the way it was with the Pioneer. If the Marantz already has enough voltage that they don't need the Samsons then will I cause a problem by useing them anyway. I would think it wouldn't matter since I would have to adjust the levels differently then with the Pioneer in line but I am not sure.


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## bambino (Feb 21, 2010)

Wayne A. Pflughaupt said:


> In my experience, those manufacturer pre-amp voltage output ratings are out to lunch. My Yamaha RX-V1 is rated for a paltry 1V. However, I made a test disc with 0 dBFS signal at 1 kHz, and with the receiver’s volume turned all the way up I measured _over 4 volts._ This is probably why most people don’t seem to have any problems using pro amps with their receivers, despite the supposed mismatched levels.
> 
> Regards,
> Wayne


I'm curious about how you took your mesurement Wayne, what tools and how you went about it other then the test disc. Would like to test mine.
Thanks, bambino


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

I downloaded a sine wave test tone from our BFD Guide. I used 1 kHz, but I’ve learned since then that 60 Hz is better because that’s the frequency volt meters are calibrated for. IOW, 60 Hz should get the most accurate reading.

I dropped the sine wave into Audacity and increased the gain to -0.25 dBFS (i.e. ¼ dB below 0 dBFS). I also cut and pasted the signal to extend the time to about one minute (to give plenty of time to take a measurement with the meter). Getting the signal to 0 dBFS (or really close to it) is key since that’s the maximum signal strength a CD or DVD player can generate. _*In order to determine what the receiver’s maximum output voltage is, you have to have a maximum input signal.*_

After that I saved the modified sine wave to a WAV file and burned it to a disc, loaded the disc into my CD player, and turned the receiver’s volume all the way up. Of course, make sure the speakers are unplugged, the receiver set for 2-channel stereo, and speakers set for Large. With the receiver turned all the way up, you can take a measurement with a volt meter from an RCA cable plugged into the left or right output jack, reading across the connector’s tip and sleeve. The meter should be set in a low range for AC voltage.

The value you measure can be cross-referenced to a pro audio amp’s input sensitivity specification. The amp I had on hand for evaluation had a sensitivity rating of 1.0 vRMS, and I was able to activate its clipping indicators with a measurement at the AVR’s outputs of 0.8 volts. As they say, close enough for government work! :T

If I ever get around to finishing the article on gain structure I’m working on, I hope to have a 60 Hz, 0 dBFS signal that can be downloaded to make things easier (i.e., no need to fiddle with all the tweaking in Audacity). But for now this will do.

Regards,
Wayne


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## bambino (Feb 21, 2010)

Thanks Wayne i'm looking forward to trying this, just sounds like one of those fun things to do.:nerd:


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## ojojunkie (Jun 23, 2010)

Several years back when I started my HT hobby, I had Denon AVR-2802 mated with Paradigm Studio Reference v.2. during that time the sound was fine except that the bottom end was somewhat lacking. Was able to get B&K ST-1400 power amp 105 watts/c and didn't have any problem between denon & B&K. So, I believe denon has better voltage output mate seamlessly with external amp.


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## vmpty (Oct 6, 2010)

Wayne A. Pflughaupt said:


> I hope to have a 60 Hz, 0 dBFS signal that can be downloaded to make things easier



Would something like this work? http://www.ronelmm.com/tones/


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

Great site. Yes that will work. However, I ran the 60 Hz tone through Audacity found that it’s ~1.75 dB below 0 dBFS. So whatever volt reading you get from your pre amp output, you could assume it’s doing a bit better than that.

Also I’ve been informed by an EE that some voltmeters will read AC voltage as peak volts, and some will read RMS, which will be a lower figure. So check your meter’s manual to see what it does. 

Regards,
Wayne


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## JerryLove (Dec 5, 2009)

I have a P5000S running off the pre-outs of an Integra AVR using a simple RCA-XLR converter from BestBuy. In a perfect world I would use a proper converter box to adjust voltage; as is the effect is that I seem to be -6db from a proper pro-connector.


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## bambino (Feb 21, 2010)

JerryLove said:


> I have a P5000S running off the pre-outs of an Integra AVR using a simple RCA-XLR converter from BestBuy. In a perfect world I would use a proper converter box to adjust voltage; as is the effect is that I seem to be -6db from a proper pro-connector.


Is there such a thing as a proper voltage converter box and where would a guy find one? Thanks, Bambino.:T


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## vmpty (Oct 6, 2010)

*If required*, this would be one http://www.artproaudio.com/products.asp?id=77&cat=13&type=90

They match the difference in impedance to increase the signal level.

