ADDAC300 Series ()

When your feet, muscles, or motors need to talk to your modular, this is how they do it.

Overview

The ADDAC300 Series isn't about oscillators, filters, or envelopes. It's about control - the kind that doesn't come from a keyboard or sequencer, but from your body, your pedals, or even a tiny motor turning a knob while you watch. Made by ADDAC System, these Eurorack modules fall under the banner of "300's Expressive Controls," a lineup dedicated to expanding how you interact with your synth. They aren't sound generators. They translate physical gestures into voltages, movements into modulation, tension into triggers. If your hands are already full patching, twisting, or playing, the ADDAC300 Series gives the rest of you something to do.

This family of modules is built for the tactile, performative, slightly theatrical side of modular synthesis. They read the flex of a muscle, the press of a foot, or the slow sweep of a servo-driven knob, and they work in real time. They're not essential the way a VCO is, but they're hard to forget in a live set. They share a series name and design philosophy, but each module does a very different job - from the utilitarian (dual attenuators and switchers) to the experimental (muscle sensing) to the mischievous (power starvation).

Specifications

Key Features

ADDAC301 & Floor Control: Feet on the Controls

The ADDAC301 and its sibling the ADDAC301 Floor Control are essentially the same idea - a Eurorack module that lets you plug in standard sustain and TRS expression pedals. The concept is simple, and the details are well thought out. Range and Offset knobs fine-tune the expression pedal's action. Range sets the voltage span from -10V to +10V, and Offset shifts that entire range up or down by ±5V. So you can map a pedal's travel to exactly the CV range you need, whether that's sweeping a filter from 3V to 7V or modulating an LFO from -5V to 0V. Two LEDs show the positive and inverted CV outputs in real time, and the sustain input generates a gate signal, also LED-monitored. It also includes a +5V bus board adaptor, with a jumper on the back to enable it, for systems that need that rail.

ADDAC301B & 301C: Passive Simplicity

The ADDAC301B Dual Expression Attenuator and ADDAC301C Dual Sustain Switcher are passive modules. They don't draw current from the power rail - just patch cables and physical control. The 301B takes any CV or audio signal and attenuates the level with an expression pedal. An invert switch lets the pedal decrease the signal instead of increasing it. The 301C does the same for on/off control: plug in a clock or audio source, stomp the pedal, and you've got a switchable gate or mute. They're just 3 cm deep and 4 HP wide, so adding foot control costs no power and very little space.

ADDAC303 Muscle Sensing: Control From Within

This is where things get weird. The ADDAC303 Muscle Sensing module uses electrodes (included) to detect muscle tension, turning flexes and twitches into control voltages. The Gain knob adjusts the output range (±10V), and Offset sets the baseline (±10V). A Smooth switch chooses between hard and soft smoothing of the raw signal, which helps tame jittery readings. It outputs both a positive and inverted CV, plus a comparator gate with an adjustable threshold, so you can trigger events when muscle activity crosses a certain level. As one forum user put it, "Mmmm, muscle sensing. Wire me up." It's about as direct a link between body and synth as you can get.

ADDAC306 VC Transitions: Five Channels of Morphing CV

The ADDAC306 VC Transitions is a five-channel CV generator that morphs between voltage states in multiple directions. Each channel has MINIMUM, SPAN, and DIRECTION controls, plus a common CV input and a shared TRANSITION CONTROLLER slider. Jumpers on the back set each channel's max range to either 5V or 10V. The CV inputs accept up to +5V, and outputs are jumper-selectable between +5V or +10V. Only positive voltages come out, which suits parameters that don't need bipolar modulation. Think slow sweeps across filter cutoffs, wavefolds, or panning, all driven by a single control voltage.

ADDAC300 REV.02: Starve It to Make It Sing

Power starvation isn't new. It's a staple of circuit bending, where reducing voltage to an analog module can make it "cough, choke, go spastic," as ADDAC puts it. The ADDAC300 REV.02 turns that hack into a safe, controllable module. It takes +12V from your power rail and uses a DC-DC converter to generate a bipolar 15V supply, which then passes through variable analog voltage regulators. The output voltage can be adjusted from 2.5V to 13.5V, with up to ±200mA available. The module itself can draw up to 600mA on the +12V rail, depending on the load. It includes short-circuit and overcurrent protection, so you won't fry your synth trying to make it scream. It's not for modules that need stable power.

ADDAC320 Servo Control: Motorized Knob Twisting

The ADDAC320 Servo Control, inspired by Neil Young's Whizzer, uses a 270-degree servo motor to physically turn a knob on another module. A microcontroller reads incoming CV (0 to +5V) and converts it linearly to motor position. A spring wire and metal couplers connect the motor shaft to the target knob. Two front-panel knobs, MIN ANGLE and MAX ANGLE, define the "sweet spot" of travel, so the knob doesn't spin past its useful range. If you raise MIN above MAX, the motion inverts. It automates a parameter without patching a CV - just set it and watch the knob turn. Replacement servos are available for 6€ each, plus VAT, so a burned-out servo is no big loss.

Historical Context

The ADDAC300 Series came out of practical needs and some playful experimenting. The ADDAC301 was born while the company was developing VC Stompboxes and testing expression pedals. They realized feet were often free during modular performances, and expression pedals were common, so they brought that control into the rack. The ADDAC320 Servo Control takes its cue from the "geniality" of Neil Young's Whizzer, a motorized device that tweaks guitar effects mid-performance. The ADDAC303 Muscle Sensing module was framed as introducing a "totally new interaction principle." All of these modules are grouped under the "300's Expressive Controls" category.

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