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You can get the schematics PDF here.

You will see that the main active ingedients are the two groups of two VCAs that form the two faders. Normalization through the jack connectors is used to let each VCA pair act as either crossfader, panner or two VCAs where one opens while the other closes. The two VCA CV processors create the control voltage curves according to the -3dB middlepoint law that will give an equal loudness curve when crossfading or panning.

For crossfading you connect two signals to e.g the A1 and A2 inputs and listen to the AX/L output while leaving the AR output unconnected. For panning you send one signal to e.g the A1 input and connect the AX/L and AR outputs to e.g. the left and right input of a stereo mixing desk channel. When connecting two signals to the A1 and the A2 inputs and connecting the Ax/L and AR outputs to two different channels on the mixing desk you can fade in one channel while the signal on the other channel is faded out. (If you would use an envelope follower on one of the input signals this would create a ‘ducker’, where a signal is faded out automatically when another is increased in level.)

Note that all the signal inputs and the modulation inputs can accept both audio rate signals and LFO rate signals, so whatever you can do with an LFO or envelope generator you can also do with an audio signal. So, you can e.g. modulate audio at an LFO rate, but e.g. also crossfade between LFO signals at an audio rate!

Extra is a signal path from an internal crossfade mix from the fader inputs to fader B. There are three modes available for this mix:

Mode AX MIX lets the A mix signal go to both inputs of fader B. In this mode one can mix two signals with fader A, and fader B will pan the mix to the BX/L and BR outputs, provided both of these outputs have a jack in their connector. So, one can use this to mix two signals and pan them in stereo, or to two different audio processors.

Mode AX>BL lets the mix from fader A go only to the B1 input of the second mixer. In this mode an additional audio signal can be routed to input B2 to be able to mix three signals; first set the mix of the two signals on the A inputs and then fade between this mix and the third signal on the B2 input and get the total mix from the BX/L output.

In mode AX RM the mix from fader A is routed in normal phase to the B1 input and in inverted phase to the B2 input. In the middle position of the B fader the mix will be cancelled as the input signals on B1 and B2 are in opposite phase, with silence as a result. The B fader knob and the B modulation input will now crossfade between the mix signal and the inverted mix signal, which actually is what ringmodulation does. So, in this mode you can use the module as a ringmodulator. Due to the nonlinear crossfade curve there will be some distortion in the ringmodulation, and the modulation depth will define the amount of distortion. But as the curve now has sort of a compressing effect on the modulation waveform a triangle wave will be sort of compressed to a sinewave at a certain modulation depth and fine tonal control can be achieved by setting the modulation depth at certain levels for certain modulating waveforms. E.g. you can create the typical ringmodulator sound from the fifties and sixties as used by e.g. Karl-Heinz Stockhausen or those SF-timbres from many sixties and seventies SF movies.

The gain controls on the A2 and B2 inputs are there to allow low level (line level) signals to be fed directly into the module and set the gain so they become the normal high level signals that go on in the modular system. One application would be to feed a signal into e.g the A1 input and the input of a stompbox effect. Then route the output of the stompbox into the A2 input and crank up the gain from the stompbox output (that is often at line level) till it matches the A1 input level and now crossfade between the dry sound and the wet stompbox effect, e.g controlled by an envelope or a sequencer. Alternatively it is also possible to use a fader to set e.g. echo time on a stompbox, in this case one sends the output of a fader to the input of an echo-box, and reconnect the output of the echo-box to the A2 input, with the audio signal to be processed on the A1 input, while listening to the fader output. When the fader is turned left the dry input signal will be present on the output. By turning the fader to the right the output signal that is also routed into the echo-box will now route back a delayed signal into input A2 and the delayed signal will also be rerouted into the echo-box and thus start to create echo repeats. When turned more and more to the right (and the gain level set correctly) this patch will eventually create an infinite repeat. And this is now under full voltage control.

It is good to note that when a signal is connected to only input A1 (or B1) and the output is taken only from AX/L out (or BX/L out) the input signal will go to both VCAs and the output will be taken from the mix of the VCAs. The gain on A2 and B2 now has an interesting feature, as when it is opened it will start to clip the input signal when a high level signals like from an Osc or the output of a filter is used. Now you can use the module as a distortion by letting the signal clip and basically set a mix between the clipped and the unclipped signal by the fader knob.

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