4ms Row Power 25 (2022–)

It doesn’t make sound, but if your modular doesn’t run without it, it’s the most important module you’ll never hear.

Overview

The Row Power 25 (RP25) from 4ms Company isn’t flashy. No knobs, no blinking lights beyond a single power indicator, no patch points—just clean, quiet, reliable juice for your Eurorack system. But for anyone building a compact or portable case, this 4 HP power supply is a quiet hero. Introduced in June 2022, it’s part of 4ms’s modular power ecosystem designed for flexibility, efficiency, and real-world usability. It doesn’t generate tones, but it absolutely shapes your experience—because when your modules hum, drop notes, or behave erratically, you’re not dealing with a synth problem. You’re dealing with a power problem.

And that’s where the RP25 steps in. With 25W of total power output, it’s built to run a small-to-mid-sized row of modules without breaking a sweat. It’s not the biggest in the Row Power family—there’s the Row Power 35 and the newer Row Power 45 above it, with the Row Power 40 now discontinued—but it hits a sweet spot: small enough to fit in skiff cases, powerful enough to feed a functional row of gear, and smart enough to play well with others. It’s not just a power supply; it’s a building block.

What sets it apart isn’t raw output, but thoughtful engineering. It’s skiff-friendly at just 25.6mm deep—even with the power connector attached—so it won’t blow out the back of a tight case. It runs cool, thanks to efficient regulation, and keeps noise off the rails so your oscillators stay clean and your filters don’t buzz. And because it’s independently regulated on each voltage rail (+12V, -12V, +5V), cross-talk between modules is minimized. That means your digital sequencer won’t inject glitches into your analog VCOs just because they’re on the same row.

It’s also built to scale. Need more power? Daisy-chain multiple Row Power units together using the dual power jacks. One wall-wart can feed three to five RP25s, making it a cost-effective and tidy solution for larger systems. And thanks to hot-swappable design, you can plug or unplug rows without powering down the whole rig—a rare and appreciated convenience in the modular world.

Specifications

Key Features

Daisy-Chaining Without the Drama

One of the RP25’s standout features is its ability to daisy-chain with other Row Power modules and 4ms Pods—portable cases that double as power hosts. Two dedicated power jacks make this possible, allowing you to link multiple units in sequence. But what’s really clever is the on/off switch: it cuts power to the local row without breaking the chain. That means you can power down one section of your system—say, a noisy digital row during a quiet patch—while keeping the rest of your case alive. No need to reboot, no glitching, no re-patching. It’s a small detail that speaks volumes about how 4ms thinks about real-world use.

Built for Builders, Not Just Buyers

The RP25 isn’t just a drop-in module. It’s a platform. Those “easily soldered holes” on the back? They’re for custom power distribution—perfect if you’re wiring your own bus board or using MTA156 connectors. And the 16-pin slot supports Flying Bus Boards or standard Bus Boards, giving you multiple ways to connect. This isn’t a one-size-fits-all solution; it’s a toolkit. Whether you’re building a flight case, a desktop skiff, or a wall-mounted monster, the RP25 adapts instead of demanding.

Cool, Clean, and Quiet

It’s not just about delivering power—it’s about delivering clean power. Each voltage rail is independently regulated with high-grade components, which means less noise, less ripple, and fewer surprises. Owners report low noise performance, which is critical when running sensitive analog circuits or high-gain digital modules. And because it’s efficient, it runs cool—no need for fans or heatsinks that eat up space or add noise. In a world where some power supplies turn into space heaters, the RP25 stays chill.

Hot-Swappable by Design

Most Eurorack systems require a full power cycle to safely connect or disconnect modules. Not so with the Row Power ecosystem. The RP25 supports hot-swapping of entire rows, meaning you can plug in or remove a powered section without shutting everything down. This is a godsend for live performers, sound designers testing new modules, or anyone who hates rebooting their entire setup just to add a new filter. It’s a feature that feels futuristic but works flawlessly in practice.

Collectibility & Value

The Row Power 25 launched at $99.00, and that price still holds at multiple retailers like Control Voltage and Big City Music, though availability fluctuates. Some listings, like one on Reverb, show a higher price of $124.80 plus $34.36 shipping for a brand-new unit, suggesting demand can push prices above MSRP when stock is tight. In the UK, it’s available for £95.00 including VAT. There’s no data on common failures or long-term reliability issues—no surprise, given its simple, regulated design and lack of moving parts. Maintenance is effectively nonexistent; there’s little to wear out beyond the power connector or solder joints if used in a custom build. As of now, it’s not a “collector’s item” in the vintage sense—production began in 2022, and it’s still actively sold—but for modular builders, it’s a staple. Its value lies in utility, not rarity.

eBay Listings

4MS ROW POWER 25 MODULE : NEW : [DETROIT MODULAR]

$99.00

4MS Row Power 25 Power Supply Modular EURORACK - NEW - PERFE

$99.00

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