ADDAC System ADDAC801 (2011)
A no-frills, 4HP mixer that does what you need and nothing more.
Overview
The ADDAC801 Simple Mixer has three input channels, each with its own attenuator knob. They feed a single standard output and an inverted output. It handles both audio and control voltages, so it works for summing LFOs as well as layering oscillators. It doesn't morph, modulate or memorize. The whole thing fits in 4 HP, which is handy when the rack gets crowded.
There are no trim pots, no switches and no hidden modes. Just knobs, inputs and outputs. It doesn't promise color or character, so what you get is a clean mix. The inverted output flips a signal's polarity on the fly, which is useful for subtractive mixing or for creating interesting CV inversions.
Specifications
| Manufacturer | ADDAC System |
| Model | ADDAC801 simple mixer |
| Format | Eurorack Module |
| Dimensions | 4 HP, 25 mm deep |
| Current Draw | 20 mA +12V, ? mA -12V, ? mA 5V |
| Channels | 3 channels mixer + inverted out |
| Function | 3 Channel Audio/CV Mixer |
| Controls | 1 Attenuator Knob per Channel |
| Outputs | 1 standard output, 1 inverted output |
Historical Context
The ADDAC801 was mentioned in a post on Matrixsynth on January 8, 2011, as being available for pre-order. That was its debut into the Eurorack ecosystem, at a time when the format was gaining serious momentum among DIY and boutique builders. It belongs to the ADDAC800-series and is now listed under the "ADDAC Legacy Modules" on the manufacturer's website, which suggests it's no longer in production. It didn't reinvent the mixer category. It arrived when compact, affordable utility modules were in high demand, alongside other minimal 4HP designs from builders like Invy and STG.
Collectibility & Value
The ADDAC801 currently lists at $149 on Reverb, down from its original listed price of $185. Given its utility-first design and legacy status, it's likely to appeal more to practical Eurorack users than to collectors hunting for rare or sonically distinctive gear. There's no public data on common failures or repair needs, but the lack of complex circuitry suggests reliability isn't a major concern. As with any discontinued module, availability depends on secondhand turnover.
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