ADDAC System 713 (2022–)

A stereo mixer that clips, howls, and gate-crushes your mix.

Overview

Plug in a clean stereo patch, turn up the master, and it looks like a polite little summing box. Push it and the ADDAC 713 shows its teeth. It's a fully discrete analog mixer inspired by the Moog CP3, built on rugged transistor stages that invite distortion instead of avoiding it. It was designed initially as a percussion mixer to place hits in the stereo field. ADDAC scrapped that idea and turned the 713 into a feedback, gate-generating, overdrive-happy mixer.

At its core, it’s a four-channel stereo mixer in 8HP—compact, yes, but deceptively deep. Three of those channels accept stereo inputs, each with individual gain and pan controls, letting you place sounds anywhere in the stereo image. The fourth channel is mono, a deliberate nod to tradition: keep your kick or bass dead center while everything else swirls around it. That alone makes it useful in any Eurorack system, but the 713 doesn’t stop at clean summing. It’s what happens after the mix that defines it. A feedback loop tucked under the third channel lets you route the master output back into the input, driving the entire mix into self-oscillation or cascading distortion. Turn the feedback knob clockwise and you don’t just get louder saturation—you get harmonic chaos, gate-like stuttering, and unpredictable textures that feel more like circuit bending than mixing.

Clipping is built in, not a switchable effect. The soft clipping switch engages an anti-click circuit with a built-in low-pass filter, with three positions: soft low pass, off, and hard low pass. In soft mode the highs are smoothed, giving warm, rounded saturation. Hard mode makes the low-pass kick in more aggressively, clamping down on the high-frequency fizz that can show up when the feedback path is driven hard. It keeps the 713 from turning into an unlistenable mess when pushed.

Two LEDs on the front panel monitor output level and clipping behavior. Unlike many modern mixers that aim for transparency, the 713 adds weight, grit, and a certain analog "breath" to anything that passes through it. Even at moderate levels there's a slight thickening of the signal, a gentle saturation that warms up cold digital oscillators. Feed it multiple overdriven oscillators or external drum machines and it stops being a mixer and starts being a performance instrument.

Specifications

Key Features

Discrete Analog Circuitry with Character

The 713 isn't built around op-amps or ICs. It's fully discrete, meaning each gain stage is made from individual transistors and passive components, much like the Moog CP3 that inspired it. That gives the module a dynamic, nonlinear response. When you turn up the gain, the signal blooms, with harmonics emerging in layers. The discrete topology also helps the module handle feedback without fizzling out or locking up. Instead it oscillates with a musicality that's hard to replicate digitally. Even at unity gain there's a slight coloration, a "body" that makes quiet patches feel fuller.

Feedback and Gate Generation

Few stereo mixers let you route the output back into the input. The 713 allows it and encourages it. The feedback knob is a performance control, not a trim. At low settings it adds a subtle doubling effect or light resonance. Turn it up and the mix begins to self-oscillate, making drones, metallic rings, or rhythmic pulses depending on the input material. Push it further and the feedback path starts to clip aggressively, producing gate-like chopping that slices your audio into stuttering fragments. This isn't clean amplitude modulation. It's chaotic, unpredictable, and deeply analog. Some users report that at extreme settings the feedback can generate its own rhythmic patterns, almost like a crude sequencer born from noise. It's not for every patch.

Smart Clipping and Output Shaping

The three-position soft clipping switch is one of the most thoughtful choices on the module. In "soft low pass" mode, a gentle filter rolls off the top end just before the output stage, reducing high-frequency harshness when driving the mixer hard. That helps with bright digital sources or FM oscillators that get shrill under distortion. In "off" mode the signal path is as direct as possible, so you hear the raw clipping character. "Hard low pass" engages a steeper filter, useful for taming feedback squeal or making lo-fi, telephone-style effects. The anti-click circuit, active in soft mode, prevents pops when patching or adjusting levels. Together with the dual clipping LEDs, this gives real-time feedback on signal behavior, so it's easier to ride the edge of breakup without going over.

Historical Context

The ADDAC 713 arrived in 2022, when Eurorack was deep into a "golden age" of utility modules: mixers, attenuators, and processors that were no longer afterthoughts but central to performance. Early modular systems relied on simple summing, and demand for stereo processing grew alongside live modular performance. The 713 offers not just summing but transformation. It's a descendant of the ADDAC 703, a mono discrete mixer that had already earned respect for its warmth and drive. By going stereo and adding feedback and gate functions, ADDAC did more than scale it up.

It also reflects a trend in Eurorack, the blurring of lines between signal path and effect. The 713, 712, and 714 from ADDAC are tone-shapers, distorters, and sound manglers as much as clean utilities. Competitors like Intellijel, Mutable Instruments, and ALM had already explored saturated mixers, but few offered the 713's combination of discrete design, feedback routing, and aggressive clipping in such a compact form. Its closest relative might be the Moog CP3, but the 713 pushes further into experimental territory and treats instability as a feature rather than a flaw.

Collectibility & Value

As of 2026, the ADDAC 713 remains in production and readily available, so it's not a "collector's item" in the traditional sense. It has still earned a cult following among modular performers who value character over cleanliness. The original price of €220 for the assembled version holds steady, with DIY kits available at a lower cost for those comfortable with surface-mount soldering. On the secondhand market, used units sell for €180 - €220 depending on condition, with little depreciation, which is rare for a utility module.

Failures are rare, but service technicians note that the feedback path can be sensitive to improper patching, especially if high-level signals are fed into the return. There are no known design flaws, but owners report that the module draws a relatively high 100mA on both rails, so users with power-limited cases should plan accordingly. The discrete circuitry is sturdy, but like all analog gear it can drift slightly over time. Recalibration is rarely needed, but checking input/output levels every few years is advisable for critical applications.

When buying used, check that the pan pots don't crackle and that the feedback knob responds smoothly across its range. The LEDs should illuminate with signal, and the soft clipping switch should click cleanly between positions. Because the 713 is often used in live sets, look for signs of overuse: worn knobs, loose jacks, or scratches on the panel that suggest heavy gigging. A well-maintained unit will last for years, but this isn't a "set and forget" module. It's meant to be pushed, so expect some wear on a battle-tested unit.

eBay Listings

ADDAC System ADDAC713 Stereo Mixer 3-Channel Pan Control Use

$490

ADDAC System ADDAC713 Stereo Discrete Mixer EURORACK - NEW -

$309

ADDAC ADDAC713 Stereo Discrete Mixer DIY Kit 3-Channel Pan C

$335

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