4ms Pingable Envelope Generator (2012–)

A dual envelope generator that doesn’t just follow your clock—it dances with it, morphs it, and throws it into rhythmic freefall.

Overview

You patch in a clock, hit the tap tempo button twice, and suddenly your envelopes are breathing in time with the rest of your rig—but not locked down, not rigid. The 4ms Pingable Envelope Generator (PEG) doesn’t just respond to pulses; it treats them like seeds, growing envelopes whose total duration is defined by the space between pings. That’s the core magic: the time between triggers sets the envelope length, not a knob. Want a snappy decay? Speed up the clock. Need a languid swell that stretches across bars? Slow the pings. It’s a paradigm shift from traditional AR or ADSR logic, where timing is internal and fixed. Here, timing is relational, social, almost conversational. The PEG listens, then answers in kind.

And it answers with precision. Each of the two channels runs independently, with full CV control over curve shape, skew, and ping division/multiplication—from 1/8x to 8x the incoming clock rate. That means one envelope can be a rapid-fire stutter synced to 16ths while the other creeps along at half-time, all from the same clock source. The curve knob morphs the rise and fall between exponential, logarithmic, linear, and interpolated responses, letting you go from punchy clicks to smooth swells without altering the total envelope time. Skew adjusts the balance between rise and fall, again without affecting overall duration—perfect for creating asymmetrical pulses that feel organic, not metronomic.

It’s not just an envelope generator; it’s a rhythmic brain. The PEG can cycle continuously (LFO mode), quantize to the next beat, trigger asynchronously, or respond to external gates with surgical accuracy. The End-of-Rise and End-of-Fall gate outputs give you precise timing signals for cascading modulation, while the Half-Rise option (switchable via jumper) opens up phase-shifting and quadrature possibilities. There’s even an analog OR output that takes the higher voltage of the two envelopes—ideal for creating complex, overlapping control voltages that evolve with every ping.

Specifications

Manufacturer	4ms Company
Production Years	2012–
Original Price	$345.00
Module Size	20 HP
Power Consumption (+12V)	60mA max (external 5V), 105mA max (internal 5V)
Power Consumption (-12V)	35mA max
Power Consumption (+5V)	40mA max (external 5V), 0mA (internal 5V)
Power Connector	16-pin Eurorack power header
Maximum Depth	1.0" (26mm) with power cable
Envelope Outputs	Main (scaled), +5V ENV (fixed 0–5V), OR (analog OR of both channels)
Gate Outputs	End-of-Rise (EOR), End-of-Fall (EOF), Half-Rise (jumper-selectable)
CV Inputs	Ping Div/Mult, Skew, Curve (per channel)
Control Inputs	T (toggle cycle), QNT (quantized trigger), Async (asynchronous trigger)
Controls	Ping Div/Mult knob, Curve knob, Skew knob, Scale knob, Bi-polar button, Cycle button, Tap tempo button (per channel)
Internal 5V Option	Jumper-selectable (internal generation from +12V or external supply)
Included Accessories	16-to-16 pin power cable, 4 M3 Knurlie screws
Firmware Versions	v4.2 (PCB v1.x), v4.3 (PCB v2.x)
Weight	Not specified
Dimensions	20 HP x 1.0" depth

Key Features

The Ping Concept: Envelopes That Sync, Not Just Trigger

Most envelope generators need a gate to start and a release time set by a knob. The PEG flips that script. The “ping” isn’t just a trigger—it’s the metronome that defines the entire envelope’s duration. Whether you’re tapping tempo manually or feeding it a clock from a sequencer, the time between pings becomes the total envelope cycle. That means your decay doesn’t just end when it feels like it; it ends in rhythmic lockstep with the rest of your patch. It’s the difference between a drummer playing a fill and one who’s actually listening to the bassline. This makes the PEG indispensable in generative patches, where timing coherence is everything. You can divide or multiply the ping clock from /8 to x8, letting one channel breathe in whole notes while another flutters at 32nd-note subdivisions—all from the same source.

