Doepfer A-138c Polarizing Mixer

The Doepfer A-138c Polarizing Mixer is a special tool with multiple purposes. Signals cannot just be mixed in different portions, but you can also dial in "mirror images", that is, inverted version of the input signals by the built-in polarizers. This way you can add and subtract voltages in a mix. This mixer, as every tool with polarizer, brings new dimensionality into your patches. Don't forget the handy DC voltage source on channel 1 when nothing is plugged to the input!

The Doepfer A-138c Polarizing Mixer is a four channel mixer, that allows to add or to subtract four incoming voltages to the output signal. In the middle position of the corresponding control the amplification is zero. Turning the knob counterclockwise the signal is subtracted from the output sum with increasing amount. Turning the knob clockwise the signal is added to the output sum with increasing amount. The output control works in the same way, i.e. the resulting output signal can be additionally attenuated and/or inverted.

The module is used in the first place to mix control voltages (e.g. ADSR, LFO). It can be used to mix audio signals too but there is no difference between adding and subtracting audio signals unless they have a fixed phase relationship (e.g. the outputs of a VCO, or the input and output signal of a VCF). For audio signals without phase correlation there is no difference between addition and subtraction. Control In1 works as a DC offset generator (about -5V...+5V) provided that no patch cord is plugged into socket In1. If this feature is not required it can be deactivated by removing a jumper on the pc board. The voltage controlled version of a polarizer is the module A-133. For more detailed information please look at the English user's manual