4ms Dual EnvVCA (2020–)

Two channels of analog envelopes and VCAs that cover everything from glacial drones to audio-rate chaos, and make no claim to be more than they are.

Overview

The Dual EnvVCA has no flashing lights and no menus. It has no wavefolding, no shape morphing and no digital trickery. What you get is two analog envelope generators paired with clean exponential VCAs. Each channel is fully independent. You use them to put dynamics into your sound or to make modulation sources. It's the module for when you're tired of scrolling through screens or untangling CV spaghetti just to make a simple gated swell. It's also more flexible than the panel suggests. It can act as an LFO, a slew limiter, or a crude oscillator when pushed into audio rate.

Each channel has sliders for rise and fall, plus a three-way range switch. Timing runs from fast attacks (down to ~125µs) out to 30-minute decays. That covers evolving ambient textures that shift over hours, and it covers snappy percussive envelopes for tight rhythmic work. The Time CV input extends the range further and lets you modulate the envelope speed in real time, so you can do tempo-synced swells or voltage-controlled decay sweeps. The sliders are linear, so adjustments are predictable and repeatable. No logarithmic guessing when you're after a subtle change.

The VCA is half of what makes this module useful. It's a low-noise, DC-coupled exponential amplifier, and it handles both audio and CV. Patch in a drone from your oscillator, shape it with the envelope, and send it out clean and click-free. Or send the envelope output to filter cutoff, pan, or another VCA elsewhere in your system. Since it works as both a dynamics processor and a modulation source, it saves space in a crowded rack. The VCA gain is internally linked to the envelope by default, unless you patch into the VCA CV input. You don't need extra cables for basic envelope shaping.

Specifications

Key Features

Envelope Flexibility Without the Fluff

The Dual EnvVCA has no waveshaping, no complex sequencing and no digital interpolation. It generates clean, reliable, voltage-controllable rise/fall envelopes. Each channel has independent rise and fall sliders with selectable short, medium and long time ranges. The Time CV input accepts a unipolar 0-5V signal and scales the envelope speed exponentially. You can sync it loosely to tempo or use another LFO for rhythmic variations. There are no separate CV inputs for rise and fall. Both share a single CV input, with attenuverters per parameter. That keeps the front panel clean and the workflow direct, and for many users the trade-off is fine.

Exponential VCAs That Stay Out of the Way

The VCAs are exponential, so they respond naturally to envelope control. That suits shaping the amplitude of audio signals with a classic synth swell. They're also DC-coupled, so slow modulation signals pass without low-end roll-off, which makes them useful for CV processing too. Input impedance is 100k and output impedance is 1k, so loading shouldn't be a problem when patched into other modules. The VCA gain is internally normalized to the corresponding envelope output, so basic envelope shaping works with no patching. To use the VCA independently, say to duck a drone with an external envelope, plug a CV into the VCA CV input. That breaks the internal link.

More Than Just Envelopes

With that wide timing range, the Dual EnvVCA works as an envelope generator and as a utility module. Set the rise and fall times to their shortest settings and patch the output into a VCO's pitch input, and you get a crude but functional audio-rate oscillator. Use the Follow input to make it a slew limiter or an ASR (attack-sustain-release) envelope. Engage the cycle button and each channel becomes a bipolar LFO with adjustable rise and fall slopes, which gives trapezoidal or triangle-like waveforms that evolve slowly. The end-of-rise and end-of-fall gate outputs let you trigger other events at set points in the envelope cycle.

Historical Context

The Dual EnvVCA arrived in 2020 as part of 4ms Company's push into modular utility and modulation tools. Many envelope generators at the time were leaning into digital control, shape morphing, and complex state sequencing (think MakeNoise Maths or ALM's PEG). The Dual EnvVCA stayed analog and simple. It didn't try to replace those modules. It offered a no-frills alternative for users who wanted predictable, hands-on control without CV overhead or menu diving.

It sits below the Shaped Dual EnvVCA, which adds waveshaping and independent shape CV. The Dual EnvVCA is the "workhorse" version, with two full envelope/VCA pairs in a compact 16HP footprint. It sold for $225, which was competitive with other dual-function modules given its full analog signal path and wide timing range.

Collectibility & Value

The Dual EnvVCA isn't a rare or sought-after grail. It's a production module that's still available directly from 4ms Company. Used units in excellent condition, with no cosmetic damage and fully functional sliders and jacks, typically sell for $175 - $200. Units with dirty or scratchy sliders may go for as low as $140, especially if they need servicing. The sliders are a known weak point because of the potentiometer quality. The module is 100% analog with no firmware or digital components, so it's relatively stable over time. But the sliders can accumulate dust or wear, leading to crackling in the CV or audio path. Contact cleaner often fixes this. Heavily worn sliders may need replacement.

The shared Time CV input is another thing to know about. It's convenient for modulating both envelopes at once, but it limits per-channel CV control unless you use a mixer or attenuator to split and offset the signal. Some users see this as a design flaw, others like the simplicity. The module draws 156mA on +12V and 131mA on -12V, so make sure your power supply can handle it, especially in larger systems. There are no known catastrophic failure modes - no overheating, no chip drift, no capacitor plague - so units in good physical condition are likely to perform as intended for years.

If you're building a modular system on a budget, or want a reliable envelope/VCA pair without the learning curve of more complex modules, the Dual EnvVCA remains a smart buy.

eBay Listings

4MS DEV Dual EnvVCA Dual Envelope VCA Eurorack Synth Module,

$225

4MS DUAL ENVVCA : NEW : [DETROIT MODULAR]

$225

4MS SHAPED DUAL ENVVCA : NEW : [DETROIT MODULAR]

$339

4MS Dual EnvVCA Dual Envelope + VCA Modular EURORACK - NEW -

$225

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