Tiptop Z2040 4-Pole VCF - Manual (Page 6)

0db:
In this spot the unique resonance-gain-compensation
circuit will kick in, providing a gain compensation of the
input signal as the Resonance is increased. This gain
compensation loop dramatically reduces the drop in
volume of the input signal when the Resonance is
increased, in turn, producing resonating sounds with
additional “punch.”
Just past 0db - MAX:
This range causes the Z2040 to behave in a non-linear
fashion which can result in some very interesting sonic
results.
In this range any sound wave with a magnitude of
10Vp.p (Z3000 waveforms, for example) will be clipped
by the filter core. This clipping will get deeper as gain
is increased. This kind of filter core clipping is soft and
smooth and will add harmonics to the incoming sound.
When the Resonance is increased in this range the
output gain (volume) will increase as well, and at
maximum settings will output a signal of up to 21Vp.p!!.
This special feature is inherent from the structure of
the resonance-gain-compensation and will cause
the Output to add additional clipping and distortion to
the filtered signal and the resonance sine shape. The
Output signal amplification adds a 'hard' sound clipping
by driving the Output Op Amps to their rails. This high
gain could also prove useful to drive other modules
following the Z2040 in the signal flow to make them
distort and clip the signal even further.