# Is Full Range EQ a no go?



## Orange55

As many have said before me the knowledge on this web site is fantastic and I have read with interest and put into practice lots of the techniques I have seen online, house curve, min number of filters etc ...

However, there is one area which appears not be to addressed and that is Full Range EQ, everything appears to focus around the 20hz to 200 hz. I have worked on getting the full range from 20hz to 20Khz smooth and with great effect I believe from what I hear on my 5.1 system using the ECM8000 mic and XENYX preamp.

But am I doing something which should be avoided?


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## brucek

> am I doing something which should be avoided?


A couple of issues here.

The first is the quality of the EQ you're using. If it's a BFD or the like, then there are issues of noise floor introduced along with concerns over the quality of the full conversion through the ADC and DAC chain.

Second is the tendency of many to try and use other than very low Q filters. Trying to adjust peaks and dips at higher frequencies is problematic unless you placed your head in a vise while listening. Only very broad filters should be used.

brucek


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## Wayne A. Pflughaupt

> However, there is one area which appears not be to addressed and that is Full Range EQ...


I keep meaning to do a write-up on the subject...

In the mean time, you can find some good info on the topic at this thread.



> I have worked on getting the full range from 20hz to 20Khz smooth and with great effect I believe from what I hear on my 5.1 system using the ECM8000 mic and XENYX preamp.


What are you equalizing with?

Regards,
Wayne


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## Orange55

Hi Guys, thanks for the guidance, very helpful and I have now made changes based on your advise.

Firstly I am using a Tag Mclaren AV32R to do the EQ, with Linn Ninka mains and a B&W PV1 sub. My Centre and Surround are the matching set to the Linn fronts.

I spend 80% of my time listening to 2 channel music, hence my desire to eq the mains, I don't use the sub with music as the mains go down to 50Hz. Any assistance would be great.

Here is my fronts before and after with the eq used, I removed some of the 300hz plus at the weekend with no adverse effect to the actual sound.


*Front Left - No EQ*








*Front Left - with EQ*








*Front Left - Settings:*
71Hz -3.0 10.0
105Hz -10.5 3.8
147Hz 5.4 2.3
191Hz -7.5 5.8
4700Hz -3.0 1.1



*Front Right - No EQ*








*Front Right - with EQ*








*Front Right - Settings:*
72Hz -3.0 1.3
131Hz 3.7 5.1
175Hz -5.5 5.1
222Hz 5.5 3.4
290Hz -3.0 5.1
4700Hz -3.0 1.1




Finally my sub has rather two drastic drops that I have been unable to do anything about, from moving he sub changing phase and EQ etc; Overall I think the sub graph looks good, but wondering if there are any secret tricks. Plus there are far to many filters, but I can't seem to reduce them and still get the desired response.


*Sub - no EQ*








*Sub - with EQ*









*Sub - Settings:*
21Hz 2.0 4.3
33Hz -3.1 3.1
41Hz 5.0 3.7
57Hz 4.0 5.0
61Hz 4.0 3.4
72Hz -8.6 3.9
97Hz -14.5 2.2


Thanks in advance.


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## weverb

Wayne is definitely your man to help guide you through eq'ing your mains. He has been a great mentor to me through my journey of eq'ing my entire 5.1 set-up. As brucek stated... be sure to use only wide/broad filters. 

Looks good so far! :bigsmile:


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## Wayne A. Pflughaupt

Thanks for the kind words, weverb!



Orange55 said:


> I spend 80% of my time listening to 2 channel music, hence my desire to eq the mains, I don't use the sub with music as the mains go down to 50Hz. Any assistance would be great.


Does the Tag use FIR filters? It’s curious that the left and right graphs look so different, both before and after EQ.

What’s with the peculiar Target curve? I’d want response out to 20 kHz, if the speakers are capable of generating it. Is the Tag causing that roll out? 

The Target curve for the sub, I’d suggest shelving at ~30 Hz rather than 50 Hz, if you have enough headroom. Also, why did the sub’s Target change from 72 dB to 80 dB?

It looks like most of the sub filters are indeed needed. It’s a shame you can’t get better before-EQ response from the sub. If there are some other placement options you haven’t explored yet, I’d surely look at them, especially a corner, if there is one available. A sub with 8” drivers usually needs all the help it can get.

Regards,
Wayne


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## Roger Dressler

Wayne A. Pflughaupt said:


> Does the Tag use FIR filters?


2nd order IIR biquads, per John Mulcahy.


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## Orange55

Wayne A. Pflughaupt said:


> Thanks for the kind words, weverb!
> 
> Does the Tag use FIR filters? It’s curious that the left and right graphs look so different, both before and after EQ.
> 
> What’s with the peculiar Target curve? I’d want response out to 20 kHz, if the speakers are capable of generating it. Is the Tag causing that roll out?
> 
> The Target curve for the sub, I’d suggest shelving at ~30 Hz rather than 50 Hz, if you have enough headroom. Also, why did the sub’s Target change from 72 dB to 80 dB?
> 
> It looks like most of the sub filters are indeed needed. It’s a shame you can’t get better before-EQ response from the sub. If there are some other placement options you haven’t explored yet, I’d surely look at them, especially a corner, if there is one available. A sub with 8” drivers usually needs all the help it can get.
> 
> Regards,
> Wayne


Hi Wayne

Thanks for your feedback, it appears I have made a couple of school boy errors.

Firstly I have applied a house curve to my mains, whereas they should be flat and the house curve onto the sub. 

As for the overall response from the mains I wonder if it is the position of the speakers that could be causing that.

The sub levels are different as I uploaded an old graph for the non-eq.

So next steps are to apply all of the learning from above and from the other thread and will post my new measurements for review and a picture of the actual room as that may help with any odd readings.

Thanks again


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## Orange55

Ok lets try again, staring with the sub.

Here are the pre and post eq graphs reflecting the new roll-off. Sadly again using 8 filters.


*Sub Without EQ*








*Sub With EQ*









*Sub Settings:*
20Hz 4.0 1.8
34Hz -3.1 6.0
41Hz 5.3 5.0
44Hz 5.0 3.2
60Hz 6.0 6.3
72Hz -13.0 5.0
90Hz -8.9 3.0
103Hz -7.6 3.0



Here is the room in which the speakers sit, to see if this explains why the fronts are so different pre and post eq.

*System*









And here are the graphs for the fronts:

*Front Left Without EQ*








*Front Left With EQ*








*Front Left Settings:*
45Hz 4.5 4.6
46Hz 4.5 6.3
54Hz 5.0 1.8
70Hz -12.2 6.9
104Hz -11.6 2.1
131Hz 5.0 3.9
156Hz 5.2 7.8
186Hz -2.2 6.0




*Front Right Without EQ*








*Front Right With EQ*








*Front Right Settings:*
50Hz 5.0 5.0
53Hz 5.0 5.0
55Hz 5.0 5.0
70Hz -10.9 4.0
89Hz -3.6 2.0
126Hz 4.6 5.7
172Hz -2.6 5.6
214Hz 5.0 10.0


Any help and comments are more than welcome, the main issue I see if far to many filters and I hope some person with more experience may be able to guide me in the right direction.

Thanks


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## weverb

On your mains, couldn't the first three filters on each main be done with one filter with a larger bandwidth?

Also, looking at your picture, you are dealing with the same issue as me, no room symmetry around the mains. Therefore, they are going to respond/perform differently.


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## brucek

> graphs reflecting the new roll-off


I'm as baffled as Wayne by your sub target.

It's as if you've baked in a peak. I've circled the drop off that you've programmed in. Can you discuss why you do this. It results in a peak at 30Hz........ It's exactly what we're attempting to avoid.








Below is a more conventional house curve.
It's an log interpolated 8dB rise from 70Hz to 30hz.








brucek


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## Orange55

Hi brucek

I can imagine your thought when you saw the graph .

I have clearly miss understood what I had read on the house curve. I see my mistake now. What great service you get here. 

I think I can see why I made that mistake and I am probally very well positioned to write a dummies guide to eq given the basic errors I have made.


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## Orange55

weverb said:


> On your mains, couldn't the first three filters on each main be done with one filter with a larger bandwidth?
> 
> Also, looking at your picture, you are dealing with the same issue as me, no room symmetry around the mains. Therefore, they are going to respond/perform differently.


I'll see if I can do that, thanks.


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## brucek

> miss understood what I had read on the house curve


Yeah, the file of the jpg I posted is a simple:

30 8.0
70 0.0

You're just trying to boost the bottom end a bit, but usually you'll stop at 30Hz. It's generally a good idea to tick the log interpolate feature checkbox which draws a straighter line between your points, otherwise it will hump up between points and sound a bit bloated.

The pic below shows the difference between a normal 80Hz crossover target and then compares it to a 5dB house curve. You can see the boost in the target. The new target line will be used by REW to recommend its filters.









brucek


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## Wayne A. Pflughaupt

Orange55 said:


> As for the overall response from the mains I wonder if it is the position of the speakers that could be causing that.


Judging from your picture, I’d say so:










The left speaker, it’s the corner that’s causing the boost in the 70-100 Hz range to be worse than on the right.

