ADDAC System ADDAC216 Sum & Difference
The ADDAC216 Sum & Difference is a Eurorack utility module from ADDAC System's 200 Series. It was sold as a DIY kit (product code KITAD216EURO01) and as a pre-built module. It's an odd sort of mixer. It sums two input signals (X & Y), but each of its two independent sections can also subtract one from the other. The front panel is split into two equal sections, labeled A and B. Each has two inputs with gain attenuverters, an amplitude attenuverter, a bipolar offset, and switches for Absolute/Bipolar and AC/DC coupling. Each section gives you a normal output and an inverted output.
There's also an "Average mix output of both sections," which combines the results of the two sections. The panel has section A monitor LEDs. The module installs in a Eurorack system powered by ±12V and +5V. A black faceplate was standard at the time of the product listing. ADDAC offered custom panel colors (Red, Green, Blue, White, Silver Gray, Yellowed Silver, and Dark or Light Bronze) at an additional cost, with a 4-to-6 week lead time. Retail prices in period listings ran from roughly $148 to $185, depending on configuration and vendor.
Documentation is thin. No production years, original price with a specific year, dimensions, or power specifications are recorded. Everything known traces back to a single retailer listing and the user's guide PDF. No independent reviews or broader market context have surfaced.
- Two independent sections (A and B)
- Per section: 2 inputs with gain attenuverters, amplitude attenuverter, bipolar offset
- Absolute/Bipolar and AC/DC switches per section
- Output and inverted output per section
- Average mix output of both sections
- Eurorack format, ±12V and +5V power
- Available as DIY kit (KITAD216EURO01) or pre-built
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