AM8101 SH-101 VCF


AM8101 Module

Overview  This module is replica of the low pass VCF from the legendary Roland SH-101 which was launched in November 1982 and became one of Roland’s most popular analog synths with 8,000 sold over 5 years. In 2022 Alfa Rpar released the AS3109 in SMD, a clone of the IR3109 filter chip which is at the heart of the SH-101 filter. This new chip enabled me to restart production of the Jupiter 6 and 8 filters but also add a new module – the AM8101.

This is a warm sounding filter with smooth frequency control and a resonance that gradually increases up to full self oscillation, a sound very reminiscent of the early 1980′s. The filter is a simplified version of the Jupiter 8 implementation, with a single mode (24dB) and no Q compensation or High Pass Filter.

Euro Rack Module:   10HP wide
User Manual:            Download PDF
Project Notes:           Download PDF

SH-101 VCF PCB

Detailed Description This module is an accurate reproduction of the SH-101 low pass voltage controlled filter, using an AS3109 OTA chip in the filter core. The design has been updated to use modern components (such as the OTA capacitors and high quality Op Amps). The resonance is smooth and goes into controllable self-oscillation.

There are two front panel slider potentiometers for adjusting the Cutoff Frequency and Resonance, with red LED illumination. There are rotary potentiometers for 2x control voltages (MOD and ENV) and 2x audio signal inputs (INA, INB), they have Roland TR808 style knobs.  The ENV control voltage can be inverted with a slide switch, and there is a 1V/octave keyboard input (KYBD), which is directly connected to the filter.

Potentiometers:

  • Cutoff Frequency
  • Resonance
  • MOD, ENV
  • INA, INB

Connections [3.5mm jack]:

  • INA, INB audio inputs
  • KYBD, MOD, ENV CV inputs
  • OUTPUT

Outcomes & Availability The AM8101 was designed in early March 2022 using the new AS3109 chip. It was released onto the market with a red aluminum panel in May 2022. Check the webstore for the module, panels, PCB’s and Hard to Find Kit.

 

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