Good looking system, by the way – I’m drooling!

Since the processor is using traditional IIR filters (thanks for the info Roger), I think it’s over-equalizing. First, I’d loose all the boosted EQ settings below the crossover frequency for both channels. That's the subwoofer's territory.

For the left channel, the narrow 131, 156 and 186 Hz filters are all “fighting” the overly broad filter at 104 Hz. “Equalizing the equalizer,” in other words. Rather than using two closely-spaced filters at 104 and 70 Hz, I’d try a single, broader filter at 70 Hz or a bit lower. That would pull down the 70-100 Hz peaks without “digging in” to the frequencies above that point. A side benefit would be that the same filter would also reduce the 40 Hz peak.

For the right channel, the same thing. A single broader filter south of 70 Hz will bring down that peak with minimal effect on upstream frequencies. The 172 Hz filter isn’t needed, but something in the 125 Hz range might be after applying the <70 Hz filter. The 214 Hz filter is way too narrow and boosted too much – I’d lose it.

That said, it wouldn't hurt to save the processor's settings so you can compare them to my recommendations. Use the ones that sound better to you.

For your sub, I’d say it’s probably your placement that’s killing you. Will it fit in that corner behind the left speaker? Corner placement often works wonders in asymmetrical rooms like yours. It should boost your output and get you better extension, and any response anomalies will probably be easily equalizable (unlike with your current placement).

Regards,
Wayne


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## weverb

Told ya Wayne was "The Man" when it comes to eq'ing the mains. :bigsmile:


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## Orange55

Wayne A. Pflughaupt said:


> Since the processor is using traditional IIR filters (thanks for the info Roger), I think it’s over-equalizing. First, I’d loose all the boosted EQ settings below the crossover frequency for both channels. That's the subwoofer's territory.


Thanks Wayne, I kind of did suspect there were to many filters and now you have explained your recommendatons I can see the error of my ways. I'll give it a bash over the weekend and see how it sounds.



Wayne A. Pflughaupt said:


> For your sub, I’d say it’s probably your placement that’s killing you. Will it fit in that corner behind the left speaker? Corner placement often works wonders in asymmetrical rooms like yours. It should boost your output and get you better extension, and any response anomalies will probably be easily equalizable (unlike with your current placement).


Yes I know the placement is not great, I have tried moving it a little but now into that corner due to space issues. I will have a look and see what can be done, at least now I have ditched the house curve I know what it should look like.

Here's to a weekend of fun!


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## brucek

> I’d say it’s probably your placement that’s killing you


I would get those mains out from being behind the TV and so close to the walls. At least make them equal or slightly in front of the rack and test... you'll be surprised in the new soundstage that you getting.

Yeah, put the sub in the corner (since you're going to move the speaker out, there will be room).

brucek


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## spreston

Hi Orange,

I tried to EQ full range with a Behringer DEQ2496. With one set of speakers, the effect was rather interesting and it was fun to fix the EQ work done by recording engineers. 

However, I found the output of the Behringer to be less than transparent (maybe the DAC, maybe other issues in the box). As a stand-alone DAC it works but I have heard better. In the end, I decided to run my mains directly from the poweramps. The sub is a different beast entirely.

You might have a different experience running your mains with your EQ and using different DACs.


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## Rudy81

I am following your post with interest since I have just recently made my first measurements. I am wondering why the roll off beyond 10kHz? I have a very similar plot and can't figure out why the tweeters roll off that way. Am I setting something incorrectly?

Thanks,
Rudy


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## sfdoddsy

Most in-room measurements from the listening position will show that kind of treble roll-off. I wouldn't worry about it.


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## Wayne A. Pflughaupt

Rudy81 said:


> I am following your post with interest since I have just recently made my first measurements. I am wondering why the roll off beyond 10kHz? I have a very similar plot and can't figure out why the tweeters roll off that way. Am I setting something incorrectly?


Most often, it’s the result of poor measurement technique – specifically, pointing the mic at the ceiling. The mic’s pick-up pattern is omnidirectional for most of the frequency range, but at the highest frequencies it becomes directional. So naturally, if you use a vertical orientation the only information it’s getting at the extreme frequencies is what’s bouncing off the ceiling – if that. 

Presumably, if you’re taking full-range measurements, you’re interested in seeing what response at the listening position is. You want a graph that shows both what your speaker are generating and what you’re hearing at that position. The best way to accomplish this is to set up the mic at the listening position and aim it at the speaker.

Regards,
Wayne


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## brucek

> The best way to accomplish this is to set up the mic at the listening position and aim it at the speaker.


The generic file that we provide from Cross Spectrum is frontal incidence. Certainly for near-field measurements the mic should be oriented horizontally and pointed at the speaker for accurate high frequency readings, but for listening position measurements with the downloadable cal file, to take advantage of direct and reflective signal, Cross Spectrum (and our download page advice) recommends to point the mic vertical with a 10-20 degree tilt toward the front of the room.

brucek


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## weverb

brucek said:


> The generic file that we provide from Cross Spectrum is frontal incidence. Certainly for near-field measurements the mic should be oriented horizontally and pointed at the speaker for accurate high frequency readings, but for listening position measurements with the downloadable cal file, to take advantage of direct and reflective signal, Cross Spectrum (and our download page advice) recommends to point the mic vertical with a 10-20 degree tilt toward the front of the room.
> 
> brucek


This is the technique I use, but I also had Cross Spectrum provide me calibration files for both orientations. :nerd::bigsmile:



Oh, and thanks to Wayne's great mentoring, I EQ full range. :innocent:


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## Wayne A. Pflughaupt

brucek said:


> The generic file that we provide from Cross Spectrum is [calibrated for] frontal incidence. Certainly... for listening position measurements with the downloadable cal file, to take advantage of direct and reflective signal, Cross Spectrum (and our download page advice) recommends to point the mic vertical with a 10-20 degree tilt toward the front of the room.


Yes, I know vertical is what Cross Spectrum recommends, but it’s poor technique in general and counter-intuitive in particular for a mic that’s calibrated for horizontal orientation. Not to mention, it’s contrary to long-accepted industry standards for in-room, full-range free field audio spectrum analysis: I’ve never seen any professional system calibration done utilizing a vertical mic, and I haven’t seen any manufacturer of hardware RTAs, nor any software program (such as TrueRTA), recommend it either (although admittedly I probably don’t know all of them that are available). Typically RTA manufacturers have specified and provided a different mic capsule if vertical-incident measurements were preferred.

Vertical orientation doesn’t “take advantage” of the direct signal at the extreme high frequencies - it minimizes them, due to the aforementioned high-freq directionality issue with the mic.

As far as reflective signals, for the life of me I don’t see why anyone would want to _insure_ that they they’re captured for a full-range measurement, since by all accounts they degrade the accuracy of a listening-position measurement. But below 6 kHz or so they’re all going to be there anyway with horizontal orientation, so nothing is _lost_, reflections-wise, by aiming the mic at the speaker, yet you _gain_ the advantage of seeing what your speakers are delivering above 6 kHz at the listening position.

weverb has the right idea – if vertical orientation is the desired method of measurement, the mic should be calibrated for it, to compensate for the natural high-end loss.

Regards,
Wayne


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## brucek

> I’ve never seen any professional system calibration done utilizing a vertical mic, and I haven’t seen any manufacturer of hardware RTAs, nor any software program (such as TrueRTA), recommend it either


Yeah, I'm certainly no expert on the subject. I only wrote what Cross Spectrum advised as a proper method to measure at the listening position. It isn't vertical, but vertical with a forward tilt of 10-20 degrees.

Perhaps we should change it, if you're convinced Cross Spectrum is wrong... :dontknow:

Cross Spectrum said: ......._I'm saying use an almost-vertical orientation where "vertical" is 90 degrees and I rotate the mic toward the floor by 10-20 degrees (if "vertical" is 12-o'clock, I measure with the mic pointing at ~1 or 2-o'clock). There will be some error since the cal file is based on an horizontal alignment, but even with the "correct" cal file there will be some error at the highest frequencies regardless because you're using a freefield mic for what is essentially a diffuse-field measurement._

That just seemed to make sense to me. We provide a frontal incident horizontal cal file for those that want the close speaker measurement, but when measuring a diffuse field, the mic is pointed toward the front of the room. I tend to use more like 20 degrees myself, but I tried to keep the recommendation on the download page closer to what Cross Spectrum advises. After all, it's their cal file measurement....

brucek


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## Sonnie

We also have to consider what Audyssey recommends for their calibrated mic... and SVS with the same mic. Also keep in mind that in a surround sound system you would be totally opposite of the rear speakers if you point it straight forward towards the front. It will depend a lot on what exactly you are measuring. For subs... it will not matter.

If you want to take measurements of a two-channel system, then pointing it towards the center of the two front speakers might be preferred, but only if you have the proper calibration file for that orientation.

Either way, provided the proper calibration file is used for the corresponding orientation, it won't make a hill of beans difference. 

