AM8102 SH02 VCF


Description The AM8102 module is faithful replica of the filter from the legendary Roland SH-2 that was released in 1979. The AM8102 is a fantastic sounding 4-pole low pass filter with that unmistakable Roland filter sound, in a narrow skiff friendly Eurorack module.

The original SH-2 uses four Rohm BA662 chips cascaded into a 24dB low pass filter. Roland first implemented this design in the large 700 Modular in the 703 filter using CA3080 chips. Variability in the offset of these chips required expensive trimmers, so Roland designed their own improved OTA chip with Rohm and used this in the 100M, SH-1, SH-2, SH-09 and Jupiter 4 before it was replaced by the IR3109 filter chip.

Each of the filter implementations across these synthesizers is slightly different, with the SH-2 using both a JFET buffer and the internal BA662 buffer on each filter stage. Roland switched to using Mylar filter capacitors rather than the smaller ceramic capacitors that they usually used.

Eurorack Module:    10HP wide
User Manual:              AM8102 User Manual

AM8102 Module

AMSynths Design The AM8102 module was the first module in the world to use Rpar AS622 chips in the filter core, to replace the originals BA662. The AM8102 includes buffering Op Amps to interface to Eurorack modular levels. The filter does not have Q compensation but the signal level does not decrease dramatically with higher Q settings. The resonance is smooth and controllable into self-oscillation, and the filter will oscillate from 10Hz to 20kHz.

There are slide potentiometers (with LED’s) for adjusting the Frequency Cutoff, and the frequency modulation from Keyboard, LFO and Envelope CV signals, There are rotary potentiometers for adjusting the mix between two audio inputs and the degree of resonance. There is a small slide switch to select whether the envelope CV input is Normal or Inverted.

The AM8102 is hand built with high quality components, including Wima polypropylene capacitors, Alpha potentiometers, and Eagle control knobs. The development of this iconic module identified a 40 year old error in the Roland SH-2 service notes – the filter capacitors are marked as 4,700pF (0.0047) but are actually 470pF.

There are six 3.5 mm jack sockets on the front panel:

  • 2x audio inputs
  • 3x frequency CV inputs
  • 1x audio output

Outcome & Availability The AM8102 VCF module completed development on 21st April 2022 and is in production. Check our webstore for more details and pricing.

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