ADDAC 301 Floor Control (2013–2020)

A modest 4HP doorway to physical expression in modular—until you realize it’s secretly powering half your case.

Overview

It’s easy to overlook a module that doesn’t generate sound, shape it, or even trigger it—just sits there, quietly bridging your feet to the chaos. But the ADDAC 301 Floor Control is one of those unassuming modules that, once installed, you wonder how you ever played without. Designed for Eurorack systems where hands are perpetually tangled in patch cables and knobs, it hands control back to your feet: one stomp for sustain, one sweep of the heel-toe for real-time expression. It doesn’t make noise, but it makes everything else feel more alive. And then there’s the twist—buried in its back end, it can supply +5V to your bus board, turning it into a stealth power node for modules that need that elusive third rail. It’s not flashy, but in a system where every volt and HP counts, that little perk can be the difference between a clean build and a rat’s nest of adapters.

Originally released in 2013 as part of ADDAC’s 300 Series of interface modules, the 301 arrived at a time when Eurorack was shifting from academic curiosity to live-performance instrument. Musicians were no longer just tweaking patches in the studio—they were taking modular on stage, and suddenly, pedal integration wasn’t a luxury, it was a necessity. The 301 answered that need with surgical simplicity: two inputs (expression and sustain), two outputs (CV and gate), and a pair of trim controls that let you map the expression pedal’s throw exactly where you needed it. No menus, no firmware, no OLED screens—just knobs, jacks, and LEDs that blink in time with your footfalls.

It wasn’t the first pedal interface for Eurorack, but it was among the first to balance utility, precision, and expandability. While competitors offered basic gate triggers or fixed-voltage expression inputs, the 301 let you adjust the CV range from ±10V and add an offset of ±5V, meaning you could map a pedal sweep from 0V to 5V for filter cutoff, or -3V to +3V for vibrato depth, or even invert the response for reverse sweeps. The dual-color LEDs (positive and negative) give immediate visual feedback, crucial when you’re onstage under lights and can’t see your scope. And because it uses a standard 6.3mm stereo jack for the expression pedal, it works with nearly any off-the-shelf controller—Behringer FCV100, Moog EP-2, even Line 6 pedals if you’re willing to mod the cable.

But the real sleeper feature is the +5V bus board adaptor. Modular systems running on ±12V often lack a dedicated +5V rail, which some digital modules (like certain sequencers or clock dividers) require. The 301 can provide up to 500mA on +5V—enough to power several low-draw modules—via a jumper on the back. Flip it, and suddenly your pedal interface is also a power hub. Of course, that means you need to be careful: if your case already has +5V, enabling this feature risks a short. Documentation warns you, but it’s the kind of “gotcha” that’s bitten more than one eager builder.

Specifications

Key Features

Expression with Surgical Precision

Most pedal interfaces in Eurorack treat expression as a blunt instrument—turn a knob, get a voltage, hope it lands where you want. The 301 refuses that compromise. The Range knob lets you dial in exactly how much voltage swing your pedal produces, from a subtle ±1V wiggle to a full ±10V sweep. Pair that with the Offset control, and you can shift that entire range up or down by ±5V. Want your pedal to control resonance from 2V to 4V instead of 0V to 10V? Done. Need it to modulate pitch from -2V to +2V for a vibrato that doesn’t jump octaves? Easy. This level of control means you’re not just assigning a pedal—you’re sculpting its behavior to match your playing style. The dual LEDs (one red, one green) show real-time polarity: green brightens as the CV goes positive, red as it inverts. It’s not a meter, but it’s enough to tell if your pedal is tracking correctly or if the pot’s drifted.

Sustain That Feels Like a Piano

The sustain input isn’t just a gate trigger—it’s designed to mimic the feel of a piano damper pedal. Plug in a standard momentary footswitch (like a Boss FS-5U), and the output sends a clean +5V gate when pressed. The LED pulses with each stomp, giving visual confirmation even in dark setups. While it doesn’t support half-pedaling like high-end MIDI controllers, the response is snappy and reliable, perfect for holding down drones, freezing delays, or latching sequencers. In a live set, this single button can be the anchor—letting you freeze a texture while you repatch or reach for another pedal. It’s the kind of simple, tactile control that reminds you modular doesn’t have to be complicated to be expressive.

