Over Attenuation on Filter & Mixer?

[Ted3000]

Just wondering if this is normal Moog behavior.

1. As the M-32's resonance is raised, the filter signal gets quieter. A lot quieter. I don't remember past Moog filters losing so much volume with resonance. Normal? I know some filters do this, didn't know the good old Moog ladder was one of them. (My last analog Moog was a Prodigy owned over 10 years ago, I can't recall if it shed so many db's.)


2. Mixer for the oscillator/noise or external in: Turning knob from left to right, I'd expect that the oscillator volume would stay at full gain, while slowly fading in the second signal. At noon, you'd have full volume of both, then it would fade out the osc on the second half of the turn. Instead, the mixer knob is fading out the oscillator the entire turn. It's half volume by noon. So you can have loud osc at full left, or loud noise/external at full right, or both at the same time - but both much softer.

Are these gain behaviors to preserve headroom? I thought that was more of a concern with digital audio... Any wisdom appreciated!

[Wesley]

Item 1 is a common way for resonant filters to behave. There will be variance in designs, and the type of waveform sent to the filter can affect response too.

Item 2 is normal behavior. It is described just as you are experiencing it in the owner's manual.

[Vsyevolod]

Yes it is exactly as described in the manual (speaking here of point #2). There are ways to design around this which is common with other manufacturers. Sometimes called 'equal power X-fading' it keeps the volume of the first voice high until about 11:00 where it starts to attenuate it. Likewise, the volume of the second voice stays high until about 1:00 (turning it CCW). While I agree with your comment that this would be nice to implement, such things can be counter cost effective which I believe Moog were trying their darndest to be.

Stephen




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