Curve, Skew, and Shape Without Sacrificing Timing

The PEG’s real sorcery lies in how it maintains total envelope time regardless of curve or skew adjustments. Turn the curve knob and you’re not just changing the shape from logarithmic to exponential—you’re warping the envelope’s character while keeping it locked to the beat. A sharp attack can become a slow fade-in, but the entire envelope still finishes exactly when the next ping arrives. The same goes for skew: you can shift from a quick rise and long fall to a slow rise and snap decay, and the clock alignment holds. This is not just convenient—it’s transformative. It means you can modulate curve and skew with CV in real time, creating evolving textures that stay rhythmically coherent. Want a filter sweep that starts punchy and gradually melts into a smooth swell, all within the same bar? Patch CV into curve and let it evolve.

Modulation Depth and Utility Outputs

Beyond the main envelope outputs, the PEG is packed with utility. The Scale knob acts as an attenuating inverter, letting you flip the envelope polarity or scale it down for subtle modulation. The Bi-polar button centers the output around 0V, useful for modulating oscillators or VCAs symmetrically. The +5V ENV output is fixed at 0–5V, unaffected by scaling—perfect for driving modules that expect a standard CV range. The OR output is a quiet hero: it outputs the higher voltage of the two envelopes at any moment, creating complex, overlapping control signals that can drive filters, wavefolders, or even other envelopes. Patch both channels into a VCA and use the OR output to modulate its level—you’ll get a dynamic, interlocking rhythm that feels alive.

Historical Context

The PEG emerged in 2012, right as Eurorack was shifting from boutique curiosity to full-blown modular renaissance. At the time, envelope generators were mostly straightforward: ADSR, AR, maybe a loop mode. The Make Noise Maths had already redefined what a “function generator” could be, blurring lines between envelope, LFO, and wavefolder. The PEG didn’t try to out-math the Maths—it offered something different: rhythmic intelligence. While Maths excelled at abstract, voltage-controlled timing, the PEG embraced the grid. It was built for users who wanted their modulation to feel like part of the beat, not just layered on top. In an era where clock-synced LFOs and sequencers were becoming standard, the PEG was one of the first envelope generators to treat clock input as a first-class citizen. It didn’t just accept clock—it needed it to shine.

4ms, known for innovative designs like the Dual Looping Delay and Spectral Multiband Resonator, positioned the PEG as a “rhythmic modulation powerhouse.” It wasn’t the cheapest envelope option, nor the most analog-sounding—but it was the most rhythmically fluent. Paired with modules like the 4ms QCD (Quad Clock Distributor), it became the backbone of tightly synced, generative patches. Its firmware was actively developed, with updates improving stability and adding features—rare for hardware at the time. The fact that Softube later released an officially licensed plugin version speaks to its influence beyond the Eurorack world.

Collectibility & Value

The PEG has held its value remarkably well, with used units typically selling between $280 and $330 depending on condition and firmware version. New-old-stock or mint-condition units can still fetch close to the original $345 MSRP. Unlike some vintage gear that depreciates or becomes obsolete, the PEG remains in high demand because it does something few other modules can: it ties envelope timing directly to rhythmic context. There are no known fatal flaws in the design, but owners report that firmware updates (from v4.2 to v4.3) can resolve minor timing inconsistencies, especially in self-patched feedback loops. The manual includes clear instructions for checking and updating firmware, and 4ms provides the necessary files and guidance.

One quirk: the power jumper. The PEG can generate its own +5V internally or draw it from the power supply. Some skiff-friendly power systems don’t provide +5V, so users must set the jumper to internal generation—but this increases +12V draw from 60mA to 105mA per module. Always check your power supply’s +12V headroom if running multiple PEGs or other high-draw modules. The module itself is solidly built, with no reports of failing pots or jacks, and the PCB layout is clean and serviceable. Because it’s digital at its core (though the outputs are analog), it’s less prone to drift or noise than analog envelope generators—but it does require a stable clock source to perform at its best.

When buying used, verify the firmware version and ensure the tap tempo function works reliably. Some early units had inconsistent response if the firmware wasn’t updated. Also, check that the OR output behaves correctly—though failures here are extremely rare. For live use, the tap tempo buttons are tactile and responsive, but if you’re relying on external clock, make sure your source is stable. The PEG won’t fix a wobbly clock; it will faithfully reproduce it, quirks and all.