REW measurement of 2.1 system - would you EQ and where/how?

[JohnPM]

The response looks typical of one where a measurement is being used as cal data. You have selected "Use loopback as cal and timing reference" but from your system description it doesn't look like there would be a way to have a loopback cable connected, which from your selections would need to go from the right output channel to the left input channel. You haven't made any device selections in REW, leaving them as the Windows defaults, so can't tell what you are using for output or input. If the input is a USB mic you can't use any loopback timing options.

 

[Joffy1780]

The response looks typical of one where a measurement is being used as cal data. You have selected "Use loopback as cal and timing reference" but from your system description it doesn't look like there would be a way to have a loopback cable connected, which from your selections would need to go from the right output channel to the left input channel. You haven't made any device selections in REW, leaving them as the Windows defaults, so can't tell what you are using for output or input. If the input is a USB mic you can't use any loopback timing options.

Thank you, not sure how I managed it. Really frustrating thing is I get the chance to do this once in a blue moon.

 

[johny_2000]

Lastly, REW's default sweep is useful in that it captures FR, HD, phase, GD, ... all at the same time.

However, for assessing in-room frequency response you're much better off using Pink noise with the Moving Microphone Method.

Could you tell me more about the second option please?

Is this similar to this article? https://mehlau.net/audio/room-correction-peq/index.html

 

[staticV3]

Could you tell me more about the second option please?

Is this similar to this article? https://mehlau.net/audio/room-correction-peq/index.html

Yes. That article describes MMM.

Here's the original whitepaper on MMM:

https://www.ohl.to/audio/downloads/MMM-moving-mic-measurement.pdf

 

[johny_2000]

Yes. That article describes MMM.

That's what caught my attention. And I'm still thinking.

Note: In-room speaker responses are non-minimum phase but PEQ can only correct minimum phase problems. It can not fill any dips caused by non-minimum phase issues. Any attempt could result in a massive waste of amplification power and might drive the speaker into audible or even damaging distortion. The spatial average of the captured speaker response above is blind to phase hence it is safer to apply only cuts and no boost. This is ensured by setting "Individual Max Boost" and "Overall Max Boost" to 0.

This is true? Should PEQs only use attenuation (-dB) and not use gain (+dB)?

 

[staticV3]

That's what caught my attention. And I'm still thinking.

This is true? Should PEQs only use attenuation (-dB) and not use gain (+dB)?

No. You can design a cut filter as described in your quote using purely boost filters.

The fact that every PEQ system is accompanied by a Preamp which ensures no digital clipping, means that you can use whatever filter you want with whatever parameters you want, and the final PEQ filter will end up a cut filter (only attenuation).

All that matters is the final frequency response of the filter, not what parameters you used to arrive at it.

That being said, it's very true that you'll get nowhere trying to fill in bass nulls using EQ. Nasty distortion and a loss in headroom is all that awaits you.

 

[johny_2000]

That being said, it's very true that you'll get nowhere trying to fill in bass nulls using EQ. Nasty distortion and a loss in headroom is all that awaits you.

In other words, the bass of any speaker is pre-determined by design, and attempting to amplify it with PEQ is a waste of time and resources.

 

[staticV3]

In other words, the bass of any speaker is pre-determined by design, and attempting to amplify it with PEQ is a waste of time and resources.

No, absolutely not.

You can boost a speaker's bass response using EQ and achieve excellent results.
It's what most of the very best studio monitors do to arrive at a flat frequency response.

You just can't fix bass nulls, an issue of room acoustics, using EQ.