# REW EQ Filters



## Phillips (Aug 12, 2011)

Hi when using suggesting filters generally should we:

0-300hz use filters for individual speakers left and right
300-20,000 use filters for combined speakers

Or the other way around?

For imaging if the individual speaker frequency response is within +-1db the imaging will be ok though imaging cant actually be measured?

Thanks in advance


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

Your initial inclination is correct:


Phillips said:


> 0-300hz use filters for individual speakers left and right
> 300-20,000 use filters for combined speakers





Phillips said:


> For imaging if the individual speaker frequency response is within +-1db the imaging will be ok though imaging cant actually be measured?


The speakers will never actually measure +/- 1 dB in the upper frequencies, but imaging will be fine in spite of that. For some reason, introducing EQ filters in one speaker or the other to “correct” deviations in response does weird things to the imaging in the frequency range of the filter.

Regards, 
Wayne


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## Phillips (Aug 12, 2011)

Hi Wayne thank you

The reason I ask, I thought that bass was mono so should be EQ mono?

Some auto equalizers eq bass as combined?

Thanks again


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

Phillips said:


> Hi Wayne thank you
> 
> The reason I ask, I thought that bass was mono so should be EQ mono?


 It’s not so much that as it is that EQing the lower frequencies separately doesn’t mess with imaging. T here’s plenty of info between ~300 Hz and the lows. It’s probably has more to do with the so-called transition frequency, the point where the sound becomes omnidirectional, or more specifically difficult to localize due to the effect of the room. 

Although I’ve never run any actual experiments, I’ve often speculated that the actual transition frequency can vary from one room to another, and also with distance from the speaker. Something like filtered pink noise could confirm this, but I expect that someone with say, a desktop system in a fairly dead room could localize frequencies maybe even below 300 Hz, while someone with a more live room sitting 12 ft. back might not be able to localize anything below 500 Hz so.

Regards, 
Wayne


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## Medi0gre (Oct 30, 2012)

Would this all be related to the Schroeder frequency?


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

Yes.

Regards,
Wayne


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## Phillips (Aug 12, 2011)

Hi Wayne with Antimode Dual Core 2.0 (full range) it seems to do mono filters from about 15-250hz, measure with REW separately and dips and peaks, when measured the response smooth's out.

Please don't think I am arguing with you


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## FargateOne (Mar 3, 2015)

Phillips said:


> Hi when using suggesting filters generally should we:
> 
> 0-300hz use filters for individual speakers left and right
> 300-20,000 use filters for combined speakers
> ...


Thanks Phillips for asking because I was a little bit confused how to reconcile your post and Wayne's in my most recent thread.
(http://www.hometheatershack.com/forums/rew-forum/141105-after-1-month-dead-end-eq-rew.html)
I was afraid to ask for more info. What I understand is to EQ left and right fronts separatly for 0 - 200hz (more or less). I am still trying to find a good set of filters for both fronts at higher frequencies (1k to 20k)

I have tried others EQ filters settings (I reduced the number by half) . It is difficult for me to find what is best.

That is not a REW problem because, I must to say, that I am amazed how there is no differences between the predicted curve in REW EQ and the measurements of the frequencies response with EQ filters suggested by REW.


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## Phillips (Aug 12, 2011)

FargateOne said:


> Thanks Phillips for asking because I was a little bit confused how to reconcile your post and Wayne's in my most recent thread.
> (http://www.hometheatershack.com/forums/rew-forum/141105-after-1-month-dead-end-eq-rew.html)
> I was afraid to ask for more info. What I understand is to EQ left and right fronts separatly for 0 - 200hz (more or less). I am still trying to find a good set of filters for both fronts at higher frequencies (1k to 20k)
> 
> ...


I found when using EQ try halving the Q value I found this to work.


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

Phillips said:


> Hi Wayne with Antimode Dual Core 2.0 (full range) it seems to do mono filters from about 15-250hz, measure with REW separately and dips and peaks, when measured the response smooth's out.
> 
> Please don't think I am arguing with you


Hey Phillips,

Sorry but I don't understand what you were trying to say.

