# Cannot remove peak at 80hz



## lovingdvd (Jan 23, 2007)

Hi all - just got finished using REW w/ BFD to eq my sub with my new Yamaha RX-V1800 receiver. Overall I feel the calibration went excellent. However I have one nagging issue I can't tame that I'd like your feedback on please...

I use a house curve of 20 8.0, 80 0.0 and obtained a nice smooth response along the curve. The challenge is that I have some peaks in the 75-95hz range THAT ARE COMING FROM THE FRONT SPEAKERS, not my sub.

I tried making various changes with filters to address it, but these filters do not help (not surprisingly because the issue is with the mains).

Take a look at the attached graphs to see the peak. The first screen shot is with the mains + sub, the second is just the front. Both have 1/3 octave smoothing applied.

My main challenge is that I have no way to equalize the mains. The Yamaha uses YPAO to balance things out which I like to use. However with this engaged I cannot also then use its manual EQ function to remove these peaks in the 80hz area.

The main thing I am wondering is how important it is to remove this peak. It seems to be about 6db or so, which seems significant but not necessarily horrendous. So I'm thinking that perhaps its not going to make a big difference to remove it and therefore just not worry about it. Or is this worth focusing on?

The other thing I'm wondering about is how I can even go about addressing this. I don't want to lose the YPAO functionality because it adds benefits outside of the sub range. And with it I then have no manual eq option for the mains.

Any advice greatly appreciated!


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## brucek (Apr 11, 2006)

> The other thing I'm wondering about is how I can even go about addressing this.


Adjust the subs phase control and the receivers sub distance setting...

brucek


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## lovingdvd (Jan 23, 2007)

brucek said:


> Adjust the subs phase control and the receivers sub distance setting...
> 
> brucek


Thanks - I'll experiment. So even though the peak is there independent of the sub being on, those settings could still help. Not sure how, but I know you know what you are doing so its worth a try!!


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## lovingdvd (Jan 23, 2007)

OK I came across something strange I hope you have some insight on...

I tried adjusting the sub distance (+ and -), the sub phase, and even the mains distance (+ and -) in all sorts of combinations. Nothing took out the peak at 80 so I put all those settings back to how I had them originally.

HOWEVER then I discovered something quite odd... 

Basically I was giving up and just planning on living with the peak at 80. After I did my final measurement I did some listening and decided the sub was outputting at a bit lower volume than I prefer.

So I used the volume level on the sub to increase things some - I guess it was about 5db. Then before finishing for the night I decided to remeasure.

I was quite surprised to see the peak at 80 was just about gone! Also my curve was slightly different and improved in some ways. I now had a couple db dip at about 22hz and 60hz which I fixed with a +2 gain filter (I know, I know but i can't help it!  )

Bottom line is that my curve now looks near perfect. HOWEVER I am quite confused... why would I get one curve and slope at one db level of the sub, and something different at high or lower levels?

So anyway after I was done I took a few more measurements and found that with my overall system level db changing (i.e. very loud vs. loud vs. average level etc) I would get different response curves from REW.

So I'm left wondering - what is my real response curve? Is my system now properly eq'ed only for a particular listening level? Thanks!


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

I was waiting to see what your phase and distance changes got you before commenting, but yes, more of than not any “won’t equalize away” issues up that high can be attributed to the mains.



> I now had a couple db dip at about 22hz and 60hz which I fixed with a +2 gain filter (I know, I know but i can't help it!  )


Filters with that small of a gain change may or not be audible. In this case I wouldn’t worry about the boost so much as the bandwidth. E.G. avoid ultra-narrow filters.



> HOWEVER I am quite confused... why would I get one curve and slope at one db level of the sub, and something different at high or lower levels?


Such is the nature of in-room measuring. You can’t get a perfect replication of displayed results from one month to the next, or day to day, or even in the same session. Kinda makes it difficult to craft perfect modal filters...



> So anyway after I was done I took a few more measurements and found that with my overall system level db changing (i.e. very loud vs. loud vs. average level etc) I would get different response curves from REW.


Yup. Kinda makes it hard to... Nevermind.  



> So I'm left wondering - what is my real response curve? Is my system now properly eq'ed only for a particular listening level? Thanks!


I think you’ll find that even though on-screen results will look a little different from one session to the next, you won’t notice any _audible_ change. Just get it where it sounds right to you, and start enjoying your superb-sounding subs. 

Regards,
Wayne


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## lovingdvd (Jan 23, 2007)

Actually what is kind of unexpected is that I can get almost identical measurements / slopes with repeat readings. Even after I break things down and set up again another night. Where things go awry is when I change the output level of the AVR or on the sub - then the readings change quite a bit - that is unexpected, and leaves me wondering just what my curve really is...


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## thxgoon (Feb 23, 2007)

Hey lovingdvd, this might be a bit OT but.... is there anyway you could take a full range measurement (20-20,000) of your system before and after YPAO? I've always been curious to see how response is affected.


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## clubfoot (Apr 12, 2007)

lovingdvd said:


> Actually what is kind of unexpected is that I can get almost identical measurements / slopes with repeat readings. Even after I break things down and set up again another night. Where things go awry is when I change the output level of the AVR or on the sub - then the readings change quite a bit - that is unexpected, and leaves me wondering just what my curve really is...


It maybe a matter of the sub/amp efficiency at low volume levels. Once the volume is high enough to drive the sub properly you get a good graph/output. It could also be a defective unit?!


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