Actually... I am not sure why we do not point it to the side one time and then to the other side the next time, then sum the two. Isn't that the direction our ears are pointed? :huh:


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## Kal Rubinson

Sonnie said:


> We also have to consider what Audyssey recommends for their calibrated mic... and SVS with the same mic. Also keep in mind that in a surround sound system you would be totally opposite of the rear speakers if you point it straight forward towards the front. It will depend a lot on what exactly you are measuring. For subs... it will not matter.
> 
> If you want to take measurements of a two-channel system, then pointing it towards the center of the two front speakers might be preferred, but only if you have the proper calibration file for that orientation.
> 
> Either way, provided the proper calibration file is used for the corresponding orientation, it won't make a hill of beans difference.


You raise a good point in that we are assured that the proper calibration file is in the equipment and also instructed to aim the mic vertically. OTOH, one of the things this assures is that the (sorta) omnidirectional mic favors none of the speakers. The downside is that the FR falls off at the high frequencies but one hopes/expects that the cal curve takes care of that.



> Actually... I am not sure why we do not point it to the side one time and then to the other side the next time, then sum the two. Isn't that the direction our ears are pointed? :huh:


Well, there's much more to the "aiming" than the angle. The shape of the pinna and the head also affects how we hear with each ear but you do not want to compensate for those things since they are what allow us to localize sounds. Compensate for them and localization becomes more difficult.


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## Wayne A. Pflughaupt

brucek said:


> _ …(if "vertical" is 12-o'clock, I measure with the mic pointing at ~1 or 2-o'clock). There will be some error since the cal file is based on an horizontal alignment, but even with the "correct" cal file there will be some error at the highest frequencies regardless because you're using a freefield mic for what is essentially a diffuse-field measurement. _


Sure - what they’re talking about there is essentially the same as what I noted, that in-room reflections are a know factor that’s going to influence, and skew to a certain extent, an in-room measurement. I don’t have a problem with that, because reflections are what you’re hearing at the listening position along with the direct signal. If that's what I'm hearing, then that's what I want to see measured. However...



> That just seemed to make sense to me. ... when measuring a diffuse field, the mic is pointed toward the front of the room [~1 or 2-o'clock].


 For starters, a typical home theater doesn’t qualify as a “diffuse field” in the strict definition of the term. A diffuse field is usually defined as one where the sound is arriving from all directions more or less simultaneously, with equal probability and level. In other words, an exceedingly reverberant environment. That just doesn’t describe the typical residential situation, unless perhaps one is living in a cinder-block house with no furnishings.

Aside from that - color me plumb stupid, but I’m at a loss to understand how vertical orientation makes sense, even with a slightly forward tilt. It’s a given that these mics are increasingly directional the higher the frequency range goes. Pointing it vertical without the benefit of vertical-orientation calibration (and 1-2 o’clock isn't far enough removed from straight-up to make a significant difference) – how can one expect to get anything but deficient high frequency information? :scratch: It’s beyond mere “error,” it’s a wholesale deprivation of the high end that results in a graph bearing no resemblance to what you’re actually hearing (or at least what your speakers are delivering  ) at the measurement location. 



> We provide a frontal incident horizontal cal file for those that want the close speaker measurement,


In-room measurement is a different animal from close-speaker measurement. But just because a 0-degree orientation is appropriate for close speaker measurement, that doesn’t mean it’s unsuitable in-room measurement.



> I tend to use more like 20 degrees myself...


Have you tried aiming the mic at the speaker? We’re getting lots of feedback from folks saying that when they tried that method (using our horizontal-incidence calibration file) they got a reading more along the lines of what they were expecting from their speakers. 



> Perhaps we should change it, if you're convinced Cross Spectrum is wrong...


Well, I think already we’ve seen enough people dismayed at their graphs with drooping high end to conclude that our current recommendations aren’t cutting it.

AFAIK, horizontal orientation, with perhaps a 10-20 degree upward tilt, has been the industry standard for in-room measurements since RTAs became readily available nearly 30 years ago. If that’s changed I’m unaware of it, but admittedly I am on the “sidelines” of that field these days. So when the issue first came up here on the Forum several months ago, I looked up the manuals for every manufactured hardware RTA I could find, even discontinued ones, and nothing I saw indicated that the industry has moved to vertical orientation of the calibrated mics they include with their hardware. Same with the few software programs I looked at. In fact, typically no mic orientation is mentioned at all – it’s as if they assume the user knows what to do. 

Here’s a picture from the manual of my mid-90s vintage AudioControl RTA:







​



> ... but I tried to keep the recommendation on the download page closer to what Cross Spectrum advises. After all, it's their cal file measurement....


 There are all kinds of acoustics-related fields and disciplines that would have a use for calibrated measurement mics: companies that design concert halls or recording studios and civil engineering firms that deal in highway noise abatement are a couple that come to mind. The automotive and aerospace industries have a keen interest in acoustics relating to cabin and interior noise levels, as does the Navy in ships. Then you have things like transducer manufacturers, design and manufacture of hearing aids, etc.

Presumably each field has determined the best way accomplish the measurements they need in order to achieve their specific objectives, and I doubt any mic calibration lab had a part in making those determinations. Wouldn’t that be a bit like the guy who fires the brick telling you how to build a house? :huh:

Regards,
Wayne


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## Wayne A. Pflughaupt

Sonnie said:


> We also have to consider what Audyssey recommends for their calibrated mic... and SVS with the same mic.


 I don’t see any pressing need for us to give quarter to Audyssey/SVS recommendations. Anyone using their equipment should follow their guidelines, which are wholly appropriate for their application: microprocessor-controlled tuning of a multi-speaker system. We’re primarily generating frequency response graphs (and others related to that), so our calibration files, as well as our recommendations for how to use them, is an entirely a different matter.



> Also keep in mind that in a surround sound system you would be totally opposite of the rear speakers if you point it straight forward towards the front.


You should point the mic towards the speaker you want to take a measurement of.



> If you want to take measurements of a two-channel system, then pointing it towards the center of the two front speakers might be preferred, but only if you have the proper calibration file for that orientation.


And as I understand it, horizontal orientation is the only generic file we offer...



> Either way, provided the proper calibration file is used for the corresponding orientation, it won't make a hill of beans difference.


Yup - the key is to use the mic in accordance to the proper calibration file. Comparing weverb’s graph (generated with a mic calibrated for vertical orientation), to the graphs with sagging high end from those folks using vertical orientation with a horizontal calibration file, should be evidence enough.

Regards,
Wayne


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## weverb

:meal: I am enjoying and learning from this good debate. Although, now I feel like I should go get a mic boom so I can "hang" the mic at the listening position with minimal interaction with the speaker response and compare the vertical to horizontal readings. :dumbcrazy:


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## Sonnie

Wayne A. Pflughaupt said:


> Yup - the key is to use the mic in accordance to the proper calibration file. Comparing weverb’s graph (generated with a mic calibrated for vertical orientation), to the graphs with sagging high end from those folks using vertical orientation with a horizontal calibration file, should be evidence enough.


I am not sure why anyone would be using vertical orientation with a horizontal calibration file. What am I missing? :scratch:

When someone goes to download our cal file the information is clearly stated in red:

They are all on-axis (facing the sound source - horizontal position) response measurement files.
Cross-Spectrum employs the pressure method to calibrate the low frequency response and the quasi-anechoic free-field on-axis method to calibrate the upper frequency response.

For listening position measurements we recommend that the meter or mic be oriented vertically with a forward angle of about 10 - 20 degrees to capture a good mix of direct and reflected sound for 'room' measurements. 

I am like brucek on this one... :dontknow:


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## Sonnie

Wayne A. Pflughaupt said:


> You should point the mic towards the speaker you want to take a measurement of.


If you are going to measure one speaker at a time, which is not going to do anyone any good unless they have the brain of Audyssey to calculate the proper settings for all their speakers. In most cases, I would think people would do sweeps of their entire system. That is what I do when I measure full range. I certainly ain't gonna measure the left speaker then right speaker independently and try to equalize them independently. Once you measure them together after equalizing them independently, the response is going to be all over the place because of the interaction of the two speakers. The picture you provide contradicts your suggestion... it is pointed to the center. Of course that may be what you mean... point in the general direction of the ones you want to measure. I am speaking of measuring from the listening position, not nearfield.

EDIT: Those are also poor instructions in that picture too. When you are listening are your ears 3' clear of everything surrounding them. Those instructions are not real world and are not what you will actually hear. The mic needs to be very near where your ears will be. If there is reflection or absorption from a chair, then your measurement needs to take that into account and you need to equalize for it. This is one reason I have always been the proponent of placing the mic at my ear when measuring... but at least placing it where your ears will be... not out in the middle of the room where it will sound completely different than where you sit.


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## brucek

> I’m at a loss to understand how it makes sense. It’s a given that these mics are increasingly directional the higher the frequency range goes. Pointing it vertical without the benefit of vertical-orientation calibration (and 1-2 o’clock isn't far enough removed from straight-up to make a significant difference) – how can one expect to get anything but deficient high frequency information? It’s beyond mere “error,” it’s a wholesale deprivation of the high end that results in a graph bearing no resemblance to what you’re actually hearing (or at least what your speakers are delivering ) at the measurement location.


