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Hi,

I'm looking for an audio interface with a parametric EQ that supports lowering the volume of a very narrow frequency band to counteract bass boom -- standing waves -- in my living room where I have my Hauptwerk organ console. It's basically only a few notes in the bottom octave of the pedals that are affected, F-G-A.

Can the Revelator io24 do this?

Relatedly, does the parametric EQ apply to all outputs, or can it be configured to only affect the speaker outputs, as the headphones obviously don't have the same problem.

Thanks,

Colin
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by SwitchBack on Sat Aug 19, 2023 4:26 am
The answer depends on the equalizer you choose. The standard 4-band EQ goes as high as Q=10.

But note that unless the offending sound is a pure sine wave you'll also find peaks at every multiple of the fundamental frequency. You may need a lot of filters to mute one single sound (and do harm to the remaining signal in the process).
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by colinthart on Wed Aug 23, 2023 7:49 am
The higher frequencies aren't as much of a problem; the resonance is caused by standing waves at low frequencies, with the lowest octave being the worst.

What does "as high as Q=10" mean? The narrowness of the band (which is what I need) or the amount of attenuation? I need to attenuate by 3DB at least.
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by SwitchBack on Wed Aug 23, 2023 8:25 am
The standard FAT PEQ has gain ranging from -15dB to +15dB and a Q (=1/bandwidth) ranging from 0.1 to 10 for each of the 4 bands.

Q (quality factor) = fc (center frequency) / 3dB bandwidth (distance between 3dB drop-off or gain frequencies). So a more narrow filter has a higher Q. link

NB. Did some testing. The link is about energy and power hence the 3dB value. For a PEQ it's about 'half gain': Q = fc / half-gain bandwidth. So for fc=1kHz, gain=-12dB and Q=2 there's 500Hz bandwidth between the points on the curve where gain is -12/2 = -6dB.

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