4ms Buffered Mult (2013–Present)

A tiny traffic cop for your modular, glowing red and white as it quietly saves your patch from signal collapse

Overview

You don’t notice it until something goes wrong—until your VCOs drift flat because you daisy-chained a pitch CV through three oscillators, or your sequencer stuttered when you plugged in a second clocked delay. Then you slap in a 4ms Buffered Mult, and just like that, the system breathes again. It doesn’t make noise. It doesn’t shape sound. But it keeps everything from falling apart, and that makes it one of the most quietly essential modules in Eurorack. At just 3HP, it’s barely there—two buffered multiples, each splitting one input to three outputs, with the bottom channel normaled to the top so you can run a single source to six destinations. It’s not glamorous, but if your modular were a city, this would be the traffic light nobody sees until it burns out and the whole intersection descends into chaos.

The magic isn’t in what it adds, but what it prevents. Passive multiples are simple—just wires soldered together—but they don’t isolate the source. Plug one output-hungry module into a passive mult, and the voltage sags across all connected outputs. That’s fine for gates or triggers, but disastrous for pitch CV, where even a few millivolts of droop can throw tuning out of whack. The Buffered Mult uses opamps to actively regenerate the signal, so each output delivers a clean, full-strength copy. It handles audio, CV, gates, clocks, and even video-rate signals—thanks to wide-bandwidth opamps that don’t roll off in the upper harmonics. And because it’s built by 4ms, a company that cut its teeth on video synthesis, it plays nice with LZX and other modular video systems, making it a favorite in hybrid audiovisual setups.

But here’s the catch: it’s not a precision multiple. The manufacturer is upfront about it—this isn’t the module to use if you’re splitting 1V/oct pitch CV across multiple oscillators and expect perfect tuning. The resistors aren’t laser-trimmed, and there’s no calibration for exact gain or offset. In practice, most users won’t hear the difference on a single patch, but purists splitting finely-tuned scales across multiple oscillators might notice slight tuning discrepancies. That’s not a flaw—it’s a trade-off. The Buff Mult wasn’t built to be a metrology tool. It was built to be robust, affordable, and universally useful. It’s the difference between a lab-grade voltmeter and a multimeter you keep in your gig bag: one’s for calibration, the other’s for keeping things running.

Specifications

Manufacturer	4ms Company
Production Years	2013–Present
Original Price	$79
Module Size	3 HP
Depth	0.75 inches (18 mm)
Power Consumption (+12V)	13 mA
Power Consumption (-12V)	13 mA
Power Consumption (+5V)	0 mA (not used)
Power Connector	10-pin Eurorack power header
Inputs	2 independent inputs (top and bottom channels)
Outputs	6 total: 3 per channel, bottom normaled to top for 1-to-6 operation
Signal Type	Audio, CV, Gate, Clock, Video
Buffer Type	Opamp-based, wide bandwidth (video-rate capable)
Indicators	Bi-color LED per channel (white for positive, red for negative voltage)
Normalization	Bottom channel output normaled to top channel input
Included Accessories	10-to-16 pin power cable, M3 knurlie screws
Special Notes	Not a precision multiple; not recommended for exact 1V/oct CV splitting

Key Features

Video-Rate Bandwidth for Future-Proof Signal Integrity

Most buffered multiples are designed with audio and CV in mind, but the 4ms Buff Mult goes further—its opamps are specified for video-rate performance, meaning they can handle signals well into the MHz range without phase shift or amplitude loss. This isn’t overkill. It means that even fast audio transients, FM sidebands, or complex wavefolding retain their edge. More importantly, it makes the module fully compatible with modular video systems like LZX, where timing and amplitude precision are critical. In a patch that combines audio synthesis with video feedback or color modulation, the Buff Mult doesn’t just pass the signal—it preserves its integrity. That kind of foresight is why this module shows up in experimental AV rigs as often as it does in traditional Eurorack cases.