Regards,
Wayne


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## Phillips (Aug 12, 2011)

Wayne A. Pflughaupt said:


> Hey Phillips,
> 
> Sorry but I don't understand what you were trying to say.
> 
> ...


Hi Wayne not good description, sorry about that try again

I have a Antimode 2.0 Dual core which does Auto EQ from 0-500hz but has full range parametric EQ.

When I use the Auto EQ it seems to correct the combined response. The reason I think this is when I measure each speaker separately the response has peaks and dips, but when I measure combined response it is alot better, though not ideal. 

The question is Auto EQs seem to use this way which is different to what you are saying?

Thanks again


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

Phillips said:


> The question is Auto EQs seem to use this way which is different to what you are saying?


You mean because the Antimode combines up to 500 Hz, but I recommended doing that only to 300 Hz?

Regards, 
Wayne


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## Phillips (Aug 12, 2011)

Wayne A. Pflughaupt said:


> You mean because the Antimode combines up to 500 Hz, but I recommended doing that only to 300 Hz?
> 
> Regards,
> Wayne


My apologies red somewhere and It looks like it EQs up to a certain frequency 300hz does ring a bell. Then from there it leaves the rest to manual EQ.

Ok I thought you suggested Left and Right, using separate filters for each speaker up to 300hz

Cheers


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

I’ve generally suggested using separate filters (if needed) up to 300 Hz, but matching filters above that point. The exact “point” may vary somewhat from one room to the next, depending on its liveness and the distance from the LP (e.g. the Schroeder Frequency).

Regards, 
Wayne


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## Phillips (Aug 12, 2011)

Wayne A. Pflughaupt said:


> I’ve generally suggested using separate filters (if needed) up to 300 Hz, but matching filters above that point. The exact “point” may vary somewhat from one room to the next, depending on its liveness and the distance from the LP (e.g. the Schroeder Frequency).
> 
> Regards,
> Wayne


Hi Wayne thank you, again, I might try some measurements this weekend.


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## BloomBloom (Feb 15, 2013)

Wayne A. Pflughaupt said:


> I’ve generally suggested using separate filters (if needed) up to 300 Hz, but matching filters above that point. The exact “point” may vary somewhat from one room to the next, depending on its liveness and the distance from the LP (e.g. the Schroeder Frequency).
> 
> Regards,
> Wayne


Hello Wayne, 
I don't mean to hijack his thread, but can I ask you to clarify this point:
Woud you suggest individual L & R EQ filters bellow 300Hz in a system that includes two speakers and one sub? 

It's new to me the idea to EQ the speakers separately (Below 300HZ) because in most guides they do both speakers together. 

Thank you!


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## BloomBloom (Feb 15, 2013)

BloomBloom said:


> Hello Wayne,
> I don't mean to hijack his thread, but can I ask you to clarify this point:
> Woud you suggest individual L & R EQ filters bellow 300Hz in a system that includes two speakers and one sub?
> 
> ...


Hi,
Not sure if you guys saw my question? 

I have a two channel system with a sub that's fed by L+R channels from the DAC - so I can't EQ the sub separately. So far I've used matching filters (L+R, sub and main speakers) below 300Hz.
I did measure the left speaker withe the subs left channel on their own and the same for the right speakers and sub channel. 
I was under the impression you should use matching EQ filters otherwise it messes up the imaging - but if I understand you correctly that's not the case?

Thank you!


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

Sorry BloomBloom, your question from a few weeks ago somehow got past me.

For a 2-channel system as well as surround sound, its best to EQ the front L/R speakers with matching filters above 300 Hz or so. Below that point mis-matched filters can be used without effecting imaging, but you probably should go ahead and stay with matching filters below 300 Hz in your case, since the sub and main speakers are using the same equalizer.

Regards, 
Wayne


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## BloomBloom (Feb 15, 2013)

Cool Thank you!


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