Doepfer A-127 VC Triple Resonance Filter Breakout Module

The Doepfer A-127 VC Triple Resonance Filter Breakout Module is the long-awaited expansion for the A-127, one of the oldest filter designs released by Doepfer. Thanks to the expander, you can access different filter-types with much more ease.

From September 2014 the A-127 Breakout Module is available. This expansion module offers these new functions:

additional notch filter for each sub-unit

separate outputs for lowpass, highpass, bandpass and notch for each sub-unit

separate audio input with attenuator for each sub-unit

The breakout module allows the separate use of each of the three A-127 filters. In addition the filters can be patched parallel or serial. Especially the serial connection of three notches generates very complex phasing-like structures. For parallel filter connection the existing mixer of the main module may be used or an external mixer. For serial connection the filters are patched in the desired sequence at the breakout module. A jumper is used to define the filter type for each sub-unit for the mix unit of the main module.

Remark: The breakout module can be used without modification only in combination with the new version of the A-127 (pcb printing "Version 4"). Only the new version has the expansion connector available, that is required to connect the breakout module. It's also possible to combine the breakout module with older versions of the A-127 (versions 1, 2 and 3) but in this case soldering is required to connect the breakout module to the main module (soldering 4 wires to each filter unit). We will publish corresponding modification instructions as soon as the breakout module will be available.

Instructions how to connect A-127BOM and A-127 main modulel: A127BOM.pdf