ADDAC System ADDAC107 Acid
The ADDAC107 Acid is a compact 9HP Eurorack synth voice from Portuguese maker ADDAC System. It puts a VCO, VCF and VCA in one module. It sells new for around $175. Listings also show up at £195.99 and roughly $277 on the used market.
The module started out as something else. According to ADDAC's own product copy, the company set out to design a complex drum source. Somewhere along the way it became clear the circuit worked far better as a synth voice, a "lucky accident" that ADDAC kept. It suits acid-style music, distorted leads and basslines.
The VCO has Frequency and Fine Tune knobs, plus a dedicated CV input with an attenuator, and it tunes over four octaves. A faceplate switch selects triangle or saw. ADDAC encourages pushing the filter into high resonance or self-oscillation, and driving the VCA into saturation, for extra harmonics. The manual (revised June 2023) covers normaled/self-patched routing. It also includes an assembly guide with soldering steps for the small PCB and slider switch.
Documentation is otherwise thin. The available research captured no detailed specs on filter type or input/output counts, and the only power figure is 80mA on both the +12V and -12V rails. Production years aren't recorded. One user rated the manual 9.1 out of 10 on manua.ls.
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