4ms Micro Modular Recorder (2019–)

A tiny stereo recorder that fits in a synth rack and sounds like a studio machine, if you can survive its cryptic menu system.

Overview

The 4ms Micro Modular Recorder lives in your rack, runs off your case power, and records with near-flawless fidelity, no computer required. It's only 6HP, so it fits into even the tightest systems. It's a full-featured stereo WAV recorder for documenting patches, layering live loops, or bringing in field recordings. It's not a sampler in the traditional sense. No pitch-shifting, no slicing, no envelopes. It's a recorder in the purest form: press a button, capture sound, play it back later, all in 24-bit/96kHz quality.

The design philosophy is an analog cassette deck from the '80s, tactile and immediate, but with modern digital reliability. You can record from line-level sources, headphone outs, or direct modular signals, and a gain knob boosts low-level inputs up to +20dB. The dual LED meters show your input levels, and the red/green push-button tells you whether you're armed, recording, or playing back. It's simple until you need something slightly more advanced, like picking a different file or changing the sample rate. The interface relies entirely on LED patterns and knob-twisting, with no screen or labels. To browse recordings, hold the play button and turn the gain knob while watching LEDs blink in binary. To switch from stereo to mono, you go into a system menu that needs a five-second button press and careful tapping. It works, but it isn't intuitive, and in a live set it can feel like decoding hieroglyphs.

The sound quality is exceptional. Recordings are lossless WAV files on a microSD card (Class 10 or better recommended), with selectable settings of 96kHz/24-bit, 48kHz/24-bit, or 44.1kHz/16-bit. Owners report that the audio is indistinguishable from direct computer recordings, which is a rare win in the modular world, where digital modules often cut corners on converters or power filtering. The inputs are normalized, so a mono signal plugged into the left input routes to both channels. A trigger input starts or stops recording or playback from external clocks or sequencers, and if you stack multiple units, you can mult the trigger to build a crude multitrack setup. It's not meant to replace a DAW. It's for sketching, capturing happy accidents, or looping ambient textures to mangle with filters, delays, or granular processors downstream.

Specifications

Key Features

Studio-Grade Recording in Eurorack Clothing

Many digital Eurorack modules use cost-reduced ADCs or share power rails with noisy digital circuits. This unit doesn't. It delivers clean, transparent recording that holds up in professional contexts. The 24-bit/96kHz capability gives dynamic range and frequency response that match modern studio standards, and the low-noise design means no audible hiss even when boosting quiet sources. That makes it usable for vocals, acoustic instruments, or field recordings directly into your case, not just modular patches. The gain knob with up to 20dB of boost lets you plug in a guitar, a mic preamp output, or a line-level drum machine and record at good levels without external gear. The normalized inputs also simplify mono recording, so you don't need a splitter cable for a single source.

Triggered Operation for Seamless Integration

The trigger input is one of the most practical features. It starts and stops recording or playback from external CV/Gate signals. You can sync a recording to a specific sequence, trigger playback of a loop at a precise moment, or use a clock divider to create delayed overdubs. In playback mode, each incoming trigger restarts the most recent recording, so it behaves like a one-shot sample player. It doesn't support random access or CV-controlled file selection, which modules like the Make Noise Morphagene or the 4ms Stereo Triggered Sampler do offer. The simplicity keeps it reliable. There's no loading time and no buffering, just immediate playback. For live performance that immediacy is a strength, even if it lacks the sophistication of more advanced samplers. The trigger input also works in record mode, so you can begin recording on the downbeat of a sequence, which helps when documenting generative patches that evolve over time.

MicroSD Management and File Browsing

The microSD card is a mixed bag. Storage is cheap, expandable, and hot-swappable. You can pull the card (when the busy light is off) and plug it into a computer to back up or edit files. But file management happens entirely inside the module's opaque interface. To browse recordings, you hold the play button and turn the gain knob, with LEDs indicating which file is selected. With more than eight files, the system uses blinking patterns and color shifts that can be confusing under stage lights. There's no delete function on the module. If you record a bad take, it stays on the card until you pull the card and erase it on a computer. Some users work around this by labeling files sequentially and keeping a mental note of the keepers. Firmware updates have improved stability and added features over time, but the core interface remains minimal. 4ms evidently prioritized reliability and low part count over user-friendliness, which pays off in durability and frustrates in daily use.

Historical Context

The Modular Recorder arrived in 2019, when Eurorack was shifting from purely analog signal generation to hybrid systems with digital recording, sampling, and effects. Modules like the TipTop Audio One, Erica Pico Drums, and MTM Radio Music offered basic playback, but few focused on high-fidelity recording with flexible I/O. The Modular Recorder filled that gap. It wasn't trying to be a sampler or a looper, just a no-compromise recorder that lived in the rack. Its design echoes early digital portastudios and DAT machines, tools meant to capture ideas quickly without a computer. It also fits 4ms's reputation for utilitarian, no-frills modules that put function ahead of flash. Compared with the company's more experimental offerings like the Spectral Multiband Resonator or the Dual Looping Delay, it's deliberately straightforward, almost austere. It records well, runs reliably, and stays out of the way.

It also arrived alongside 4ms's Listen series of mixers, which share the same modular-level I/O approach. The Listen Four, for example, accepts both line and modular signals, which makes it a natural partner for the Modular Recorder. Patch your synth into the mixer, monitor through headphones, send a feed to the recorder, and capture your performance without leaving the case. That makes the module a building block for standalone modular rigs, for buskers, live performers, or anyone who wants to work without a laptop.

Collectibility & Value

The Modular Recorder isn't rare. It's still in production and widely available, and it has a loyal following among modular users who value high-quality audio capture. On the used market, prices typically range from $180 to $220 depending on condition, with mint units in original packaging closer to $250. It's a functional tool rather than a collector's item, so most units in circulation are well-used. The design has few failure points: no moving parts, minimal surface-mount components, and a simple power draw that won't stress most cases. The most common issue is microSD card corruption, usually caused by removing the card while the busy light is on. This can brick the module temporarily until a formatted card is inserted, but it rarely causes permanent damage. Some early firmware versions had bugs with file indexing, but updates have resolved them.

When buying used, check that the gain knob turns smoothly and that both input jacks are secure. Loose jacks are the most frequent mechanical failure. Test the trigger input with a clock source to confirm recording and playback can be controlled externally. Verify that the LED meters respond correctly to input signals and that the module recognizes a known-good microSD card. Because the interface is menu-driven, ask the seller whether they've used the browsing or settings functions successfully. A unit that only records and plays back the most recent file might be hiding a deeper firmware or card issue. For long-term ownership, keep a spare microSD card on hand and label it with a permanent marker to avoid mix-ups. The module needs no regular maintenance, but storing it in a dry environment will prevent corrosion on the contacts, especially if it's used in humid or live settings.

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