ADDAC 807C (2017–)

When a Eurorack system outgrows five stereo channels, this is how to add more without losing CV control of any of them.

Overview

You know that moment when your modular rig starts feeling cramped, like you're trying to mix a full band through a pocket mixer? That’s where the ADDAC 807C steps in—not with a compromise, but with a full architectural expansion. It’s not a standalone mixer. It’s not even the main event. The 807C is the four-channel stereo growth pack for the ADDAC807A/B VC Stereo Summing Mixer system, turning a formidable console into a near-studio-grade modular hub. And it doesn’t just add channels—it brings them in with full CV control, LED metering, pan automation, and send/return routing that makes you wonder why every mixer doesn’t work this way. This isn’t a utility add-on; it’s a statement that Eurorack can scale with grace, without sacrificing hands-on control or sonic integrity.

The 807C adds four more stereo channels that copy the flagship's layout. Each has volume and pan knobs, attenuverters, send controls, mute buttons, pre/post switching, and phase and synth/line toggles. The ADDAC807 system was designed to feel like a high-end analog console, and the 807C keeps that design intact.

And yes, it’s expensive. But you’re not paying for plastic knobs or half-baked features. You’re paying for a meticulously laid-out front panel, discrete analog signal paths, and a modular integration so deep it feels orchestral. The 807C doesn’t just let you add more voices—it lets you shape them dynamically, with CV inputs for volume and pan on every channel, so your mix can evolve over time like a living arrangement. It’s the difference between recording a band and conducting one.

Specifications

Manufacturer	ADDAC System
Production Years	2017–
Original Price	€620
Format	Eurorack
Width	38 HP
Depth	4.5 cm
Weight	0.6 kg (1.3 lb)
Max Current	250mA on +12V rail
Max Current	250mA on -12V rail
Power Supply Compatibility	±12V and ±15V
Bus Board Connector	8×2 IDC (Doepfer style)
Channels	4 stereo
Per Channel Volume Control	Knob with LED level indication
Per Channel Pan Control	Knob with L/R LED indication
Pan CV Input	±5V
Volume CV Input	±5V
Send Controls	Three sends per channel (Send 1, 2, 3) with Pre/Post and Mono Pre/Post switches
Mute	Per channel mute button
Cue/Mix Switch	Per channel
Phase Switch	Per channel
Synth/Line Switch	Per channel
Inputs	Stereo Input (Line level), Left Input, Right Input per channel
Outputs	Mono Output per channel

Key Features

Seamless System Integration

The 807C is a subsystem, not a module to drop into a case on its own. It works exclusively with the ADDAC807A (main control module) and 807B (I/O breakout), and the full console spans 118 HP when fully expanded. The 807C's channels feed directly into the master mix, cue bus, and matrix routing, so every new input behaves the same as the original five. No re-patching, no signal degradation. The 807B handles all the jacks and CV inputs, which leaves the 807C to do nothing but control.

Professional-Grade Channel Strip

Each of the four stereo channels on the 807C is a fully-featured strip: volume and pan with LED feedback, send routing to any of three stereo buses, pre/post toggles, mute, and even phase inversion. The synth/line switch lets you adapt to different signal sources, and the mono pre/post option gives you flexibility in effects routing. The attenuverters on volume and pan mean you can invert or scale CV control—say, panning left when your LFO goes positive, or fading in reverse. These aren’t just controls; they’re performance tools. And because the signal path is entirely analog and discrete, there’s no digital conversion or latency to muddy the tone. What you put in is what you get out—just louder, richer, and more organized.

CV-Driven Mixing as Performance

Every channel's volume and pan has a CV input, normalized to ±5V. Envelopes, LFOs, sequencers, or random sources can all automate the mix. A stereo pad can slowly widen as it fades in, or a drum loop can pan in a circle with each bar. The sends are CV-controlled too, so levels going to external effects can move. The main 807A also has a matrix mixer with its own CV inputs, so automation can be layered across several dimensions.

Historical Context

The ADDAC807 system launched in 2017. Modular synthesis already had plenty of complex utility modules by then, but few companies treated the mixer as a centerpiece. Most Eurorack mixers were compact and stripped down. ADDAC designed the 807A/B as a full console, borrowing from high-end studio gear. The 807C was the next step, a way to scale it up. Other manufacturers were adding digital control or MIDI integration to manage complexity at the time. ADDAC stayed with analog signal paths and tactile control.

Competitors like WMD's Performance Mixer offered some automation, but none matched the 807's depth of integration or the split between control (807A) and I/O (807B). The 807C let the system expand without adding clutter. The price kept it niche, but for those who needed it, there was no substitute.

Collectibility & Value

The ADDAC 807C isn't common on the used market, and when it does appear, it's usually part of a full 807A/B/C setup. Individual units sell for between $550 and $750, depending on condition and region. It's a specialized expansion, so it rarely trades alone. Buyers are typically completing a system they already own.

There are no known chronic failure points. The module uses standard jacks, high-quality potentiometers, and a solid PCB layout. Owners report long-term reliability, helped by the fact that the 807C has no active audio processing, only level control and routing. The biggest risk is logistical. Without the 807A and 807B, the 807C is useless. ADDAC doesn't sell the full system as a pre-built unit, so sourcing all three modules can take time.

Before buying, verify that the seller has all three modules (A, B, and C) if you’re aiming for the full 9-channel setup. Check for bent pins on the power connector and test all knobs for smooth operation. LED indicators should respond to signal levels, and CV inputs should track accurately. Given the cost, it’s worth asking for a demo video—especially since the real value of the 807C is in how it integrates, not just how it looks.