2hp Env (2010–2023)

Name: 2hp Env
Brand: 2hp

A two-stage envelope that fits in the gap where most modules just can’t reach—tiny, precise, and capable of everything from snappy transients to slow morphs.

Overview

Slap a patch cable into the 2hp Env and you immediately notice what’s missing: clutter. At just 2HP wide, it’s one of the narrowest envelope generators ever made for Eurorack, yet it doesn’t feel like a compromise. Turn the attack knob from fully counterclockwise to full clockwise and the response shifts from a near-instantaneous pop to a lazy, swelling rise that can stretch out over several seconds—perfect for ambient pads or filtering in slow motion. The decay does the same on the way down, and the real magic lies in how smoothly it transitions across that range. There’s no digital stepping, no jitter—just a clean, analog glide that feels surgical when you need precision, and musical when you’re sculpting tone.

What sets the Env apart isn’t just its size, but its dual-character response. A small toggle switch on the front panel lets you select between linear and exponential envelope shapes. Flip it to linear, and the voltage ramps up or down in a straight line—ideal for controlling filters or VCAs where you want a consistent rate of change. Switch to exponential, and the curve mimics the natural decay of acoustic instruments, giving percussive patches a more organic feel. That choice might seem subtle on paper, but in practice, it’s the difference between a hi-hat that clicks like a metronome and one that breathes like a drummer. The module also outputs a gate signal at the end of the attack stage, which can be used to trigger other events in your system—like clocking a sequencer or resetting an LFO—adding a layer of timing utility you don’t always get in such a compact envelope.

Despite its minimalist faceplate—two knobs, one switch, three jacks—the Env pulls double duty as both a precision tool and a creative voice. CV control over decay time means you can modulate the envelope’s length with an LFO, sequencer, or even another envelope, letting the shape evolve over time. Patch in a slow sine wave and you’ve got an envelope that breathes wider on every cycle; feed it from a random source and the decay times jitter unpredictably, perfect for generative patches. It’s not a full-blown contour generator like a DADSR or looping envelope, but it doesn’t need to be. The Env excels in roles where space is tight and timing is critical: ducking reverb tails, gating noise bursts, or shaping the attack of a plucked string model. It’s the kind of module you install once and forget—until you realize you’re using it on nearly every patch.

Specifications

Manufacturer	2hp
Production Years	2010–2023
Module Type	Envelope Generator
HP Size	2
Depth	34 mm
Power Consumption (+12V)	43 mA
Power Consumption (-12V)	16 mA
Envelope Stages	Attack, Decay
Envelope Shape Options	Linear, Exponential
CV Control	Decay time
Gate Output	End of attack stage
Inputs	Gate, Decay CV
Outputs	Envelope, Gate
Panel Color	Silver anodized aluminum

Key Features

Linear and Exponential Envelope Shapes

The toggle switch between linear and exponential response isn’t just a technical option—it changes the personality of your patch. Linear mode delivers a mechanical, even progression that works beautifully for precise filtering or amplitude control where predictability matters. Exponential mode, on the other hand, gives a softer, more natural decay that’s especially effective on percussive sounds. A snare hit with exponential decay feels rounder, less clicky; a bass note with linear attack cuts through with more authority. The ability to switch between them on the fly means you can audition envelope behaviors without repatching, which is invaluable during live performance or sound design.

Compact Design with Full Voltage Control

At 2HP, the Env is a space-saving marvel, but it doesn’t skimp on functionality. The inclusion of CV over decay time is a thoughtful touch—many ultra-narrow modules omit modulation inputs to save panel real estate, but 2hp kept it in. That means you can dynamically alter the envelope’s length from external sources, turning static shapes into evolving contours. Pair it with a random voltage generator and the decay time stutters and stretches; use a sequencer to step through different decay values and you’ve got rhythmic variation baked into your envelope. It’s a small input, but it opens up a lot of motion.

Gate Output for Timing Chaining

Beyond the main envelope output, the module sends a gate signal at the end of the attack stage. This isn’t just a convenience—it’s a patching multiplier. You can use it to trigger a second envelope, start a delay repeat, or clock a sample-and-hold circuit, effectively turning the Env into a timing hub. In a complex patch, this gate output helps maintain rhythmic coherence across multiple modules, ensuring that events happen in sequence rather than all at once. It’s especially useful in drum synthesis, where you might want the attack transient to trigger a noise burst while the decay shapes the tone.

Historical Context

When 2hp launched the Env around 2010, Eurorack was still in its expansion phase—growing fast, but not yet overcrowded with utility modules. Most envelope generators occupied 6HP or more, with multiple stages, looping capabilities, and digital displays. 2hp took the opposite approach: strip it down, shrink it, and make it fast. The Env was part of a wave of ultra-compact modules that proved small didn’t mean simple. It arrived alongside other 2HP classics like the LFO and VCA, all sharing the same minimalist aesthetic and precision engineering. At a time when skiff builders were counting millimeters, the Env was a revelation—proof that you could have a fully functional, voltage-controlled envelope in less space than a power cable connector.

Competitors like Intellijel and MakeNoise offered more complex envelopes, but none could match the Env’s density. It wasn’t trying to be a Swiss Army knife; it was a scalpel. Its closest analog might be the Doepfer A-140-2, a compact dual envelope, but even that takes up 8HP. The Env carved out a niche for itself in travel racks, DIY builds, and systems where every HP counted. It also influenced a generation of module designers to rethink what “essential” meant—sometimes less really is more, as long as the core circuitry is solid.

Collectibility & Value

The 2hp Env was discontinued in 2023, marking the end of an era for one of Eurorack’s most compact envelope generators. While not rare in the traditional sense—production ran for over a decade—used units in good condition now trade at a premium, especially in silver panel variants. Expect to pay between $120 and $160 on the secondary market, depending on condition and included accessories. Units with original packaging and documentation command a slight bump, but cosmetic wear has little impact as long as the knobs and jacks are functional.

Failures are uncommon, but not unheard of. The most frequent issue reported by technicians is intermittent gate triggering, usually traced to a dirty or failing 3.5mm jack. The module’s compact layout makes repairs tricky—desoldering jacks or ICs requires steady hands and a fine-tip iron—but the circuit itself is robust. No known design flaws or batch defects have surfaced over its production run. Because it draws modest current and generates little heat, power-related failures are rare. The biggest risk for buyers is counterfeits: third-party clones exist, often sold as “2HP-compatible” modules, but they lack the precision response and build quality of the original. Always verify the manufacturer’s logo and panel finish—authentic units have crisp, laser-etched labeling and smooth, anodized aluminum panels.

For new builders, the Env remains a benchmark in efficient design. While newer modules offer more stages or digital control, few match its blend of size, simplicity, and musicality. It’s not the envelope you turn to for complex looping or bidirectional shapes—but it’s the one you reach for when you need something fast, clean, and space-efficient. In a world of ever-expanding modules, the Env stands as a reminder that sometimes, two HP is more than enough.