AM8123 VCF, VCA & VC Pan (100M)

Overview The AM8123 is a re-imagined Roland 100M 120 module, a prototype 24dB VCF & VCA that Roland conceived in 1978. We have used an OTA 24dB low pass filter, a VCA with linear voltage control and added a stereo panning circuit.

EuroRack Module: 16HP wide
User Manual:           AM8123 User Manual

Module Description  The AM8123 use the AS3372 chip to provide a 24dB OTA based low pass filter with in built Q compensation. The VCF output and two external signals are mixed into a voltage controlled VCA and then optionally into two further VCA’s which provide voltage controlled panning. The VCF and VCA outputs are available along with left and right outputs.

The module is 16HP wide and has two PCB’s. The front PCB holds the jack sockets and potentiometers, with SMD Op Amps providing input signal and CV mixing. The main PCB has the combined  24 pin VCF and VCA chip. The PCB is 79mm wide and contains a lot of circuits, so 1/8W THD resistors have been used in some places. The output of the VCF is normalised into the first signal input of the VCA.

The physical design is similar to the Behringer System 100 in terms of layout and the use of trimmers for signal and CV adjustment. LED slide potentiometers are used for the primary filter controls (FREQ, RESONANCE, RES CV) and rotary controls are used for the VCA GAIN and PAN.

Front Panel The AM8123 has a powder coated front panel with white silk screen printing. The basic panel and holes was drawn with Front Panel Designer and exported as a DXF file. This was then imported into Illustrator and used as a background layer to position and draw the lettering. The finished drawing was exported as a 300 dpi PDF and sent for manufacturing along with the DXF file and the choice of panel colour (Pantone Mid Grey 5U).

Module Outcome & Availability  The AM8123 was developed in the spring of 2023 and production modules with grey powder coated panels will be available in mid 2023.




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