Lows very boomy when EQ'd to flat

[jan.didden]

When I EQ my subs (~100Hz xover to ESLs) for reasonable flat response on REW with a UMIK-2, they sound extremely boomy and much too loud.
When I set the sub level to what sounds to me like a reasonable level matched to the main speakers, and I measure with RTA, the sub level is almost 15dB lower than the main speakers.
What could cause that descrepancy? Could it be some setting in the measurement I may have missed?
I used the standard swept sine method.

Jan

 

[John Mulcahy]

If you are on Windows it could be because noise cancellation processing is being applied to the stereo output of the mic, rolling off the low end. That should not happen if you use the WASAPI exclusive device entry (name starts EXCL).

 

[ddude003]

What ESLs and Sub(s) do you have? And the Pre, Amp or AVR? And wondering how and/or why you crossover at ~100Hz? Size of room and any room treatment?

 

[AudiocRaver]

I gave my opinion on your other thread, over here.

 

[jan.didden]

I gave my opinion on your other thread, over here.

Yes that sounds similar to what I have. But it doesn't make sense, does it. If the mike measures it flat, why would it sound boomy.
I'll check out John's suggestion tomorrow.

Jan

 

[AudiocRaver]

It's a mystery.

 

[jan.didden]

What ESLs and Sub(s) do you have? And the Pre, Amp or AVR? And wondering how and/or why you crossover at ~100Hz? Size of room and any room treatment?

I'm not sure what the equipment brand has to do with it?
Room is about 10m long, 6m wide, 4.6m heigh. Speakers are in the middle, pretty much standing free.
Some damping panels on the walls.
I tested with both 2nd order and 4th order xovers. Not much difference in the anomaly I mentioned.

Jan

 

[jan.didden]

It's a mystery.

Today's mystery is tomorrows knowledge ;-)

Jan

 

[ddude003]

I'm not sure what the equipment brand has to do with it?
Room is about 10m long, 6m wide, 4.6m heigh. Speakers are in the middle, pretty much standing free.
Some damping panels on the walls.
I tested with both 2nd order and 4th order xovers. Not much difference in the anomaly I mentioned.

Jan

Knowing what equipment you have would allow us to read the specs and get a feeling for what might be going on with any combination, connection issues and gain structures... If they are just panels or also have woofers, firing forward and/or rearward, frequencies and so forth... Are the Subs passive or active and what are they driven by, does your amp double down when your ESL dive down in impedance when the frequency goes up... Lots of things to consider... Never mind...

 

[jan.didden]

One idea a friend gave me: I am using the sine sweep test signal. Could it be that the 'dwell time' at the low frequencies is too short for the room modes to build up, while with music playing, they have that time.
That would mean that the measurement will be lower than the perceived strength with music.
Maybe try stepped sine measurement, although that seems to be meant for distortion measurement, but should also show fundamental?

Jan

 

[John Mulcahy]

Could it be that the 'dwell time' at the low frequencies is too short for the room modes to build up

No, a common misconception arising from a misunderstanding of how sweep measurements work. The sweep is the stimulus, the mic captures the response. The ratio of response to stimulus yields the transfer function. The response to the low frequency part of the stimulus has the entire duration of the sweep plus additional capture time after the sweep ends to be included in the calculation.

 

[jan.didden]

Thanks John, that's useful.
I'll attack this again in the weekend when I have some time.
If the WASAPI (EXCL) doesn't solve it, where should I look next?

Jan

 

[John Mulcahy]

Make sure enhancements are not enabled on the Windows audio input properties Advanced tab (System - Sound - Related Settings on right hand side - Sound Control Panel - Recording - select UMIK, click Properties button) or Enhancements tab. Some PCs may have a separate application with similar features, e,g, Waves MaXXAudio, HP Audio Center, myASUS.

 

[jan.didden]

Thanks!

 

[jan.didden]

Make sure enhancements are not enabled on the Windows audio input properties Advanced tab (System - Sound - Related Settings on right hand side - Sound Control Panel - Recording - select UMIK, click Properties button) or Enhancements tab

That fixed it John! At the Enhancements tab, there are several enhancements you can select, one of them being 'low frequency protection' or something like that.
None of the enhancement were selected, but there's an overall selection 'disable all enhancements' which I selected.
Now the apparent bass closely tracks the frequency response in the analyser.
I did not find a similar enhancement menu in the audio output dialog, so apparently it is only available for inputs (in this case the UMIK-2).

So, on to explore more REW wonders ;-) !

Jan

 

[AudiocRaver]

Cool. Glad you figured it out.

 

[jan.didden]

Thanks to JM.

 

[Johnnie]

What ESLs and Sub(s) do you have? And the Pre, Amp or AVR? And wondering how and/or why you crossover at ~100Hz? Size of room and any room treatment?

I also have (4) subs crossed over higher. Equalization frequencies in sub setup is many times that of the AVR for main speakers. If you can spread your subs around the room generally equally from the listening position you can cross them over higher with better results (confirming with REW).