Yeah, you certainly make some good points Wayne. I'm somewhat on the fence, but I think this is the key point. What a single speaker delivers, and what is present at a listening position when two main speakers are playing is quite different. The listening position is the result of direct and reflected sound. That direct sound is affected by both the mixing and axis of two speakers, and the reflected sound is a result of the room. The reflections come from everywhere, including quite a bit from the rear. A horizontal mic positioning will basically ignore those signals. I do think we want to favour the direct sound and so the mic is tilted in that direction (albeit only slightly), such that we favour the direct, but don't ignore the reflected.

The direct sound will also be altered by the off-axis placement of each main. If the speakers are facing directly forward rather than toed-in (as many people like the increased soundstage it offers), there can be many degrees of off-axis to deal with, so even a horizontal mic placed between the two speakers is problematic.

I did some tests a while back on my mains and measured horizontal mic placement at 50" at 0 degrees on-axis compared against a horizontal mic placement using 30 degrees off-axis. Both tests were with the mic pointing directly at the speaker. The result is shown below, where even a small off-axis angle kills the high frequencies.








.

I show this to reinforce the statement that the only way to see "_what your speakers are delivering_" is to do a near field measure with the mic horizontal and on axis at zero degrees. Anything else is not going to be accurate. 

I suppose there's merit in recommending a vertical mic position with a vertical calibration file, but my feeling is that should be left for those that want to get their own mics calibrated with two files, one for vertical and one for horizontal. We all agree that the generic file isn't accurate regardless of the mics orientation, so to supply two different files for mic orientation in a generic form seems a bit silly to me. I think we make it clear that for proper HF readings of a speaker users should measure a speaker near field.

brucek


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## Wayne A. Pflughaupt

Sonnie said:


> I am not sure why anyone would be using vertical orientation with a horizontal calibration file. What am I missing? :scratch:
> When someone goes to download our cal file the information is clearly stated in red:
> 
> They are all on-axis (facing the sound source - horizontal position) response measurement files.
> Cross-Spectrum employs the pressure method to calibrate the low frequency response and the quasi-anechoic free-field on-axis method to calibrate the upper frequency response.
> 
> For listening position measurements we recommend that the meter or mic be oriented vertically with a forward angle of about 10 - 20 degrees to capture a good mix of direct and reflected sound for 'room' measurements.


Basically, for the purposes of measuring frequency response, acoustical spaces fall into two categories: diffuse field or free field. 

Free field essentially means an open space, free of reflections. According to the protocol recommended by most manufacturers of measurement mics, free-field measurements should be performed with the mic pointed directly at the sound source, and angled 20-degrees upward. 

A diffuse field (aka random incident) environment is one where the sound is arriving from all directions more or less simultaneously, with equal probability and level. In other words, an exceedingly reverberant environment. Diffuse field measurements are typically accomplished with the mic angled at approximately 70-80 degrees, oriented towards the sound source. 

Actually, very few venues are so reverberant that they would qualify as textbook diffuse field, even if they have bad acoustics. So the question is, is the typical home theater more akin to a free field or diffuse field environment? They typically have reflections, but aren’t exactly a highly-reverberant environment (unless perhaps someone is living in a cinderblock house). I’d characterize them as being closer to a free field environment than diffuse field – much closer. Therefore the best way to measure a home theater is to use the free field protocol when taking full range measurements. Subwoofers are different, of course. Bass frequencies could be classified as diffuse field, since they meet the requirement of "arriving from all directions, with equal probability and level." 




Sonnie said:


> If you are going to measure one speaker at a time, which is not going to do anyone any good unless they have the brain of Audyssey to calculate the proper settings for all their speakers. In most cases, I would think people would do sweeps of their entire system. That is what I do when I measure full range.


The only reason to measure any speaker independently would be if you intend to equalize it specifically, or if you just want to see what its response is. Not sure how you do a sweep of the entire system, since REW can only be plugged into the two front speakers? :scratch: I wouldn’t do that anyway, because all the soundwaves bouncing around from so many speakers (including the room reflections) isn’t going to give a meaningful reading. It would only be a “just for grins” thing – you certainly wouldn’t want to make any system adjustments based on an “all speakers running” reading (except perhaps a sub level adjustment). Generally, RTA should be done one speaker at a time, or perhaps a speaker w/ subs.




> I certainly ain't gonna measure the left speaker then right speaker independently and try to equalize them independently. Once you measure them together after equalizing them independently, the response is going to be all over the place because of the interaction of the two speakers.


That may happen with multiple subs, but it’s not the case with mains at all. There is a proper procedure for measuring and equalizing speakers independently, but that's a thread for another day. 




> The picture you provide contradicts your suggestion... [the mic] is pointed to the center.


Hmmm… Looks to me like it's off-center, pointed at the left speaker...




> EDIT: Those are also poor instructions in that picture too. When you are listening are your ears 3' clear of everything surrounding them. Those instructions are not real world and are not what you will actually hear. The mic needs to be very near where your ears will be.


It’s generally accepted that mics don’t “hear” the same way we do. Reflections from near-by objects that our ears can readily ignore can have a negative effect on what the mic sends to the RTA, which can skew the reading to show something that you really aren’t hearing. It isn’t necessary to get the mic _precisely_ where your ears are. No one expects in-room measurements to deliver laboratory-grade results. A few feet in front of where your head would be would deliver a perfectly acceptable (and useful) reading. 

Regards,
Wayne


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## Sonnie

Wayne A. Pflughaupt said:


> The only reason to measure any speaker independently would be if you intend to equalize it specifically, or if you just want to see what its response is.


Right... which not many of us are doing when we try to equalize our rooms.



Wayne A. Pflughaupt said:


> Not sure how you do a sweep of the entire system, since REW can only be plugged into the two front speakers? :scratch:


What do you mean it can only be plugged into the two front speakers??? Yeah... definitely scratching my head on that one. I plug REW into the front inputs of my receiver and run the sweep through all of my speakers for my measurements. I want to know what my ears are hearing and they hear all of the speakers, not one at a time or just the two front ones.




Wayne A. Pflughaupt said:


> I wouldn’t do that anyway, because all the soundwaves bouncing around from so many speakers (including the room reflections) isn’t going to give a meaningful reading. It would only be a “just for grins” thing – you certainly wouldn’t want to make any system adjustments based on an “all speakers running” reading (except perhaps a sub level adjustment). Generally, RTA should be done one speaker at a time, or perhaps a speaker w/ subs.


As noted above, I want to know what my ears are hearing and they do not hear just one speaker at a time... they hear all of them together. I am not sure why equalizing a 30Hz tone would be any different than equalizing a 3KHz tone... the ultimate goal is to get it flat. If we do not take into consideration how those reflections will effect it, then it definitely is not going to be accurate.




Wayne A. Pflughaupt said:


> That may happen with multiple subs, but it’s not the case with mains at all.


I think you would be surprised if you tried it sometime. If I measure just one speaker at a time, it may not show that peak at 2KHz that is there with all speakers measured together. Again... I do not have the brain of Audyssey to know how those speakers are going to interact... and that actually may be why Audyssey doesn't always get it right either. It usually gets the subs right because it is measuring and equalizing them all at one time, but struggles with the mid and upper end because it is measuring them one at a time. 

I can go out in my room right now and measure a full band sweep of all speakers and manually fix a peak that Audyssey missed, provided I am willing to give up all else that Audyssey did. I highly doubt anyone else can do that by measuring one speaker at a time.


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## DrWho

Orange55 said:


> But am I doing something which should be avoided?


Don't use any smoothing, and you should be time-gating your impulse so that you don't EQ frequency aberrations caused by reflections. Since we hear in the time-domain, we don't hear the tonal shift that you might measure if you don't gate the impulse....instead, we hear it as a separate reflection. Adding EQ will then screw up the tonal balance of the direct sound that we perceive as separate from the reflection.

The only catch to this is that you lose frequency resolution the shorter you gate....REW will tell you what the resolution is and doesn't draw the line below that frequency since it wouldn't make any sense.


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## Wayne A. Pflughaupt

> ---Quote (Originally by Wayne A. Pflughaupt)---
> Not sure how you do a sweep of the entire system, since REW can only be plugged into the two front speakers? :scratch:
> 
> 
> 
> What do you mean it can only be plugged into the two front speakers??? Yeah... definitely scratching my head on that one. I plug REW into the front inputs of my receiver and run the sweep through all of my speakers for my measurements.
Click to expand...

Hey, I was merely quoting a highly reliable source!  You must have one of those nifty 5-channel stereo modes or something like that. My ancient gear doesn’t have such luxuries. 




> ---Quote (Originally by Wayne A. Pflughaupt)---
> I wouldn't do that anyway, because all the soundwaves bouncing around from so many speakers (including the room reflections) isn't going to give a meaningful reading. It would only be a "just for grins" thing - you certainly wouldn't want to make any system adjustments based on an "all speakers running" reading (except perhaps a sub level adjustment). Generally, RTA should be done one speaker at a time, or perhaps a speaker w/ subs.
> 
> 
> 
> As noted above, I want to know what my ears are hearing and they do not hear just one speaker at a time... they hear all of them together. I am not sure why equalizing a 30Hz tone would be any different than equalizing a 3KHz tone... the ultimate goal is to get it flat. If we do not take into consideration how those reflections will effect it, then it definitely is not going to be accurate.
Click to expand...