There is also a Samson unit here http://www.samsontech.com/products/productpage.cfm?prodID=1699
According to users who have both, and supposedly made frequency response measurements (Flat response all the way to 10 Hz without mods), the Samson is better and cheaper.

Please note I have no personal experience with either.


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

bambino said:


> JerryLove said:
> 
> 
> > I have a P5000S running off the pre-outs of an Integra AVR using a simple RCA-XLR converter from BestBuy. In a perfect world I would use a proper converter box to adjust voltage; as is the effect is that I seem to be -6db from a proper pro-connector.
> ...


In most cases, the only reason to get a signal converter is if your AVR doesn’t generate enough voltage to drive the amp. You can perform the exercise I outlined in Post #9 to see what your AVR’s output voltage is. It’s explained in more detail in Part Seven the gain structure article I recently finished (link in my signature), along with some test signals you can download to perform the exercise. Once you know your AVR’s output voltage you have something to compare to the amplifier sensitivity specs to get an idea of compatibility between the two.

Being “-6 dB from a proper pro connector” is merely an issue of where the amp’s gain controls must be set. It’s no big deal if they have to be set higher when being driven by an AVR than they would in a pro system.

Regards,
Wayne


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## bambino (Feb 21, 2010)

Thanks guys, i am gonna see what my AVR will do without a converter first then probly do the test.I'm kind of curious if has power to drive signal to 4 possibley 6 amps.


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## JerryLove (Dec 5, 2009)

Wayne A. Pflughaupt said:


> Being “-6 dB from a proper pro connector” is merely an issue of where the amp’s gain controls must be set. It’s no big deal if they have to be set higher when being driven by an AVR than they would in a pro system.


 In fairness: It means your max volume is 6db less than what it otherwise would be *if* we assume that the amp could drive the speakers 6db higher but the pre is maxed-out.

In reality: It's unlikely that one will need that last 6db (that the amp and pre-amp would both be running full out and the amp would have unused headroom left, and that it would also be "too quiet")... that's why I'm not using anything to correct it on my own rig. I did say "in a perfect world".

I think your plan is sound. Try it with just the XLR-RCA converter (Wayne wrote an excellent few posts on pro amps) and see if you are happy with it. I think you will be.


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## gsmollin (Apr 25, 2006)

Wayne A. Pflughaupt said:


> In my experience, those manufacturer pre-amp voltage output ratings are out to lunch. My Yamaha RX-V1 is rated for a paltry 1V. However, I made a test disc with 0 dBFS signal at 1 kHz, and with the receiver’s volume turned all the way up I measured _over 4 volts._ This is probably why most people don’t seem to have any problems using pro amps with their receivers, despite the supposed mismatched levels.
> 
> Regards,
> Wayne


That 1 V spec may depend upon outboard loading, and whatever harmonic distortion spec was attendant to the drive level spec. A single-ended output may show increased even-order harmonics when over-driven. This is often a gradual degradation, and while technically-out-of-spec, it isn't noticeable to the ear. In addition, there is almost always a margin between spec and actual performance that the design engineer left in for production spread. So one example of a given preamp may have a greater drive than one built a few months later with different parts. Both are in-spec, however.


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## Lucky7! (Jan 7, 2008)

Wayne A. Pflughaupt said:


> In my experience, those manufacturer pre-amp voltage output ratings are out to lunch. My Yamaha RX-V1 is rated for a paltry 1V. However, I made a test disc with 0 dBFS signal at 1 kHz, and with the receiver’s volume turned all the way up I measured _over 4 volts._ This is probably why most people don’t seem to have any problems using pro amps with their receivers, despite the supposed mismatched levels.
> 
> Regards,
> Wayne


That's because it's another example in the domestic world of a 'worthless spec'. An AVR has so many various inputs and ways of adjusting the level that you would need to specify the entire signal path settings to give a meaningful number; anything else is just plucked out of the air.

In the broadcast world, an item like an AVR would, or at least should, have a more complete set of specs, defining at least how they came to that number. For example (made up specs): 
SPDIF/AES Input: 0dBFS with VC at -20dB gives 0dBV (@ xx THD) at Line Out
Analogue Inputs: 0dBV in with VC at -20dB gives 0dBV (@ xx THD) at Line Out
Line Out: max level +10dBV into 10kΩ (@ xx THD)

The above tells me, the conditions the specifications were derived from, the amount of gain in the analogue line stage (20dB) and the maximum level and what load it was driving at the time.

