Name: Doepfer A-138e 3-Way Crossfader
SKU: 449291

Module A-138e is a versatile unit comprising four identical sub-units that can operate in various modes for signal processing:

Polariser: Utilizing only input A, it allows the original signal to pass through unaltered in the counter-clockwise (ccw) position, outputs an inverted signal in the clockwise (cw) position, and outputs no signal at the centre position.
Two-way Crossfader type 1: With signals at inputs A and C, and the switch to the left (input B open), it blends these two signals, providing equal mix at the centre position.
Two-way Attenuator: Signals are again connected to A and C, but with the switch to the right (input B grounded), it attenuates signal A from ccw to centre, and signal C from centre to cw, with no output at the center.
Three-way Crossfader: With signals at inputs A, B, and C, it crossfades between these signals: outputting only A at ccw, a mix of A and B from ccw to centre, only B at centre, a mix of B and C from centre to cw, and only C at cw.
Two-way Crossfader/Polariser type 2: With signals at inputs A and B, it outputs only A at ccw, a mix of A and B from ccw to centre, only B at centre, then a mix of B and the inverted A from centre to cw, and just the inverted A at cw. This is particularly useful for CV mixing, such as fading between an ADSR and an LFO.

The A-138e module also offers a separate output for the inverted signal of input A. Control is managed through potentiometers with a centre click and a middle terminal.

Sub-unit 4 can double as a mixer for the signals from units 1-3. To do this, you need to change an internal jumper: disconnect it from JP3 (the default position) and reattach it to JP2. Then, when you position sub-unit 4's switch to the left or adjust its control between points B and C, it will mix the outputs from units 1-3. Alternatively, you can hook up an A-138a/b mixer next to the A-138e for a combined output from all four sub-units, which requires a bit of soldering.