doepfer a-138e quad three-way crossfader / mixer / polarizer price : $140.00

module a-138e contains four identical units that can be used for different crossfading, mixing and polarizing applications:

polarizer: only input a is used, inputs b and c are unconnected. in this case the sub-unit works as a polarizer. in the ccw position of the control the signal connected to input a appears at the output, in the cw position the inverted signal, in the center position no signal appears at the output

two-way crossfader type 1: two different signals are connected to the inputs a and c, switch is in the left position (switching contact of input b is open). in this case the sub-unit works as two-way crossfader between the two signals connected to the inputs a and c. in the center position both signals appear with the same level.



two-way attenuator: two different signals are connected to the inputs a and c, switch is in the right position (switching contact of input b is connected to gnd). in this case control is used to attenuate signal a (between ccw and center position) or signal c (between center and cw position). in the center position no signal appears at the output. similar to the two-way crossfader but without signal in the center position.

three-way crossfader: three different signals are connected to the inputs a, b and c. in this case the sub-unit works as three-way crossfader. in the ccw position only signal a appears at the output. between ccw and center position a mix of the signals a and b appears at the output. in the center position only signal b appears at the output. between center and cw position a mix of signals b and c appears at the output. in the cw position only signal c appears at the output.

two-way crossfader/polarizer type 2: two different signals are connected to the inputs a and b. in the ccw position only signal a appears at the output. between ccw and center position a mix of the signals a and b appears at the output. in the center position only signal b appears at the output. between center and cw position a mix of signals b and inverted signal a appears at the output. in the cw position only the inverted signal a appears at the output. useful for cv mixing: e.g. signal a = adsr, signal b = lfo. in this case one can fade between adsr ... lfo + adsr ... lfo ... lfo - adsr ... - adsr.

in addition the inverted signal of input a is available as a separate output. potentiometers with center detent and center terminal are used as controls.

sub-unit 4 can be used optionally as a summing unit for the devices 1-3. for that an internal jumper is available that connects the outputs 1-3 to unit 4. alternatively an a-138a/b mounted next to the a-138e can be used as summing unit for all four sub-units (2 wires have to be soldered to the a-138a/b).



applications:
attenuation of audio and control voltage signals
polarizing of audio and control voltage signals
two-way crossfading of audio and control voltage signals
three-way crossfading of audio and control voltage signals
two-way crossfading and polarizing of audio and control voltage signals
changing filter characteristics (e.g. lowpass to highpass)



this module has a maximum current draw of 10ma. it requires 16 hp/te worth of space to fit in a eurorack frame.