ADDAC 301 (2014–present)

Name: ADDAC System 301
Brand: ADDAC System

Four HP module that takes your old expression pedal, frees your hands, and keeps cables out of your mouth mid-performance.

Overview

Picture the tangle. Patch cables knotted around your forearm, one hand twisted behind your back reaching for a hidden attenuator, the other fighting a sequencer that won't sync, and your foot tapping the floor doing nothing. Then you remember the dusty expression pedal at the bottom of your gear case, the one you used with your old keyboard rig back in 2008. That's what the ADDAC 301 is for. It's a small, red, 4 HP module that doesn't make sound and doesn't generate sequences. It gives your feet a voice in the modular.

Launched in early 2014 as part of ADDAC's 300 Series of expressive control modules, the 301 Floor Control was built for one purpose: letting you use standard expression and sustain pedals in a Eurorack system without fuss. Most expression solutions need voltage scaling, offset adjustments, or external power supplies just to get a pedal to sweep a filter smoothly. The 301 does it all in one compact module, with knobs, LED feedback, and a +5V bus board adaptor that doubles as a small utility fix for power-starved skiffs. No MIDI, no digital processing, no hidden modes. It's a clean, analog-friendly interface.

The 301 is a utility controller rather than a sound module. It sits below ADDAC's more complex offerings like the 303 Muscle Sensing or the 714 Vintage Clip. The 301B Dual Expression Attenuator and 301C Dual Sustain Switcher are passive alternatives. The 301 is the only one in the series with active CV processing, LED monitoring, and offset/range control, which makes it the centerpiece of ADDAC's expressive control lineup. It's often the first module to reach for when you want real-time, hands-free modulation.

Specifications

Manufacturer	ADDAC System
Production Years	2014–present
Original Price	€70
Width	4 HP
Depth	40 mm (4 cm)
Current Draw	20 mA (+12V), 0 mA (-12V), 0 mA (+5V)
Bus Board Cable	8 × 2 IDC (Doepfer style)
Expression Pedal Input	6.3 mm (1/4") stereo jack
CV Output Range	Adjustable from -10 V to +10 V
Offset Control Range	±5 V
Sustain Pedal Input	6.3 mm (1/4") mono jack
Gate Output	1 V to 10 V (normalized to +10 V)
CV Outputs	Positive and inverted
LED Indicators	CV positive, CV negative, gate output
+5V Bus Board Adaptor	Yes (jumper-removable)
Compatibility	Standard stereo expression pedals (e.g., Moog EP-2, Behringer FCV100); mono expression pedals require modification

Key Features

Expression Control with Precision

The heart of the 301 is its expression pedal input, which accepts any standard stereo 1/4" expression pedal—no adapters, no soldering (unless you’re using a mono pedal, which requires a simple mod). What sets it apart is the pair of front-panel knobs: Range and Offset. The Range knob lets you scale the full travel of your pedal from a narrow ±1 V sweep to the full Eurorack ±10 V range. This is critical—some modules respond dramatically to small CV changes, while others need a full 10 V to open up. Being able to dial in the exact range means you can go from subtle filter nudges to full-on oscillator sweeps without overshooting. The Offset knob then shifts that entire range up or down by ±5 V, so you can start a sweep from zero, or bias it into positive territory for exponential responses. It’s rare to find this level of control in such a small module, and rarer still for it to be this intuitive.

Visual Feedback That Actually Helps

Two small LEDs, labeled "+" and "-", track the polarity of the CV output in real time. When your pedal sweeps into positive voltage, the "+" LED glows. When it dips negative, the "-" lights up. If you're modulating a VCA and the sound cuts out at the heel position, a quick glance tells you whether you've dipped into negative voltage where the VCA won't respond. The gate output for the sustain pedal has its own LED too, so you can see whether the pedal is registering as "on" or "off." In a dark studio or on a dimly lit stage, that helps.

Hidden Power Utility: The +5V Adaptor

On the back of the module is a jumper that enables a +5V bus board adaptor. When it's activated, the 301 can supply +5V power to any compatible bus board. That's especially useful in skiff setups where the main power supply might not include +5V rails. It addressed a real gap in early Eurorack power distribution, where many modules, especially digital ones, began requiring +5V but not all power systems provided it. Newer power solutions have largely caught up, but the feature still makes the 301 a handy upgrade for older or minimalist cases. The jumper can be disabled, so you aren't forcing +5V where it's not needed.

Historical Context

The ADDAC 301 arrived in 2014, right as Eurorack was shifting from niche hobbyist curiosity to mainstream modular adoption. Many players were coming from traditional keyboard rigs, bringing expression pedals they didn't know how to use in modular. Most solutions were DIY builds, clunky external converters, or expensive MIDI-to-CV boxes. The 301 filled that gap with a Eurorack-native answer. It wasn't the first foot controller for modular - Intellijel's Touché and Livewire's Variable Mu had already explored expressive control - but it was among the first to make it accessible, affordable, and rack-efficient.

ADDAC, based in Lisbon, had already built a reputation for musician-first design with modules like the 008 Quad LFO and the 101 Digital Noise Generator. The 300 Series, including the 301, was a deliberate pivot toward performance and tactile control. Competitors like Doepfer and Analogue Solutions offered basic pedal inputs, but few provided the same level of voltage control and feedback.

Collectibility & Value

The ADDAC 301 has never been a "hype" module, but it's become a staple. It's not rare - production has remained steady since 2014 - and it's not discontinued, so there's no artificial scarcity. On the used market, prices range from $75 to $110 depending on condition and region. Units in full working order with clean jacks and responsive knobs typically sell in the $85 - $95 range, while those with worn labels or stiff potentiometers go for less. It's a passive interface with minimal internal circuitry, so failure rates are low. The most common issues come from the input jacks, especially if users frequently plug and unplug pedals. Oxidation or loose solder joints can cause intermittent signal, so check both expression and sustain inputs before buying.

The +5V adaptor feature can cut both ways. If the jumper is left enabled in a system that already supplies +5V, it can cause power conflicts or even damage sensitive modules. Service technicians observe that many users aren't aware of the jumper's function, so verify its position when buying used. Otherwise, maintenance is minimal: no firmware, no moving parts beyond the knobs, and no calibration needed. The only real wear point is the expression pedal jack, which sees the most use. Cleaning with contact cleaner and gentle reseating of cables usually resolves most issues.

For a performance-oriented rack, the 301 is a no-brainer. For players coming from hardware synths or DAWs, it lets you use your feet the way you would on a piano or guitar rig. It's also one of the few ADDAC modules that hasn't appreciated significantly in price, which makes it an accessible entry point into the brand.