4ms Dual Looping Delay (2010–Present)

Name: 4ms Dual Looping Delay
Brand: 4ms

A digital delay that doesn't pretend to be analog. It has crystalline repeats, deep clock sync, and two full loops in 20HP.

Overview

Patch in a simple melody, set the clock, and the rig starts echoing back sound and time, layered and in step. That's the 4ms Dual Looping Delay. It doesn't chase warmth or tape wobble. It goes for precision, flexibility, and rhythmic depth, and it's built for sounds that unfold over minutes, not milliseconds. Two fully independent delay/loop channels lock to a shared clock, and feedback becomes something you compose with.

The DLD dates to the early 2010s, when Eurorack was shifting from analog purism to digital experimentation. It holds 88 seconds per channel, nearly three minutes of total loop memory. That kind of headroom was unheard of in compact modular formats at the time, and even now few modules match it. Each channel runs at 48kHz with 16-bit resolution (with an optional 24-bit upgrade path). The delay is clean and transparent and doesn't color the source, unless you want it to via feedback routing, external processing, or creative CV manipulation.

The two channels aren't just stacked delays. Each one sets its own timing through divisions and multiplications of a master clock. You can run one at 1/4 note and the other at 5/8, or stretch one into a glacial 32-beat loop while the other stutters in 1/16 triplets. The clock has dedicated inputs and outputs, so it locks to sequencers, drum modules, or external gear. It can follow time, and it can also define it.

There are no menus, no LCD screens, and no endless button presses. The front panel has knobs for time, feedback, mix, and delay level, with CV control over every parameter. It's sparse, with color-coded sections separating inputs (black) from outputs (white), and illuminated buttons for Infinite Hold, Reverse, and Ping (tap tempo). Those buttons click and glow, which makes looping feel physical.

Specifications

Manufacturer	4ms Company
Production Years	2010–Present
Original Price	$495 (assembled)
Module Width	20 HP
Depth	50 mm
Power Requirements	+12V @ 120mA, -12V @ 30mA
Sampling Rate	48 kHz
Bit Depth	16-bit (24-bit upgrade available)
Maximum Delay Time	88 seconds per channel
Total Loop Time	Up to 2 minutes 56 seconds
Frequency Response	0 Hz (DC) to 24 kHz (-1.7 dB)
Signal-to-Noise Ratio	Extremely quiet, low-noise design
Inputs	Audio In A/B, Time CV A/B, Feedback CV A/B, Mix CV A/B, Delay Feed CV A/B, Clock In, Hold In, Reverse In
Outputs	Audio Out A/B, Send A/B, Return A/B, Clock Out, Loop Clock Out A/B
Normalization	Inputs and outputs normaled for mono operation
CV Control	All major parameters CV-controllable
Tap Tempo	Yes (Ping button)
Reverse Playback	Yes, per channel
Infinite Hold	Yes, per channel
Weight	0.5 lbs (227 g)

Key Features

Two Delays, One Clock—Rhythmic Symbiosis

Both channels sync to a single clock, but each interprets time differently. The Time knob doesn't set milliseconds. It sets rhythmic divisions and multiples. Turn it to "4" with the toggle in center position and you get a 4-beat loop. Flip the toggle to "+16" and it becomes 20 beats. Set it to "1/8" and the base clock is divided by eight, which gives you polyrhythms with a flick of a switch. You can build entire pieces around two loops drifting in and out of phase, feeding each other over minutes. The clock I/O can sync delays to sequencers, and the Loop Clock Out can drive other time-based effects.

Send/Return: The Hidden Playground

Between the two channels sit Send and Return jacks, one per side. Patch a filter, a second delay, or a granular processor into the Send/Return loop and the delay starts transforming the signal instead of just echoing it. Feedback can be routed through external effects, so you can build resonant feedback chains that spiral into self-oscillation or ambient washes. The manual warns that you might hear something you played minutes ago resurfacing unexpectedly. With nearly three minutes of total memory, that's what it does. It's a feature, not a bug.

CV-Driven Time Manipulation

Every major parameter accepts CV: time, feedback, mix, and delay level. Patch a slow LFO into the Time CV and the delay length swells and contracts. A random stepped generator on feedback creates unpredictable decay patterns. An envelope follower from a drum hit can momentarily boost the mix, so delays punch through only on transients. There are no onboard attenuators, so you'll want to pair it with attenuators or use buffered mults. The Time knob responds to both absolute CV and offset, so you can hold a base delay time while an LFO adds rhythmic wobble.

Historical Context

The Dual Looping Delay arrived in 2010, when Eurorack was still dominated by analog oscillators, filters, and envelopes. Digital modules were often viewed with suspicion and seen as clunky, opaque, or too "computer-like." 4ms had already carved a niche with the Spectral Delay and the Ensemble Oscillator, but the DLD was accessible, immediate, and musical without relying on analog warmth. It drew inspiration from early digital delays like the Lexicon PCM42 and the EMT 250, machines prized for their clarity and precision, not their coloration.

The DLD wasn't a retro reissue. It was aimed at a new kind of modular musician, one who thought in terms of systems, feedback loops, and generative composition. Most delay modules at the time offered a few seconds of echo at best, so the DLD's 88-second capacity was revolutionary. It fit a broader shift in modular culture from short-form sound design to long-form, evolving textures. Artists like Tim Exile and Richard Devine, who used looping and feedback as core compositional tools, found a natural home in it.

Competitors like the Qu-Bit Nebulae or the Make Noise Mimeophon offered more texture and manipulation, but they came later, with higher complexity and cost. The DLD stayed the no-nonsense, high-capacity workhorse. It's less about mangling sound and more about sustaining and layering it over time.

Collectibility & Value

The 4ms Dual Looping Delay has never been "rare" in the traditional sense. It's been in continuous production since 2010, with consistent availability through major retailers. That doesn't make it common on the used market, though. Well-maintained units in good condition typically sell between $450 and $550, and black-panel versions (the standard) are the most prevalent. The 24-bit upgrade, if factory-installed or properly retrofitted, can add $50 to $75 to resale value, though it's not a dramatic premium.

What makes the DLD a keeper isn’t scarcity, but reliability and utility. Unlike some early digital modules that suffered from firmware bugs or power sensitivity, the DLD has a solid track record. Failures are rare, but when they happen, they’re usually tied to power issues—specifically, reverse polarity or overvoltage. The module lacks onboard protection, so a misplugged power cable can fry the board. Technicians report that the most common repair is replacing the microcontroller or RAM chips, which are surface-mount and require skilled rework. There’s no user-serviceable parts inside; if it fails, it’s a send-back-to-4ms situation.

Firmware matters too. The DLD has received several updates over the years, including the v5 Send-Return Pre-Loop firmware, which adds advanced routing options. Units with older PCBs (v1.2-F446) can't run this firmware, so buyers should check revision history. A module with outdated firmware isn't broken, but it's missing features that many users now consider essential.

For collectors, the DLD isn’t about hunting down vintage variants or limited editions. It’s about owning a module that does one thing exceptionally well: long, clean, synchronized looping. It’s the kind of module that, once you’ve used it, you don’t want to patch without. It’s not flashy, but it’s foundational. And because it’s still in production, there’s no urgency to buy—just the quiet confidence that if you need two minutes of pristine delay, this is still one of the best ways to get it.