4ms Dual Looping Granular Sampler (2023–)

A stereo sampler that reads samples off a microSD card and lets you tear them apart with voltage

Overview

It starts with a click. Not the polite tap of a keyboard, but the sharp, satisfying mechanical snap of the Sampler’s Play button — the kind that tells you something real just happened. Then comes the sound: a voice from Poland scolding someone about beetroot, a glitchy granular smear of a synth stab, a perfectly looped 808 kick with just enough grit to feel alive. This isn’t some sterile digital playback module. The 4ms Dual Looping Granular Sampler — though it’s just called the Sampler on the front panel — is a hands-on, no-compromise portal into sample manipulation that feels more like sculpting sound than triggering clips. It arrived in mid-2023 as a streamlined, more accessible sibling to the beloved Stereo Triggered Sampler (STS), but don’t mistake it for a budget version. It’s a focused evolution, packing nearly all the STS’s power into a tighter 12HP frame and a lower price, with firmware that quietly expanded its capabilities from day one.

Everything is right on the panel. There is a knob for sample selection, another for start position and a third for playback length. Each has a CV input, so an LFO can sweep through a sample, or a sequencer can jump between samples. Dial the length down past 50% and the module moves from traditional sampling into granular territory. At the shortest setting it plays back fragments as brief as 8ms, which gives stuttering textures, pitch-shifted clouds and rhythmic glitches. It is not a full granular synth like the Morphagene. It is granular-adjacent, and it is intuitive and immediate.

It records too, straight into 48kHz/24-bit WAV files on the included 16GB microSD card. Plug in a mic, a synth or your DAW's output, hold Play and Reverse, and it captures. Recordings are split into 4GB chunks so you don't hit filesystem limits. You can resample your own manipulations by patching one channel's output into the other's input, which builds layered loops in real time. There are limits. Unlike the DLD or Morphagene, you can't layer multiple recordings on top of each other like overdubbing. What you record is what you get, with no sound-on-sound. The firmware allows cue points if you enable them in the settings.txt file, but it is not as deep as a dedicated granular engine. The strength here is balance: deep enough for serious sound design, and never more than three knobs away from a new idea.

Specifications

Key Features

Two Channels, Infinite Possibilities

The "Dual" in the name is real. This is a two-channel stereo sampler. Each channel has independent controls for sample selection, start position, length, pitch and reverse, plus dedicated CV inputs for every parameter. You can play two completely different samples at once, pan them across the stereo field and modulate them separately. You can also patch them together. Route Channel A's output to Channel B's input and trigger a resample, and you capture your own effects chain in real time. Put a filter, a delay or a resonator in between and the sound mutates with every pass.

Granular Scrubbing Without the Complexity

There is no "grain size" knob. The Length knob does that job. At full rotation you get the entire file. Between 50% and 100%, you are playing back 200ms to 5 seconds of audio. Below 50% the behavior changes and the module shifts into granular playback mode, slicing the sample into tiny fragments. The sample stutters, smears and pitch-shifts in ways closer to granular synthesis than to traditional looping. Owners report that the transition point around 12 o'clock on the knob can feel abrupt, almost like an envelope is kicking in, even with envelopes disabled. Pair it with CV control over start position and you can sweep through a vocal sample and pull out syllables, breaths and artifacts.

Firmware That Grows With You

The Sampler ships with usable firmware, but 4ms kept updating it. Updates are delivered as audio files. You play one into the Record input and the module rewrites its own firmware, so you don't need to remove the card or connect to a computer. One early addition was the ability to save your last-selected sample and bank, so the module powers up where you left off. Owners had been asking for it. Another is cue point support. If you embed markers in your WAV files (Reaper is recommended), the Start Position and Length knobs snap to them, which makes it easy to jump between verses, choruses or specific transients. It is not enabled by default. You have to edit the settings.txt file on the card.

Historical Context

The Sampler came out of 4ms's long run of looping, delay and sample manipulation in Eurorack. The company built its reputation on the Dual Looping Delay (DLD). The Stereo Triggered Sampler (STS) followed, with higher fidelity, more storage and a cleaner interface. But at 24HP and nearly $600, it was a commitment. The Sampler arrived in June 2023 as a response to demand for something more accessible in both price and panel space. It coincided with NAMM 2023 and Superbooth, where 4ms also introduced the Looping Delay, a more affordable take on the DLD. It was positioned as the entry point into 4ms's sample-based synthesis: not as deep as the STS, not as experimental as the Morphagene. It landed in a crowded market, competing with the Bastl Instruments Soft Bite, the Critter & Guitari Organelle and the Elektron boxes.

Collectibility & Value

As of 2026, the Sampler is still too new to be "vintage" in the traditional sense, but it is already sought after in the Eurorack community. The built version sells for around $300 new, while the DIY kit is $199. On the used market, expect to pay $220-$260 for a clean unit, depending on condition and whether it includes the original SD card and accessories. Units made before 2025 are 16HP and slightly deeper, but functionally identical. They are just harder to fit in smaller cases. Failures are rare, but the microSD card slot can wear out with frequent swapping, and the mechanical buttons may eventually need replacement after years of heavy use. The bigger risk is firmware. Check that the module has been updated to at least v1.0.1, as earlier versions lack critical fixes and features like bank recall. When buying used, ask if the seller has enabled cue point support and whether the card is included. A unit without the card, or with an outdated firmware file, is essentially a paperweight until you can load new samples. Maintenance is minimal. Keep the card clean, avoid hot-swapping during playback (wait for the Busy light to go off), and store it with the card ejected if it won't be used for long periods.

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