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 has no knobs, no blinking lights beyond a single power indicator, and no patch points. It just supplies clean, quiet power to a Eurorack system. This 4 HP supply suits compact or portable cases. Introduced in June 2022, it's part of 4ms's modular power ecosystem, which was designed for flexibility, efficiency, and real-world usability. It doesn't generate tones. But when modules hum, drop notes, or behave erratically, the problem is often the power, not the synth.

The RP25 puts out 25W total, enough to run a small-to-mid-sized row of modules. It isn't the biggest in the Row Power family. The Row Power 35 and the newer Row Power 45 sit above it, and the Row Power 40 is now discontinued. It's small enough to fit in skiff cases, powerful enough to feed a functional row of gear, and it plays well with other Row Power units.

The engineering is the selling point, not the raw output. 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 it keeps noise off the rails so oscillators stay clean and filters don't buzz. Each voltage rail (+12V, -12V, +5V) is independently regulated, so cross-talk between modules is minimized. A digital sequencer won't inject glitches into analog VCOs just because they share a row.

It also scales. For more power, daisy-chain multiple Row Power units using the dual power jacks. One wall-wart can feed three to five RP25s, which keeps larger systems cost-effective and tidy. The design is hot-swappable, so you can plug or unplug rows without powering down the whole rig. That's a rare convenience in modular.

Specifications

Manufacturer	4ms Company
Module Size	4 HP Eurorack format module
Module Height	3U
Physical depth	Skiff-friendly: only 25.6mm (1.01") with power connector installed.
Power Output	+12V @ 1.4A maximum, 1.0A recommended
Power Output	-12V @ 0.8A maximum, 0.5A recommended
Power Output	+5V @ 1.0A maximum, 0.8A recommended
Total power	The Row Power 25 provides 25W of power
Input	Powered by laptop-style DC power supply: 2.1mm barrel, positive center, 15V-20V.
Power consumption	1.4mA @+12V, 1mA @-12V, 0.8mA @+5V
Includes set of easily soldered holes for custom distribution systems	by soldering wires or MTA156 connectors
Provides a 16-pin slot	for Flying Bus Boards or Bus Boards

Key Features

Daisy-Chaining Without the Drama

The RP25 can daisy-chain with other Row Power modules and 4ms Pods, which are portable cases that double as power hosts. Two dedicated power jacks make this possible, so you can link multiple units in sequence. The on/off switch cuts power to the local row without breaking the chain. That lets you power down one section, say a noisy digital row during a quiet patch, while the rest of the case stays alive. No reboot, no glitching, no re-patching.

Built for Builders, Not Just Buyers

The RP25 is also a platform. The "easily soldered holes" on the back are for custom power distribution, useful if you're wiring your own bus board or using MTA156 connectors. The 16-pin slot supports Flying Bus Boards or standard Bus Boards, so there are multiple ways to connect. It fits a flight case, a desktop skiff, or a wall-mounted monster.

Cool, Clean, and Quiet

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 matters when running sensitive analog circuits or high-gain digital modules. It's efficient, so it runs cool, with no fans or heatsinks to eat up space or add noise.

Hot-Swappable by Design

Most Eurorack systems require a full power cycle to safely connect or disconnect modules. The Row Power ecosystem doesn't. The RP25 supports hot-swapping of entire rows, so you can plug in or remove a powered section without shutting everything down. That helps live performers, sound designers testing new modules, and anyone who hates rebooting the whole setup just to add a filter.

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, which suggests 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, which is no surprise given the 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. It isn't a "collector's item" in the vintage sense, since production began in 2022 and it's still actively sold. For modular builders, it's a staple.