 Sure, it’ll get you a nice “FYI” graph that tells you what your ears are hearing with the full system going. But there’s no way you’d ever get anything resembling accuracy trying to manually equalize this way. For instance, if the graph shows a problem at a certain frequency, how will you determine which speaker(s) it is coming from if all are playing at the same time? Especially if you have an asymmetrical room like mine, with some speakers closer to boundaries than others.




> ---Quote (Originally by Wayne A. Pflughaupt)---
> That may happen with multiple subs, but it's not the case with mains at all.
> 
> 
> 
> I think you would be surprised if you tried it sometime.
Click to expand...

I have. It works fine - been doing it well over 10 years now. (As long as we’re talking about bass-managed speakers, of course.) Each of my speakers is independently equalized, the front three with parametric, the back two a bit less-precisely with my receiver’s on-board quasi-parametric EQ. My ears and RTA confirm that response is not trashed when they are all operating together.




> If I measure just one speaker at a time, it may not show that peak at 2KHz that is there with all speakers measured together.


Trust me, something like that would never “just happen.” Independent measuring would identify the speaker(s) with the offending problem. 

Regards,
Wayne


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## Wayne A. Pflughaupt

brucek said:


> What a single speaker delivers, and what is present at a listening position when two main speakers are playing is quite different. The listening position is the result of direct and reflected sound. That direct sound is affected by both the mixing and axis of two speakers, and the reflected sound is a result of the room. The reflections come from everywhere, including quite a bit from the rear. A horizontal mic positioning will basically ignore those signals.


 The mic will only ignore the upper frequencies – it’s omnidirectional. You’ll still get plenty of side and rear reflection information.

Furthermore, I’d submit that side- and (especially) rear-reflections, are high-frequency deficient to begin with, due to dispersion and absorption from the various surfaces (unless you have glass walls or something like that!). This is why someone can bring you into your room blindfolded, spin you around, and you can easily point to where the sound is originating from. So IMO you’re losing little in the way of meaningful reflections measuring with horizontal mic orientation.

But as Dr. Who noted in this post you should orient the mic so that it captures the information you’re looking for. If you want to ensure you’re getting all the reflections, then by all means position the mic vertically. Just keep in mind that it might affect the accuracy of your high-frequency measurements.




> The direct sound will also be altered by the off-axis placement of each main. If the speakers are facing directly forward rather than toed-in (as many people like the increased soundstage it offers), there can be many degrees of off-axis to deal with, so even a horizontal mic placed between the two speakers is problematic.
> 
> I did some tests a while back on my mains and measured horizontal mic placement at 50" at 0 degrees on-axis compared against a horizontal mic placement using 30 degrees off-axis. Both tests were with the mic pointing directly at the speaker. The result is shown below, where even a small off-axis angle kills the high frequencies.
> 
> 
> 
> 
> 
> 
> 
> 
> I show this to reinforce the statement that the only way to see "what your speakers are delivering" is to do a near field measure with the mic horizontal and on axis at zero degrees. Anything else is not going to be accurate.


 I can’t quite agree with your assessment. If orienting the speaker off axis delivers an inaccurate picture of the speaker’s response, then how can orienting a measurement mic severely off axis _do anything but the same thing?_ Sure, “the direct sound will be altered by off-axis placement” of the mains. And a measurement mic. 

In reality both graphs are accurate. Both show the high freq content that is reaching the listening position (assuming that’s where the measurement was taken?) with two different speaker orientations. Determining optimal speaker placement and positioning – isn’t that one of the reasons we take these measurements to begin with? I would assume that you can probably hear the difference between the two speaker placements, and I'll bet the way it sounds closely resembles what you measured. (Side note: If someone likes the off-axis imaging, but not the high frequency loss, the graph would show how to EQ to make up for it.)

I think your experiment actually helps prove my point, because consider this: If you had taken those two readings with the mic in a vertical position, _most likely they would have looked the same_. The reason? Even with vertical orientation of the mic using the proper vertical-incident correction file, the file makes up for the loss of high frequency _information_, but the file can’t reclaim the benefit of the mic’s high-frequency _directivity_. 

IOW, I expect that vertical orientation would not readily register a change in frequency response when you toe the speakers away from or towards the listening position. 




> I show this to reinforce the statement that the only way to see "_what your speakers are delivering_" is to do a near field measure with the mic horizontal and on axis at zero degrees. Anything else is not going to be accurate.


A near-field measurement does _not_ represent what is heard at the listening position (assuming the listening position is not near-field), and I expect it would be problematic to find a professional who would agree with or practice near-field when tuning a system. 

If I may be so bold as to make a recommendation to you and Sonnie - why not do what I do when I’m trying to decide what the correct approach is: consult a pro! 

Regards,
Wayne


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## Sonnie

Wayne A. Pflughaupt said:


> Sure, it’ll get you a nice “FYI” graph that tells you what your ears are hearing with the full system going. But there’s no way you’d ever get anything resembling accuracy trying to manually equalize this way. For instance, if the graph shows a problem at a certain frequency, how will you determine which speaker(s) it is coming from if all are playing at the same time? Especially if you have an asymmetrical room like mine, with some speakers closer to boundaries than others.
> 
> 
> I have. It works fine - been doing it well over 10 years now. (As long as we’re talking about bass-managed speakers, of course.) Each of my speakers is independently equalized, the front three with parametric, the back two a bit less-precisely with my receiver’s on-board quasi-parametric EQ. My ears and RTA confirm that response is not trashed when they are all operating together.
> 
> 
> Trust me, something like that would never “just happen.” Independent measuring would identify the speaker(s) with the offending problem.


As previously eluded to... I can have a peak at 2KHz from measuring all speakers at once and easily cure it, just like I do with my subs. There is no way I could identify which speaker it is coming from if I tried to measure only one speaker at a time simply because it would not show up. It only shows because of the combination of speakers. I am not sure why this is so hard to understand. Unless you actually try it, you will never know. 

When you have that 2KHz peak with the combined speakers measured, you do not need to know what speaker is causing the problem. Simply reduce 2KHz a little and remeasure... it will be reduced. It is no different than the way we equalize multiple subs. I promise... try it sometime. :T




Wayne A. Pflughaupt said:


> If I may be so bold as to make a recommendation to you and Sonnie - why not do what I do when I’m trying to decide what the correct approach is: consult a pro!


For what I am referring to... no pro is needed... it is so very simple and it works fine.


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## Sonnie

I did not realize my NAD did not have manual EQ like my previous Onkyo did. I just went out to the HT room and was gonna prove my point. But unfortunately I can't at this time. Hmmm! Oh well... as soon as I upgrade the boards I should have the manual EQ then. I will post a before and after all speaker measurement of what I am referring to. Of course, I have done this several times from 20-80Hz, but I want to show it to you at somewhere between 500-4000Hz. I will refrain from any more comments until then. Sometimes a picture is worth a thousand words.


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## weverb

Gentlemen,

I am enjoying and learning from this good discussion. Thank you all for sharing.

I have just a minor thing I would like to add. Sorry if it is off topic! :hide: Not to take sides, but one thing that benefited me in my short time evaluating my system, is looking at each speaker on an individual basis. When I look at both my mains I get the following ETC graph :



If it was not for measuring each speaker by itself, I would have never known the offending spike/reflection was from the right speaker (yellow) and not the left (green). 



Now I wish it was just as easy to figure out what is causing the reflection. That is proving harder than I thought.

Please resume your discussion so that I may continue to learn. :hail:


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## brucek

> I wish it was just as easy to figure out what is causing the reflection. That is proving harder than I thought.


Not too difficult.

Expand the horizontal scale and use the measurment tool to readout the distance in feet.

The distance is how much further the signal had to travel before it reached the mic.

So, if it is 2 feet, then the reflection could be a wall exactly a foot directly behind the mic, or it may be a sidewall reflection that adds the extra distance. Move the mic a bit, remeasure and figure out where the reflection moves to and it is fairly easy to figure out.

The measurement tool is selected by holding down Ctrl + Shift and use the right mouse button to drag from the main bang to the reflection. See below: In this case the signal had to travel and extra 2.5 feet.









brucek


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## weverb

Hey brucek,

You have shown me that before. The measurement I get is like just a few inches. I have tried placing an absorbent panel all around the speaker and mic (actaully a thicker one behind it) and still cannot seem to get the spike to reduce. :huh: I will keep trying different things. Question though. Since the spike is almost equal to the original signal, could it cause an error or false dimension?


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## Sonnie

No sides here weverb... we are all on the same team. Please keep in mind that I never stated NOT to measure each speaker individually. The point I am making is that if you want to measure all speakers at once, which is completely feasible to do in many cases, then pointing the mic directly towards one speaker will not give you the best measurements. I had to go around the block to make that point. When it comes to identifying the technical anomalies that you are trying to identify, then it may indeed require individual measurements. I would suggest though that not many will go to this much detail with their measurements.


