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Reverb equalization is provided through Q82, an OpAmp having equalization
to establish low frequency response and with s81 and R86 forming the high
frequency selection circuit. Up to 10 dB of peak EQ is provided at center
frequencies of 1. 1, 2. 2, 3. 4, 4. 5 and 6. 0 KHz.
The Control Amplifier section consists of Q61 in a phase splitter circuit
which is full wave rectified to provide both positive and negative currents
to modify the OTA gain control stage. The output of this circuit boosts
or cuts the OTA output gain to quickly cut off the reverberation signal
(short time decay), or to amplify the existing reverb signal trail (long
decay). The output of the Q61 stage is mixed through voltage divider R67,
R68 and R69, with potentiometer R70 selecting the amount and polarity
required for the effect desired.
NOTE: The decay control circuitry is gated by the output signal.
This can cause operation of the reverb channel when the REVERB control
is minimum (counterclockwise) and the DECAY control is also minimum
(counter-clockwise).
This design provides greatest flexibility of the decay control
for special effects when used with the reverb mix control but should
be recognized by the user when such special effects are not desired.
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