2hp Env (2010–2023)

A two-stage envelope that fits in a gap most modules can't reach. It's tiny and precise, and it covers snappy transients and slow morphs.

Overview

Patch a cable into the 2hp Env and the first thing you notice is how little is on the panel. At just 2HP wide, it's one of the narrowest envelope generators ever made for Eurorack, and it doesn't feel like a compromise. Turn the attack knob from fully counterclockwise to full clockwise and the response goes from a near-instantaneous pop to a slow, swelling rise that can stretch over several seconds. That suits ambient pads or filtering in slow motion. The decay does the same on the way down, and it moves smoothly across that whole range. There's no digital stepping and no jitter, just a clean analog glide.

The Env has a dual-character response. A small toggle switch on the front panel selects between linear and exponential envelope shapes. In linear, the voltage ramps up or down in a straight line, which is handy for filters or VCAs where you want a consistent rate of change. In exponential, the curve mimics the natural decay of acoustic instruments, so percussive patches feel more organic. That sounds subtle on paper, but 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. You can use it to trigger other events in your system, like clocking a sequencer or resetting an LFO, which is more timing utility than you usually get in such a compact envelope.

The faceplate is minimal: two knobs, one switch, three jacks. CV control over decay time means you can modulate the envelope's length with an LFO, sequencer, or even another envelope, so the shape evolves over time. Patch in a slow sine wave and the envelope gets wider on every cycle. Feed it from a random source and the decay times jitter unpredictably, which works well for generative patches. It's not a full contour generator like a DADSR or looping envelope. It works best where space is tight and timing is critical: ducking reverb tails, gating noise bursts, or shaping the attack of a plucked string model.

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 changes the personality of a patch. Linear mode gives a mechanical, even progression that works for precise filtering or amplitude control where predictability matters. Exponential mode gives a softer, more natural decay, especially on percussive sounds. A snare hit with exponential decay feels rounder and less clicky. A bass note with linear attack cuts through with more authority. You can switch between them on the fly, so you can audition envelope behaviors without repatching.

Compact Design with Full Voltage Control

At 2HP, the Env is small but doesn't skimp on functionality. Many ultra-narrow modules omit modulation inputs to save panel space, but 2hp kept CV over decay time. That lets you alter the envelope's length from external sources and turn 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 get rhythmic variation built into the envelope.

Gate Output for Timing Chaining

Beyond the main envelope output, the module sends a gate signal at the end of the attack stage. You can use it to trigger a second envelope, start a delay repeat, or clock a sample-and-hold circuit, which effectively makes the Env a timing hub. In a complex patch, this gate output helps keep rhythm consistent across multiple modules, so 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 expanding. It was growing fast, but wasn't yet crowded 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. It arrived alongside other 2HP modules like the LFO and VCA, all sharing the same minimalist aesthetic. For skiff builders counting millimeters, it offered 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 matched the Env's density. Its closest analog might be the Doepfer A-140-2, a compact dual envelope, but even that takes up 8HP. The Env found its niche in travel racks, DIY builds, and systems where every HP counted.

Collectibility & Value

The 2hp Env was discontinued in 2023. It isn't rare in the traditional sense, since production ran for over a decade, but 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 compact layout makes repairs tricky, since desoldering jacks or ICs takes steady hands and a fine-tip iron, but the circuit itself is sturdy. 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. 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. Newer modules offer more stages or digital control, but few match its blend of size, simplicity, and musicality. It's not the envelope for complex looping or bidirectional shapes. It's the one to use when you need something fast, clean, and space-efficient.