Bi-Color LEDs: A Diagnostic Tool in Plain Sight

Those little LEDs aren’t just for show. They’re real-time voltage monitors—white when the signal is positive, red when negative, brightness indicating amplitude. At a glance, you can tell if a CV is swinging bipolar, if a gate is stuck high, or if a clock signal is actually making it through. In a live patch, that’s invaluable. You can troubleshoot a dead envelope without a scope, or confirm that your LFO is actually outputting before you patch it to six destinations. It turns a passive utility into an active diagnostic hub. And because the LEDs respond to both audio and control voltages, they add a subtle visual rhythm to your case—flickering in time with your sequence, pulsing with your beats, making the invisible visible.

Normalization That Scales With Your Needs

The way the two channels are normaled—bottom output to top input—means you can use it as two independent 1-to-3 multiples, or plug into the top input and get a single 1-to-6 distribution point. That flexibility is rare in such a small footprint. Most 3HP multiples force you to choose: split one thing six ways, or two things three ways. The Buff Mult gives you both, dynamically. Need to send a clock to six sequencers? One cable. Want to split an LFO to three destinations and a modulation source to another three? Use both channels separately. It’s not just convenient—it’s adaptive. In a crowded case where every HP counts, that kind of dual-role design is a quiet triumph of engineering.

Historical Context

When the 4ms Buffered Mult launched in 2013, Eurorack was growing fast, but utility modules were still an afterthought for many builders. Passive multiples were everywhere—cheap, simple, and space-efficient—but their limitations were becoming obvious as patches grew more complex. Modules were pulling down CV, clocks were misfiring, and live performers were getting glitched signals mid-set. The need for active buffering was real, but most buffered multiples were either oversized, overpriced, or built with audio-only bandwidth in mind.

4ms stepped in with a design that reflected its roots in experimental audiovisual synthesis. The company had already made waves with the Spectral Multiband Resonator and the Dual Looping Delay, but the Buff Mult was different—deliberately unglamorous, built for function over flash. It wasn’t the first buffered multiple, but it was the first to combine video-rate performance, visual feedback, and intelligent normalization in a 3HP package at under $80. That combination hit a sweet spot: accessible enough for beginners, robust enough for touring artists, and flexible enough for video artists. It arrived just as modular was shifting from niche curiosity to mainstream tool, and it became a staple—not because it made new sounds, but because it made everything else work better.

Competitors like Intellijel’s Buffered Multiple and Mutable Instruments’ Yarns offered precision or MIDI integration, but they were either larger or more expensive. The Buff Mult didn’t try to do everything—it did one thing, and did it well. It wasn’t a Swiss Army knife. It was a single, perfectly sharpened screwdriver.

Collectibility & Value

The 4ms Buffered Mult has never been rare—production has been steady since 2013, and it’s widely available from dealers and the 4ms website. That means it doesn’t trade at a premium, and used units typically sell for $50–$65, depending on condition. New old stock or mint-condition modules with original packaging might fetch $70, but there’s no collector’s markup. This is a tool, not a trophy.

Failures are uncommon. The circuit is simple, with no moving parts or delicate components. The most frequent issue reported is LED burnout from static discharge during patching, but even that’s rare. The opamps are robust, and the power draw is low enough that it won’t stress even marginal power supplies. The only real caution is the one 4ms emphasizes: don’t use it for precision pitch CV. Owners who expect lab-grade accuracy will be disappointed. But for everything else—clock distribution, audio splitting, modulation routing, video signal buffering—it’s nearly bulletproof.

When buying used, check that both LEDs respond to signal and that all six outputs pass sound. A quick test with a sine wave and multimeter will confirm no voltage drop across outputs. Also verify the normalization—patch a signal into the top input and confirm it appears on all six outputs. If it doesn’t, the normalization jumper may be damaged, though this is extremely uncommon.

Maintenance is minimal. No calibration, no firmware, no user-serviceable parts. If it powers up and the LEDs light, it’s almost certainly working. That reliability is part of its appeal. In a world of complex, temperamental modules, the Buff Mult just works.