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## weverb

Sonnie said:


> No sides here weverb... we are all on the same team. Please keep in mind that I never stated NOT to measure each speaker individually. The point I am making is that if you want to measure all speakers at once, which is completely feasible to do in many cases, then pointing the mic directly towards one speaker will not give you the best measurements. I had to go around the block to make that point. When it comes to identifying the technical anomalies that you are trying to identify, then it may indeed require individual measurements. I would suggest though that not many will go to this much detail with their measurements.


:T Gotcha. Can I make another observation.....:hide:... keep in mind this pertains to my unique set-up/room. 

When I first started down the road of full range eq, I would measure and eq both main speakers together. This would result in a good looking graph all the time. I was happy and things sounded pretty good. Since then, I have learned more through HTS and the great people on here. You have given me confidence to try new things with the knowledge I gained. From there I started looking at each of the 5 non-sub speakers in my set-up. What I start to notice, when listening to 2-channel music mostly (but this will also apply to HT too), that there were sometimes noticeable differences between the mains. It was mostly evident when things would pan back and forth from left to right. Floyd, Dire Straights, and some jazz were good tests for this. When I started measuring individual mains, I found some areas that were very different and required different filters. Say for example, the left would be too high in the range of 1k-4k Hz. while the right may be a little low. Combined, the graph would balance out and look good. When they played together, things in the center stage would sound great. When things would pan to one side or the other, you could hear the difference.

To summarize, I can see both sides here. I can see where Sonnie's example applies, but I can also agree with Wayne from past experience. I find that I get the best results from doing both techniques. I know that means a lot of time and measuring, but I have been enjoying the journey by learning and hearing my set-up improve. This may not apply to everyone. But then again, full range eq is not for everyone. Maybe we should sticky this thread with others that show the true journey/requirements to get good results when one heads down this path. :huh:

I will shut up now and let the more experienced and knowledgable teach me more. :hail:

:heehee:


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## Wayne A. Pflughaupt

Sonnie said:


> I can have a peak at 2KHz from measuring all speakers at once and easily cure it, just like I do with my subs. There is no way I could identify which speaker it is coming from if I tried to measure only one speaker at a time simply because it would not show up. It only shows because of the combination of speakers. I am not sure why this is so hard to understand.


It’s not hard to understand, it’s just not a realistic scenario. All I’m saying is that if each of your speakers has linear response, whether naturally or via equalization, _you aren’t going to have some peak appear once you operate them all at the same time_. Ain’t gonna happen. Trust me, I’ve been doing this for a while!




> When you have that 2KHz peak with the combined speakers measured, you do not need to know what speaker is causing the problem. Simply reduce 2KHz a little and remeasure... it will be reduced. It is no different than the way we equalize multiple subs. I promise... try it sometime


 Sure, dialing down that 2 kHz problem will eliminate the peak and get a pretty graph, but _it is exceedingly poor technique to wipe out response from all non-offending speakers in order to address a problem caused by one_. Don’t take my word for it; any professional installer or system designer will tell you the same thing. 

Equalizing the main speakers is absolutely in no way like equalizing multiple subwoofers, because the main channels don’t function as a single entity the way the subs do. Each main channel is discrete. 

This would be especially relevant for home theater. For instance, if some movie has a sound effect rich in 2 kHz content, sent to the speaker or speakers that have had that range attenuated - obviously the level of the effect will be reduced, its timbre compromised, etc. Or, if the effect is panned around to all the speakers, it’s going to be louder in some than in others. Certainly, this is not a desirable outcome.

Here’s another scenario that’s perhaps a bit more relevant: What about us poor schmucks who have our center channel speaker stranded in an entertainment center? Mine has a honkin’ 9 dB peak at ~200 Hz that’s caused by the cabinet. Naturally, that would show up with an all-channels reading. Applying global EQ to pretty-up the graph and eliminate a peak caused by the center channel would leave a big hole in the upper bass when I switched gears to do some listening to music, would it not?




> I will refrain from any more comments until then. Sometimes a picture is worth a thousand words.


Cool, I love pictures!  Not that it’s necessary – I’m have no doubt that it’s possible to eliminate a peak that’s apparent with all channels operating by applying a global EQ adjustment.




> The point I am making is that if you want to measure all speakers at once, which is completely feasible to do in many cases, then pointing the mic directly towards one speaker will not give you the best measurements. I had to go around the block to make that point.


 _That’s_ what you’ve been tying to say? Why didn’t you just say so? :laugh: Well sure, you wouldn’t want to point the mic at a particular speaker in that situation. :T




> I would suggest though that not many will go to this much detail with their measurements.


 Certainly, no argument there! Few people have the patience, wherewithal and/or knowledge necessary to accomplish independent-channel equalization. And getting back to something you said earlier...


> I can go out in my room right now and measure a full band sweep of all speakers and manually fix a peak that Audyssey missed, provided I am willing to give up all else that Audyssey did. I highly doubt anyone else can do that by measuring one speaker at a time.


I think the writing’s on the wall: Audyssey and similar auto-equalizing technologies are going to render outboard equalization moot for all practical purposes, once it trickles down to lower-end receivers.

Regards,
Wayne


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## Wayne A. Pflughaupt

weverb said:


> Say for example, the left would be too high in the range of 1k-4k Hz. while the right may be a little low. Combined, the graph would balance out and look good. When they played together, things in the center stage would sound great.


Wow, that worked out okay for you? I had trouble with the soundstage getting whacked when I tried separate-channel EQing above about 400 Hz. But then again, that was back when I was using 1/3-octave equalizers. Looks like parametric precision makes a big difference. I never cease to be amazed at what these equalizers can do...

Regards,
Wayne


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## brucek

Sonnie said:


> When you have that 2KHz peak with the combined speakers measured, you do not need to know what speaker is causing the problem. Simply reduce 2KHz a little and remeasure... it will be reduced. It is no different than the way we equalize multiple subs.


Yeah, I'll have to agree with Wayne on this on.....it's way different trying to EQ all your mains speakers than it is multiple subs. Simply by the nature of the signal that the subs receive always being mono.

I have no doubts that when you place your center/fronts/rears/backs in a mono mode with the receiver, it's quite simple to EQ them all at the same time. This is the same as EQ'ing all your subs at once - no problem there.

The problem (as Wayne points out) is that the center/fronts/rears/backs don't receive a mono signal under normal playing conditions. They receive individual channel signals. Your single EQ may have caused an obscene result at the listening position from any single speaker to have accomplished the smooth response for all the speakers playing a mono signal in concert. That's OK with multiple subs, since they always receive the same mono signal.

Maybe after you EQ with your 'All CH' method, take a reading of each speaker and see if any are particularly bad. If so, then whenever that speaker is playing a sound by itself, that's the poor response you'll hear from it. :hush:

I feel the best way would be to EQ each speaker individually and then see what the result is when played in concert. If there's some touch up, then OK.


brucek


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## Sonnie

Wayne A. Pflughaupt said:


> It’s not hard to understand, it’s just not a realistic scenario. All I’m saying is that if each of your speakers has linear response, whether naturally or via equalization, _you aren’t going to have some peak appear once you operate them all at the same time_. Ain’t gonna happen. Trust me, I’ve been doing this for a while!


What? :blink: In a perfect world maybe, but we are far from that. It is not an issue of trust, it is an issue of fact. (No disrespect :bigsmile Absolutely without any doubt at all it will happen! I can prove it in your own home if I were there. I don't care if you have been doing it for umpteen dozen years... it will and does happen in nearly every situation. All speakers pretty much have linear response when you buy them... naturally. That is what the manufacturer aims for. If your statement were true we would have no need for equalization. :whistling: Whether the response for each speaker is linear at nearfield or from the listening position makes no difference... there are nearly always going to be peaks and dips when the sum of all speakers is measured. What do think Audyssey is doing? They are measuring and equalizing each speaker, but despite this they cannot rid all the peaks and valleys even from one position.



brucek said:


> The problem (as Wayne points out) is that the center/fronts/rears/backs don't receive a mono signal under normal playing conditions. They receive individual channel signals. Your single EQ may have caused an obscene result at the listening position from any single speaker to have accomplished the smooth response for all the speakers playing a mono signal in concert.


Would/could this not be half a dozen to one and six to another? Are there not many cases where the same frequencies play from both front speakers? I might even suggest more so than not in movies with music where the producer just sticks the music in all channels or both front channels.


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## tonyvdb

Is it not the point of adding some sort of EQ to the speakers to make them "sound" flat at the listening position? Speakers will never sound the same as they do in the home or audio store listening room as were intended to due to placement and room acoustics Audyssey can only correct so much so we are left with doing nothing and living with it or getting a good quality 1/3 octave EQ or something like the digital EQs we are seeing available. They can be your best friend or can make things worse if you boost or cut way to much but if used properly can do wonders to how a system sounds.


