4ms DLD (2015–)

Two channels of clock-synced looping delay that don't degrade and don't wobble. Digital memory, sample-accurate, with deep, evolving textures.

Overview

Patch in the 4ms DLD and set a long loop. Three minutes of silence, then a single plucked oscillator tone repeating with crystalline clarity. No wow, no flutter, no saturation smear. Just clean, sample-accurate repetition, locked to your system's tempo with the rigidity of a quartz oscillator. The DLD doesn't try to be vintage. It doesn't want to sound like a Binson or a Roland Space Echo. It's a modern, high-fidelity looping delay that treats time like architecture, not weathering tape.

The DLD is two independent 16-bit digital delays. Each one holds up to 2 minutes and 54 seconds of loop time at 48kHz in the default mode. That's nearly three minutes of audio memory per channel, which in Eurorack is borderline absurd. That kind of headroom wasn't common when the DLD launched around 2015, and even now few modules offer that depth without SD cards or external storage. It's not a looper in the traditional sense, because there's no record/start/stop button sequence. It loops by default, constantly recording into a buffer. You don't capture a phrase; you *define* it by setting the loop length with tempo-synced divisions, then freeze it with Infinite Hold. Once locked, the loop plays back perfectly. You can shift its start and end points in real time with the Feedback knob while holding Infinite Hold. This is called "Windowing," and it lets you scrub through older material buried deep in the buffer, including sounds you didn't know you'd recorded.

The DLD sits between delay and granular playback, especially when you modulate the Time parameter with CV. The delay time is quantized to musical divisions (1/8ths, whole beats, up to 32 bars), so you can dial in polyrhythms with precision. For a second loop running in quintuplets against your main sequence, set the Time switch to "=" and turn the knob to 5. For a micro-delay texture at 1/16th note, flip the switch down to "1/8" and adjust. Or bypass the quantization by holding the Infinite Hold button and twisting the Time knob. That puts you in free-run mode, where the delay time is continuous, good for sweeping effects or ambient smear.

Specifications

Manufacturer	4ms
Production Years	2015–
Original Price	$415
Module Size	20HP Eurorack
Depth	0.98" (25mm) maximum with power cable
Power Consumption	+12V: 188mA max, -12V: 48mA max, +5V: not used
Sampling Rate	48kHz
Bit Depth	16-bit default, 24-bit selectable via jumper
Maximum Loop Time	174 seconds (2:54) per channel at 16-bit, 88 seconds at 24-bit
Audio Input Range	0Hz (DC) to 24kHz, 16.8V peak-to-peak max before clipping
Audio Output Range	0Hz (DC) to 24kHz, +10.5V to -10.5V max, soft limiting
Input Coupling	AC or DC selectable via jumper
Feedback Range	0% to 110%
Delay Level Control	Independent of mix
Clock Input	Accepts external clock, trigger, or audio-rate signal
Clock Output	Main Ping, Loop A, Loop B (0V to 8.2V, low jitter)
CV Inputs	Time, Feedback, Level, Delay Feed, Reverse, Infinite Hold
Send/Return	Per channel, for external processing in feedback path
Firmware Updates	Via audio file playback into input
Included Accessories	16-to-16 pin power cable, 4 M3 knurled screws

Key Features

Time as a Musical Grid

The DLD doesn't measure delay time in milliseconds. It measures it in beats. The Time knob isn't a continuous dial. It's a 17-position switch that sets divisions relative to the master clock (Ping). With the Time switch in the center ("="), the knob sets the loop length directly: 1 beat, 2 beats, up to 16. Flip it up to "+16" and it adds 16 beats, so turning the knob to 4 gives you a 20-beat loop. Flip it down to "1/8" and it divides the value by 8, so you can dial in micro-rhythms like ⅛ or ¾ of a beat. This makes it easy to build polyrhythmic delays that lock into your sequencer. It isn't rigid, though. Hold the Infinite Hold button and twist the Time knob, and you're in unquantized mode, where the delay time is smooth and continuous.

Windowing: Digging Through Sonic Archaeology

Most loopers erase the past. The DLD keeps it. Even when you're not in Infinite Hold, the module is constantly recording into a circular buffer. When you engage Infinite Hold, it locks the current loop in place, but the rest of the buffer is still there, stretching back up to three minutes. Hold Infinite Hold and turn the Feedback knob, and you "window" into that buffer, shifting the loop's start and end points. That means you can pull in audio you played *before* you started looping, like a bass sequence from two minutes ago or a filtered noise sweep you thought was gone.

Send/Return as a Creative Playground

Each channel has its own Send and Return jacks, so you can patch external effects into the feedback path. Run the feedback through a filter and each repeat gets darker or brighter. Patch in a wavefolder and the repeats fold in on themselves, generating complex harmonics. Use a second delay and you've got a feedback matrix that can spiral into self-oscillation or ambient drones. The Delay Level knob controls how much signal enters the loop, independent of the dry/wet mix. So you can keep the output clean while feeding a distorted or compressed version back into the memory.

Historical Context

When the DLD arrived in the mid-2010s, Eurorack was full of boutique delay modules, many of them emulating analog or tape-based textures, complete with pitch wobble, saturation, and noise. The DLD did the opposite and embraced its digital nature. Inspired by high-end studio delays like the Lexicon PCM42 and the Eventide H3000, it offered pristine, sample-accurate repeats with none of the coloration. At a time when "character" was king, the DLD said, "What if clarity is the character?"

It also arrived alongside a wave of modules that treated time as something to manipulate: MakeNoise's Phonogene, Mutable Instruments' Clouds (later Plaits), and eventually the Qu-Bit Nebulae. Those modules leaned into granular or spectral processing. The DLD stayed focused on rhythmic precision and long-form looping. It wasn't trying to mangle sound; it was trying to preserve it, then let you sculpt it over time. Paired with the 4ms QCD (Quad Clock Distributor), it became a centerpiece of tempo-synced modular rigs, letting entire systems lock into a single timebase with sample-level accuracy. Firmware updates, delivered via audio file, added 24-bit recording, Ping Lock (which lets each channel lock to a different Ping time), and de-jittering algorithms for smoother external clock tracking.

Collectibility & Value

The DLD has never been cheap at $415 new, and it hasn't depreciated. On the used market, expect to pay $300 - $375 depending on condition, with units in excellent shape often selling for close to retail. It's not a rare module, but it's not common either, and demand remains steady among advanced modular users. There are no major failure points, but firmware updates can be finicky. Some users report issues booting into bootloader mode with older or underpowered Eurorack PSUs. The process requires holding Ping and both Reverse buttons while powering on, and if the power supply has a slow ramp-up or noise on startup, it might not trigger. A sturdy, modern PSU solves most of these issues.

The biggest thing to check when buying used is the firmware version. Units shipped with v3, but v5 added 24-bit recording, Ping Lock, and de-jittering. Updating is possible, but it requires playing a .wav file into the input, so make sure the audio input and output jacks work. Also verify the jumper for 24-bit mode is set correctly if you want that feature. Cosmetic wear is common. Knobs can get scratched, and the faceplate (available in white or black) can show scuffs, but the module is built like a tank. There are no serviceable parts inside for the average user. The PCB is dense SMD, and repairs should be left to professionals.

It’s not a beginner module. The interface is minimal, and the manual is essential. But for those who dive in, it becomes indispensable. It’s the kind of module you don’t realize you need until you hear it—then you can’t imagine a system without it.