ADDAC System ADDAC804 Audio Integrator (2010s?)
Plug your iPhone into your modular rig and turn your apps into synth modules—yes, really.
Overview
The ADDAC804 Audio Integrator isn’t your typical Eurorack voice or filter—it’s a bridge. A literal audio passport between the touchscreen world of iOS and the patchable, cable-snaking universe of modular synthesis. At a time when iPhones and iPads were becoming serious tools for sound design, ADDAC System saw an opportunity: why treat mobile apps as isolated islands when they could be full citizens in a modular setup? That’s where the 804 comes in. It lets you send audio from your modular system into an iOS device—say, to run a signal through a granular app—and then bring it back out again, all in real time, with no extra gear. But it doesn’t stop at audio I/O. The module also extracts envelope followers from whatever iOS app is making sound, giving you two voltage-controllable triggers with adjustable sensitivity and decay. That means the amplitude of your iPad synth can fire off envelopes in your rack, opening up feedback loops and hybrid workflows that feel ahead of their time.
It ships with a custom iOS duplex audio cable—the kind that works with the extended headphone jack protocol Apple used before the Lightning era—so you’re not left hunting for obscure adapters. And while it only draws 20 mA from the +12V rail, it plays nice with both ±12V and ±15V power systems, making it a plug-and-play fit for nearly any case. At just 8 HP wide and 15 mm deep, it’s also svelte enough to tuck into even the most crowded skiff. This isn’t a sound generator, and it won’t filter or modulate your signal in the traditional sense. But as a utility, it’s quietly revolutionary—turning your iOS device into a kind of chameleon module, capable of being whatever app you load into it.
Specifications
| Manufacturer | ADDAC System |
| Format | Eurorack |
| Width | 8 HP |
| Depth | 15 mm |
| Current Draw | 20 mA +12V |
| Power compatibility | compatible with ±12v and ±15v power supplies |
| Bus board cable | 8 × 2 idc (doepfer style) connector |
| Features | 2 independent inputs, 2 independent volume knobs, 2 independent outputs, 2 independent envelope knobs to set trigger levels, 2 envelope decay knobs |
| Included accessory | ios duplex audio cable included |
Key Features
Two-way audio integration with iOS
The core idea is simple but powerful: send audio from your modular synth into an iOS device, process it in any app—think Moog Model 15, GarageBand, or even a field recording tool—and then return the processed signal back into your rack. The ADDAC804 handles this bidirectional flow with two independent input/output pairs. On the output side (sending to iOS), you’ve got two volume-controlled signals that feed into the iOS device via the included duplex cable. On the input side (receiving from iOS), two separate audio outputs bring the iOS signal back into your modular system, ready to be mixed, filtered, or further processed.
Envelope followers with full control
Beyond just shuttling audio, the 804 listens. It analyzes the incoming iOS audio and generates control voltages using two envelope followers. Each has its own level knob to set the trigger threshold—handy when dealing with apps that output at wildly different volumes—and a decay knob to shape how long the envelope lingers. These CV outputs can trigger envelopes, gates, or sequencers in your rack, letting the dynamics of your iPad synth drive physical modules. It’s a feedback-friendly design: you could, for example, use an iOS granular app to generate texture, extract an envelope from it, and use that to modulate a filter on a hardware synth—all without leaving the patch.
Built-in iOS connectivity
One of the biggest headaches in integrating mobile devices into modular setups is cabling. The ADDAC804 sidesteps that by including a dedicated iOS duplex audio cable. This isn’t a standard headphone cable—it’s wired for simultaneous input and output through the advanced audio jack found on iPhones and iPads of the era (pre-Lightning, and not compatible with the iPhone VS1, as noted in the design docs). That means no additional adapters or USB interfaces. Plug in, patch up, and go. The module essentially acts as a dedicated audio interface for your iOS device, but in Eurorack format.
Historical Context
The ADDAC804 emerged during a surge of interest in mobile music-making, when iOS devices became capable platforms for serious audio applications. Rather than treat these devices as standalone tools, ADDAC System positioned the 804 as a way to dissolve the boundary between app-based and hardware synthesis. It’s part of the ADDAC800 series, a line focused on bridging external gear with modular systems. While the exact release year isn’t documented in the available sources, its design philosophy aligns with the early to mid-2010s, when Eurorack was expanding beyond traditional synthesis into hybrid and experimental workflows. It wasn’t just about adding another oscillator—it was about redefining what a module could be.
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