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## Wayne A. Pflughaupt

Sonnie said:


> I don't care if you have been doing it for umpteen dozen years... it will and does happen in nearly every situation.


Well, I'd like to think I learned a thing or two when I used to do this kind of stuff for a living. :huh: If this were truly the case, don't you think I would have seen it at least once in umteen dozen years? Aside from your HT and car systems, how many rooms have you measured and calibrated and set up systems in? :scratch: I have a feeling somehow we're not on the same page here...




> Would/could this not be half a dozen to one and six to another? Are there not many cases where the same frequencies play from both front speakers? I might even suggest more so than not in movies with music where the producer just sticks the music in all channels or both front channels.


Certainly, which is why you never, never equalize a system using program material: There is no consistency from one to the next.




> Whether the response for each speaker is linear at nearfield or from the listening position makes no difference... there are nearly always going to be peaks and dips when the sum of all speakers is measured.


Any new peaks or dips that may appear when all speakers are fired up is merely comb filtering. Comb filtering can be ignored, since it’s not really audible. The measurement mic doesn’t “hear” the way our ears do; that accounts for response being more “ragged” once all speakers are operating. However, this does not mean that it’s not a worthwhile goal to evaluate each speaker separately and equalize it as needed. That can only result in improved overall performance.

Regards,
Wayne


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## Wayne A. Pflughaupt

tonyvdb said:


> Is it not the point of adding some sort of EQ to the speakers to make them "sound" flat at the listening position?


Well, my thinking has always been that the idea of EQing the mains is to merely _improve_ response (assuming there is a problem, of course), not try to eliminate ever little ripple to get a picture-perfect graph. Typically that merely involves identifying (using something like REW) the problems that are “big enough” to be audible, like we did at this thread. Here one or our Members applied a few filters – nothing severe - and got an audible improvement (Post #11 shows the filters), even though the “After EQ” graph is anything but “perfect.”










Before EQ









After EQ​

Regards,
Wayne


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## Sonnie

Wayne A. Pflughaupt said:


> If this were truly the case, don't you think I would have seen it at least once in umteen dozen years? :scratch: I have a feeling somehow we're not on the same page here...


Somehow we must not be on the same page, because there is no doubt that just because you have all speakers with linear response does not mean you can forget about peaks. First of all... I have never seen or heard of anyone having a linear response in all speakers in an HT room from the listening position... so I am in dismay at how anyone would be able to prove it to begin with. I am hoping you simply miss-worded what you intended to say. :huh:



Wayne A. Pflughaupt said:


> Certainly, which is why you never, never equalize a system using program material: There is no consistency from one to the next.


And no one has suggested you do so... but you certainly equalize based on what you listen to the most. If it is movies and satellite TV, then it is mostly the same music material coming from the front mains, even many times all speakers. I was paying very close attention last night to the satellite TV. Every time... not just once or twice, but every time I heard music, it played from all five speakers... otherwise it was dialog from the center. Same thing with a movie I watched, Race to Witch Mountain... when music played... the same music was playing from all speakers. The only time there were instances of something coming from one speaker individually was when there was a pan of some sort... or very subtle noises from time to time.

Maybe regular music is different, depending on what you are listening to I suppose... because even on a lot of music I listen to, especially modern day stuff, the same music is coming from the front left and right speaker (in my car). Now when I go back and listen some of the older Pink Floyd stuff... something different is coming out of every speaker (exaggerating, but you can probably imagine). Even on the beginning of David Gilmour in Concert... both front speakers are playing his acoustic guitar... not just one.


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## Wayne A. Pflughaupt

Sonnie said:


> Somehow we must not be on the same page, because there is no doubt that just because you have all speakers with linear response does not mean you can forget about peaks.
> I am hoping you simply miss-worded what you intended to say. :huh:


I didn’t mis-word it. In taking a measurement of all the main channels (i.e., above the sub frequencies) running at the same time, you aren’t going get any “new” peaks in response that couldn’t be traced to one specific speaker. The upper frequencies don’t behave like the bass frequencies, it’s as simple as that.


Hey brucek, did you notice Terry’s thread where he utilized both near field and listening position measurements? If I understood correctly, he used the near field to verify that he wasn’t loosing his mind, something definitely was wrong at the listening position that shouldn’t be there. So it looks like near field can be useful to people even if they aren’t custom speaker builders; it just requires an imagination. :laugh:

Regards,
Wayne


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## brucek

> Hey brucek, did you notice Terry’s thread where he utilized both near field and listening position measurements?


Yeah, interesting. I have never had the opportunity to do full range EQ until I got my new Denon receiver this month for my back room office system. I guess that's why I have found this discussion particularly interesting. I also have the ability with that receiver to do an All Channel EQ or individual channel EQ full range, so it's a timely thread.

I think your center channel example is perfect to demonstrate how All channel EQ can be a big problem, especially for those that have bad rooms with wild swings in response. As you pointed out, if you have a huge 200Hz peak in a center channel speaker only and it results in someone doing an All channel EQ to reduce the resultant all channel peak at 200Hz, they will have a nice center channel, but all the other speakers will have a big dip at 200Hz.

EQ'ing each speaker by itself would be a pain though. Most receivers don't have the feature to play one speaker at a time, so you'd have to plug and unplug speakers to pull it off. 

Probably easier just to let Audyssey do it for you....

brucek


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## DrWho

tonyvdb said:


> Is it not the point of adding some sort of EQ to the speakers to make them "sound" flat at the listening position? Speakers will never sound the same as they do in the home or audio store listening room as were intended to due to placement and room acoustics Audyssey can only correct so much so we are left with doing nothing and living with it or getting a good quality 1/3 octave EQ or something like the digital EQs we are seeing available. They can be your best friend or can make things worse if you boost or cut way to much but if used properly can do wonders to how a system sounds.


Not to pick on anyone, but that kind of logic is precisely why there are so many bad sounding systems in the world. The reason the same speaker can sound both good and bad depending on the room has nothing to do with the quality of the signal going to the speaker. The room itself is changing the sound that comes out of the speaker, and to many extents has a sound all its own. How does an equalizer before the speaker change the influence of the room?

Sure, the world is always full of compromises (thus the reminder in my signature), but I've gotten to the point in my professional career where I don't even bother trying to do any EQ for room related issues. I delineate between issues and considerations because there are some things specific to rooms that should be dealt with in EQ, but it's just gonna confuse the point. If you truly want a great sounding system, then you must have a room with good acoustics. Bad acoustics just lends itself to tweaks that are more different than they are unmistakeable improvements....although I suppose there is something to be said for satisfying the paranoya of the audiophile  If you really want to see a flat line, then just zoom out on the y-axis of your plots.

There is a big difference between striving for a pretty line versus learning why your system sounds the way it does.

If your car had a flat tire, would it make sense to bend the axle so that it didn't feel bumpy anymore?

Sorry for venting...I'll let you guys get back to your microphone directivity discussions. But for what it's worth, mics are usually calibrated on-axis and then have polar response information from which the power response can be derived.


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## tonyvdb

DrWho said:


> Not to pick on anyone, but that kind of logic is precisely why there are so many bad sounding systems in the world. The reason the same speaker can sound both good and bad depending on the room has nothing to do with the quality of the signal going to the speaker. The room itself is changing the sound that comes out of the speaker, and to many extents has a sound all its own. How does an equalizer before the speaker change the influence of the room?


Even the best recording studios/auditoriums and concerts use equalizers between the board and the speakers to ensure the sound is output flat. If you choose to go without thats your choice however its not a general consensus.


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## tpaxadpom

Wayne A. Pflughaupt said:


> It’s not hard to understand, it’s just not a realistic scenario. All I’m saying is that if each of your speakers has linear response, whether naturally or via equalization, _you aren’t going to have some peak appear once you operate them all at the same time_. Ain’t gonna happen. Trust me, I’ve been doing this for a while!


Wayne, it is possible. Just imagine having 2 front speakers out of phase. Never done that? :neener:
Remember the school physics constructive and destructive interference? Speakers in the room will never be in the perfect phase due to placement, toe in, room interactions (not symmetrical) imho...
I think the ideal case is to EQ each of the speakers individually and then do low end touch up for all at the same time.


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## DrWho

tonyvdb said:


> Even the best recording studios/auditoriums and concerts use equalizers between the board and the speakers to ensure the sound is output flat. If you choose to go without thats your choice however its not a general consensus.


So how many of these studios/auditoriums have you measured personally?

Good venues simply do not have anywhere near a flat frequency response _when measured in the manner being described here_. In fact, I would encourage anyone to make a system measure flat with REW in its default windowing settings, and then compare what it sounds like against a system tweaked with modern EQ'ing methods. The difference is not small.

Anyone that wants to learn more can go take a course over at Syn-Aud-Con where they do nothing but teach these techniques to industry professionals all over the world:
http://www.synaudcon.com
I've not taken any of these courses, but I'm current with most all of the literature they teach from....ironically, frequency response is way down on the bottom of the priority list for their classes.

Sound System Engineering by Don Davis also covers many of these topics. Anything put out by Heyser is a great read too....he's the one that pioneered time domain spectrometry in the first place and started correlating the time response and explaining why systems that measured flat could sound horrible.