The Hidden Power Node

Flip the module over, and you’ll find a tiny jumper that unlocks a feature no other pedal interface offered at the time: +5V output to the bus board. Most Eurorack cases provide only ±12V, but some modules—especially those with digital logic or microcontrollers—require +5V to run. Instead of adding a separate power distributor or modifying your PSU, the 301 can source up to 500mA on +5V, enough to power several low-draw modules like clock utilities or logic gates. The jumper must be manually installed on the back of the PCB, and documentation warns against enabling it if your case already has +5V, as it could cause a short. But for DIY builders or compact cases lacking that rail, it’s a godsend. Just don’t forget it’s there—accidentally daisy-chaining to another +5V source could fry something.

Historical Context

When the ADDAC 301 launched in 2013, Eurorack was still shedding its image as a boutique curiosity. Modular wasn’t yet the mainstream force it is today—most players were tinkerers, academics, or experimental musicians patching in basements. But live performance was becoming a bigger focus, and the limitations of hands-only control were obvious. Expression pedals and footswitches were standard on keyboards and guitar effects, but modular lagged behind. Companies like Intellijel and Doepfer offered basic gate interfaces, but few gave performers real control over CV mapping.

ADDAC, a Portuguese boutique known for clean design and utility modules, saw the gap. The 301 was part of their 300 Series—dedicated interface tools rather than sound generators. It arrived just as performers like Kim Bost and Hainbach were demonstrating that modular could be dynamic and physical, not just cerebral. Suddenly, having a pedal to control filter sweeps, delay feedback, or sample position wasn’t a gimmick—it was essential. The 301 wasn’t flashy, but it was reliable, precise, and—critically—affordable. At $90, it was half the price of some competing solutions, making it accessible to players building their first case.

It also arrived before the Eurorack gold rush of the mid-2010s, when prices inflated and modules became collectible. The 301 stayed in production until around 2020, when ADDAC shifted focus to more complex systems. It never got a “Mark II,” but its design was so solid it didn’t need one. Today, it’s remembered not as a sonic powerhouse, but as a quiet enabler—one of those modules that made modular feel like an instrument, not just a lab experiment.

Collectibility & Value

The ADDAC 301 Floor Control isn’t a collector’s grail, but it’s far from irrelevant. On the used market, it typically sells for $80–$120, depending on condition and whether it includes the original box and jumper. Units described as “mint, never used” occasionally fetch $130, but that’s rare. Unlike rare oscillators or vintage filters, the 301 isn’t hoarded—it’s used, passed on, or sold when a player upgrades. That keeps supply steady and prices reasonable.

Condition-wise, it’s a robust module. There are no moving parts on the PCB, and the jacks are standard Neutrik types that can be replaced if worn. The main failure points are user errors: enabling the +5V jumper in a case that already has +5V (which can damage the PSU or other modules), or using a damaged expression pedal cable that shorts the stereo jack. The trim pots for Range and Offset can drift over time, especially if over-tightened, but recalibration is straightforward with a multimeter.

When buying used, check that the LEDs respond correctly—no flickering or dimness—and that the CV output tracks smoothly across the pedal’s range. Test both the positive and inverted CV outputs with a voltmeter or connected module. Also, inspect the back for the +5V jumper: if it’s installed, confirm with the seller whether their case used it, and make sure your own setup can handle it. A unit with the jumper removed is actually safer for most modern cases.

Restoration is minimal—no recap needed, no firmware updates, no alignment. If the front panel is scratched, replacements are available from third-party vendors, but the original black anodized aluminum holds up well. Given its utility, the 301 is more likely to be retired due to obsolescence (if a player moves to a pedal interface with MIDI or multiple zones) than failure. But for anyone still running a classic Eurorack case, especially one lacking +5V, it remains a smart, functional addition.

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