That is useful, but AVR output specs aren't and trying to discern something from them without measuring won't give you anything worthwhile, as you own example shows.




JerryLove said:


> I have a P5000S running off the pre-outs of an Integra AVR using a simple RCA-XLR converter from BestBuy. In a perfect world I would use a proper converter box to adjust voltage; as is the effect is that I seem to be -6db from a proper pro-connector.


You're only driving one phase of the balanced line into the amp so that's why you're 6dB lower in gain. <_ this also relates to post # 19.


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## JerryLove (Dec 5, 2009)

A9X said:


> You're only driving one phase of the balanced line into the amp so that's why you're 6dB lower in gain. <_ this also relates to post # 19.


 No, that would be 3db.

Consumer audio uses a sine wave with a maximum amplitude of 0.447v while a pro audio signal is 1.737v max amplitude.

In theory (and perhaps i should pull out a meter and check) I should actually be dealing with a 14db difference.


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## Lucky7! (Jan 7, 2008)

JerryLove said:


> No, that would be 3db.


No, it's 6dB. 20*log1/2=-6dB. At the input of an amp, you are dealing with voltage, not power.



JerryLove said:


> Consumer audio uses a sine wave with a maximum amplitude of 0.447v while a pro audio signal is 1.737v max amplitude.


There is no standard for levels in consumer audio, and in pro gear, the levels intended are defined in the spec, or at least they should be. There is no pro gear I have ever seen limited to a max peak voltage of 1.737V/1.22Vrms. Greater than +20dBV levels are common.

Voltage specs for audio gear are universally given as RMS, not peak.



JerryLove said:


> In theory (and perhaps i should pull out a meter and check) I should actually be dealing with a 14db difference.


Going on the two numbers you provided, 20*log(1.737/.447)=11.79dB


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

JerryLove said:


> No, that would be 3db.


Scroll down to “Unity Does Not Always Equal One.”
http://www.rane.com/note124.html

Regards,
Wayne


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## JerryLove (Dec 5, 2009)

A9X said:


> There is no standard for levels in consumer audio, and in pro gear, the levels intended are defined in the spec, or at least they should be. There is no pro gear I have ever seen limited to a max peak voltage of 1.737V/1.22Vrms. Greater than +20dBV levels are common


 I find that claim so incredible as to defy belief. Without a standard level (admittedly approximate) volume changes when switching sources would be uncontrollable. I would swith from a rock song on my cd player i could not hear to a rock dvd-a on my vs player and blow my speakers because of the high volume.



> Voltage specs for audio gear are universally given as RMS, not peak.
> 
> Going on the two numbers you provided, 20*log(1.737/.447)=11.79dB


 if RMS would make you happy:
consumer 0.316(approx)
Pro lapprox(approx)

At least in the us. In germany line levels are 1.550 vrms


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

JerryLove said:


> I find that claim so incredible as to defy belief. Without a standard level (admittedly approximate) volume changes when switching sources would be uncontrollable. I would swith from a rock song on my cd player i could not hear to a rock dvd-a on my vs player and blow my speakers because of the high volume.


Check out the specs of some pro audio gear. Most processors can handle +22 dBu and mixing consoles can generate signals as high as +26 dBu.

Keep in mind, that has no bearing in the consumer signal chain, even if pro gear is being used. The pro gear may be capable of accepting/passing signal levels that high, but the consumer front end will never generate a signal that high. So there's no danger of blowing your speakers. 

Regards,
Wayne


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## JerryLove (Dec 5, 2009)

Wayne A. Pflughaupt said:


> Check out the specs of some pro audio gear. Most processors can handle +22 dBu and mixing consoles can generate signals as high as +26 dBu.
> 
> Keep in mind, that has no bearing in the consumer signal chain, even if pro gear is being used. The pro gear may be capable of accepting/passing signal levels that high, but the consumer front end will never generate a signal that high. So there's no danger of blowing your speakers.


 I can agree with all of this. I disagree with the other poster who said there was no consumer standard (though i readily acknowledge that the standard is not followed tightly, but is rather approximate )


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

Hate to break it to ya, but A9X is right. :hide: Shocked me too! Scroll down to “Dynamic Range and Signal –to-Noise" (Signal-to-noise paragraph).

http://en.wikipedia.org/wiki/Audio_system_measurements

Regards,
Wayne


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## JerryLove (Dec 5, 2009)

http://en.wikipedia.org/wiki/Nominal_Level


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