Btw, I never said I go without EQ....I just don't EQ acoustic problems because it doesn't work well - emphasis on well, because mediocre is not acceptable in high fidelity environments. You absolutely have to use EQ for the direct response of the speakers and to compensate for any acoustical loading from nearby boundaries, but those aren't "acoustic _problems_". So although everyone has many forms of EQ in their equipment rack (, we use it for taming feedback too, but that's really a fault of the polar response of the speakers), we're almost never using it to "tame a room"....it's as absurd a concept as the tire/axle analogy.


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## brucek

> You absolutely have to use EQ for the direct response of the speakers


Would this imply that Audyssey and REW measurements should only be carried out near field with no listening position measurements?



> I just don't EQ acoustic problems because it doesn't work well


Does this include modal peak EQ?

brucek


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## Kal Rubinson

tonyvdb said:


> Even the best recording studios/auditoriums and concerts use equalizers between the board and the speakers to ensure the sound is output flat. If you choose to go without thats your choice however its not a general consensus.


Only for music in electronic form. The concerts I attend are acoustic.


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## DrWho

brucek said:


> Would this imply that Audyssey and REW measurements should only be carried out near field with no listening position measurements?


At the very least it means you should use time-gating of the impulse response before you run the FFT. The newer Audyssey algorithms already do this, in addition to a few other things...like not compensating for room gain (which I think is effectively what people here are trying to accomplish with house curves...)

I think the coolest thing about REW is that it's free and offers time-gating....I don't think I've seen anyone else using it on this forum? I only browse through here periodically, so I might have missed it.

Ground-plane measurements outdoors can be invaluable, but you still need to measure in room to account for the boundary gain effects - especially with speakers that don't have constant directivity or flat power response (because the boundary effects become even more non-linear with frequency).



brucek said:


> Does this include modal peak EQ?


That's a gray area for me because it's technically not minimum phase, but it's really close. I've been in some rooms where it worked quite well, and then others where it really didn't work at all. I haven't quite figured out what to look for to determine ahead of time when that will be the case, but like all things audio, gotta do a sanity check with your own ears.

I will probably always think modal peak EQ is a compromise, but I can see how it can be an effective technique when fixing the room acoustics isn't an option.


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## Mikkel

What a wonderful thread (with lots of great info)... even if it's been dead for a few years.
One question based on Dr.Who's statements: Is it possible to (in this order) 
a) set the time window in REW
b) run auto-eq
c) export the filtered IR?

If in fact yes, would anyone help me in telling me how?


Best regards,
Mikkel


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## EarlK

Mikkel,

> The problem here is that you ( & maybe Dr. Who ) believe that REW can take the place as a standin for TDS (TEF) .

> It can't, because REW applies its' ( Single ) time window onto the complete impulse ,( it is simple, single-event, post, data-capture windowing ) .

> ( In laymans terms ), TEF applies a slew of time-windows ( which vary with frequency ) around the capture sweep, as that sweep proceeds bottom to top .
( so it is, Multi-Event, Coincidental, Data-Capture Windowing ) 
> Sorry for my obvious use of some really tortured, "Manglesh" .:dumbcrazy:

> BTW, both approaches lower the resolution of the displayed FR , it's just that TEFs' TDS approach has a few more practical uses within noisy environments ( though one needs to understand that "response - smoothing" is already builtin to it's captured data ) .

> I speculate that Dr. Who thought that REWs approach ( single-window, post-processing ) could emulate the functions of TDS/TEF allowing him to EQ only the speakers ( & not the room ) .

> BTW, this forum is mostly populated by those who figure EQ can fix their rooms acoustical short-comings ( when it can't ). 
> Dr. Who ( from his comments was clearly on the side that it's best to treat a rooms problems with room treatment & leave the EQ to fix a speakers response shortcomings .

> If you want to play with "Windowing", then hit the IR Window button & have at it ( bring in the right-hand side of the window to say 40ms & then look at your FR ). Make it even narrower and look at the resulting FR / I certainly wouldn't Auto-EQ anything based on lowering the time resolution of the captured IR .

> Anyways, maybe this ( playing with the IR window ) will trigger an epiphany of sorts for you ( ie ; that theres no free-lunch when it comes to fixing poor room acoustics ) .

:sn:


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## Mikkel

I'm reminded every day I go to work that there is no free launch :sad: Also, everyday also my hi-fi hobby seems to show the same sad truth 

Anyway, I should have been more precise: if it is possible to assign different windows for different frequency bands. After using my head and looking a bit more detailed at the manual and REW-interface the answer seems to be no.
Your answer clearly shows the same.

As you may have guessed I'm fiddling my way into DRC but also want to only correct the direct signal and not the reflections by adjusting the IR window (for different frequency bands). I was hoping REW could help instead of the free DRC-alternative (which is a challenge for my amateur knowledge)... and which delivers a sound much below the unfiltered response (probably because I need to fine-tune some wicked setting somewhere in the config).

Anyway, thank you very much for your response 


EDIT: I'm on the "dark side" as well. I've treated my room as much as practical (the limiting factor ;-)). But am struggling with a mid-range frequency problem I was hoping DRC could solve... as well as a few boosts in the 20-200hz range. Oh well, I'll keep searching for the holy grail (whether in DRC or elsewhere)


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## EarlK

Mikkel said:


> As you may have guessed I'm fiddling my way into DRC but also want to only correct the direct signal and not the reflections by adjusting the IR window (for different frequency bands). I was hoping REW could help instead of the free DRC-alternative (which is a challenge for my amateur knowledge)... and which delivers a sound much below the unfiltered response (probably because I need to fine-tune some wicked setting somewhere in the config).


> Which process ( REW or DRC ? ), delivered a less than optimal result when you convolved its EQ file ? 

*As a Review ;*

(i) One can export the EQ Correction file as a Wave file ( that REW has generated ) .

(ii) That EQ Correction file can then be convolved through something like ConvolverVST ( which itself needs to be hosted by some sort of software that hosts VST style plugins.

> Have you already done this with REW ? ( I find your language is not precise enough to completely follow ).

> You'll get better sounding results ( when fixing a speakers EQ curve ) if you take ( as you guessed ) as much of the Room Acoustics out of the equation . 
> For me, that means measuring the speaker maybe only 2 ft away & ignoring/cancelling Auto EQ filters that are obviously trying to fix Room Acoustic problems .

> One needs to have your Exported EQ Correction File ( IR ) starting at "T"=0 .
> Ie; You don't want to have a builtin delay on that EQ Correction File ( because you'll generate funny sounding phasing & flanging artifacts ) . So ;
> Try going into the Impulse Window, Hit the Button called "Estimate IR Delay"
> A window will come up telling you the delay, it will ask you if you want to "Shift IR" ?. Confirm this query by hitting the "Shift IR" button. 

> Now run REWs auto EQ session & the Export it as a "Normalized" wave file. Hopefully that sounds better .



:sn:


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## Mikkel

I apologize for the lack of understanding.

DRC performs less than optimal judging by subjective listening. It sounds dull. DRC and REW-exported filters generate aproximately the same frequency filtering but REW sounds more open.

Anyway, so you suggest:
1) Recording the frequency response close to each speaker, e.g. 2 feet
2) Estimate IR-delay
3) Run auto-eq
4) Export the filtered IR (EDIT: Or did you mean only export the impulse response? In that case, should I check the "invert impulse" in the impulse response settings?)

Did that sum it all up?

As for what I've done up until now:
I have in fact measured each speaker from the listening position in REW, run auto-eq, exported the filters into Jrivers convolution engine. I didn't press estimate IR-delay. I can see how this is a mistake! This approach doesn't suit me since I'm correcting room response which may work well for me in the sweet spot but not for the one sitting next to me in my HT.

I have also tried exporting the impulse response as a wave, run them through DRC by Dennis Sbraigon and used the DRC-filters in Jrivers convolution engine. As mentioned they sound a bit dull/tame - or perhaps I'm interpreting the result incorrectly (e.g. perhaps dull is a consequence of delay and phase correction).


Best regards,
Mikkel


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## EarlK

Mikkel said:


> Anyway, so you suggest:
> 1) Recording the frequency response close to each speaker, e.g. 2 feet
> 2) Estimate IR-delay
> 3) Run auto-eq
> 4) Export the filtered IR
> 
> Did that sum it all up?


> Again, your language structure is incomplete ! You *left out *the most* important part* of my message !

ie;* " Point 2) Estimate IR-delay "*

> It is not sufficient to only "Estimate IR-Delay" / One must actually choose to *Correct that Delay* back to "T=0" ! :hissyfit:

:sn:

PS ; As a follow-up to the above, I would recommend that you use jRivers' Parametric EQ Plugin to match ( as close as possible ) the correction filters generated by REW . That way you will have a useful platform for comparison, to determine if all this effort ( to create convolved EQ ) is worthwhile .


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## Mikkel

It is 0 by default, but I did check that T=0. We could switch to Danish (my native language) if it will benefit our mutual understanding :devil:

But seriously, thank you for your help


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