AM8112 SN-101 VCA & ADSR

Description This module is an accurate replica of the ADSR and VCA in the Roland SH-101 analog mono synth which was released in 1982.

EuroRack Module:   10HP wide
User Manual:            Download PDF

The VCA is based on the BA662 OTA chip (AS662 clone) with two audio inputs without any attenuation (INA, INB), and an audio output (VCA OUT) with a rotary volume control.

There are no external CV inputs, as the VCA is controlled by the on-board ADSR. A small slide switch selects how the VCA is controlled; HOLD sets the VCA to a constant maximum level, ENV selects the on-board ADSR, and GATE selects the external gate signal.

The original ADSR circuit is based on a dual Op Amp with transistor switches and is a different topology to the contemporary Roland 100M. It has the following specifications:

• Attack: 1.5ms to 8s
• Decay: 2ms to 10s
• Sustain: 0 to 100%
• Release: 2ms to 10s

The AMSynths circuit replicates the original ADSR with the attack maximum increased from 4 to 8 seconds. The ADSR is triggered by the GATE external input or by both GATE and TRIGGER if the trigger input is connected. There is a manual momentary push button which also triggers the ADSR, and a red LED indicates a gate signal is present.

The ADSR output is available on the ENV OUT jack socket, so that the envelope CV signal can be patched into a filter, such as the AMSynths AM8101.

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

• INA, INB - VCA audio inputs
• GATE - tradiational +5V gate signal for VCA and ADSR
• TRIG - +5V short trigger signal
• ENV OUT - Output of the ADSR
• VCA OUT - Ouput of the VCA

The module comes with a set of M3 mounting screws and washers, and a standard Doepfer power cable. Theere are soft red LED's in the sliders, set at a low level of illumination.

PRODUCT STATUS: IN PRODUCTION