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Subject: Re: [motm] MOTM-410 Gain question.

From: "jhaible" <jhaible@...>
Date: 2002-01-20

> The output level depends a great deal on the settings. I many settings,
the
> level is quite low compared to the input signal amplitude. However, in
the
> lower end of the frequency settings, output levels and easily be 13 V
> peak-to-peak with a singe MOTM VCO feeding in. So, if you cranked up the
> gain in the circuit for the other situations, these settings would surely
> cause clipping. So, I expect your 410 is normal. Even on the dry
setting,
> with about 9 volt peak to peak input, I have only about 4 - 5 volts
> peak-to-peak output on mine. These are just my observations.

Larry is right. That's a general "problem" with resonant filters: Their gain
depends a lot on the harmonic contents of the input signal and the setting
of the filter - that's what this whole VCF stuff is about.
Normally, you want to avoid hard clipping of the output stage by any means,
so it's better to design it that way. You always can add gain afterwards,
(in the next module, or at the mixer or amp) but you cannot remove clipping
once it happens.
Most VCFs have an ∗internal∗ means of (more or less) soft clipping for
high resonance (or even self oscillation). This makes the output level
situation better (yes, otherwise it would be even worse!), and it's also
an important factor of a specific filter's genuine sound. You would not
want the filter's own behaviour obscured by a clipping output stage.

JH.