2hp EG (2008–Present)

Name: 2hp EG
Brand: 2hp

Two knobs, two stages, and a time range so vast you’ll question if your patch is frozen or evolving.

Overview

You twist the attack knob clockwise and your envelope stretches from a snappy 3 milliseconds into something that feels geological—11 minutes of rise time, creeping like fog across a shoreline. That’s the 2hp EG in motion: a minimalist two-stage envelope generator that punches way above its weight in a Eurorack case. At just 2HP wide, it’s skiff royalty, the kind of module you install not because it looks flashy, but because it quietly enables patches that would otherwise demand three times the real estate. It doesn’t pretend to be an ADSR—there’s no sustain stage, just attack and decay—but within that simplicity lies a kind of brutal elegance. You get linear or exponential curve selection on the fly, CV control over both time parameters, and a built-in attenuator on the output that doubles as a manual level knob. It’s not trying to be everything; it’s trying to be essential.

And it succeeds, mostly. The EG’s range is its headline feature, and deservedly so. Need a percussive blip for a kick drum? Crank it down. Want a slow filter sweep that unfolds over several minutes, transforming a drone from ice to fire? This module breathes at that pace. The ability to switch between linear and exponential curves mid-patch adds expressive flexibility—exponential for natural-sounding decays, linear for clocked precision or metallic zaps. But it’s not without quirks. Some users report a slight volume drop when using the EG to control amplitude directly, especially when paired with certain VCAs. It’s not a design flaw per se, but more a consequence of its minimalist signal path and the expectations of modern modular users who assume perfect unity gain. The knobs, while functional, have been described as wobbly or cheap-feeling, a trade-off for the ultra-slim front panel. It’s the kind of thing you notice when you’re knee-deep in cabling and reach for a quick adjustment—your finger slips, the patch shifts, and you wonder if it was worth saving that one HP after all.

Still, the EG’s value isn’t just in its specs. It’s in its role as a Swiss Army knife for timing. Use it as a gate delay, a slow LFO substitute, a trigger stretcher, or even a rudimentary sequencer when patched into a comparator. Its attenuator isn’t just for scaling CV—it lets you manually offset the envelope’s peak, useful for shaping filter sweeps without touching your keyboard. It’s the module you reach for when you want to add motion without clutter, when your case is full but your patch feels static. In a world of bloated, feature-saturated envelopes, the 2hp EG is a reminder that sometimes two stages are enough—if they go deep enough.

Specifications

Manufacturer	2hp
Production Years	2008–Present
Original Price	$97 USD
Width	2HP
Depth	42 mm
+12V Current Draw	26 mA
-12V Current Draw	7 mA
Envelope Type	Two-stage (Attack/Decay)
Time Range per Stage	3ms to 11 minutes
Curve Selection	Linear and exponential (switchable)
CV Control	Attack and Decay (normalled to attenuated inputs)
Attenuator	Integrated output attenuator with manual control
Inputs	Gate/Trigger, Attack CV, Decay CV
Outputs	Envelope CV
Module Type	Eurorack Envelope Generator
Front Panel Material	Aluminum

Key Features

Time Range That Defies Practicality (And That’s the Point)

The 2hp EG’s most talked-about feature isn’t just its wide time range—it’s how absurdly wide it is. From 3ms to 11 minutes per stage, it spans the gap between human reflexes and geological time. In practice, this means you can use it for anything from tight snare transients to glacial ambient swells that evolve over entire tracks. The lower end is crisp and reliable, perfect for rhythmic modulation, while the upper end opens doors to experimental sound design. Patch it into a filter cutoff and let a single note bloom over five minutes. Use it to modulate a wavefolder’s intensity so subtly that the change is almost subconscious. The range isn’t just a spec sheet flex—it’s a compositional tool. And because both attack and decay are CV-controllable, you can dynamically shift the envelope’s character in real time, morphing from staccato to legato with a single control voltage.

Minimalism as a Design Philosophy

At 2HP, the EG is a triumph of minimalism. Every millimeter counts in Eurorack, and this module respects that. There are no flashy displays, no multiple outputs, no loop modes or retrigger options. Just two knobs, a switch, and a handful of jacks. The front panel is clean, almost austere, with tactile but basic controls. The attenuator doubles as a manual output level knob, eliminating the need for a separate attenuator module in simple patches. This kind of integration is where 2hp’s design shines: it’s not just small, it’s efficient. The lack of a sustain stage might seem limiting, but in many patches—especially drum voices or one-shot effects—an AD envelope is all you need. It’s the modular equivalent of a well-placed haiku: few words, maximum impact.

Curve Switching for Expressive Shaping

The ability to switch between linear and exponential curves on the fly is more than a convenience—it changes the character of your sound. Exponential curves mimic natural decay, making them ideal for emulating acoustic instruments or creating smooth, organic fades. Linear curves, on the other hand, offer mechanical precision, perfect for rhythmic modulation or digital-sounding effects. The switch is small but decisive, and it’s normalled to exponential, which means if you leave it unpatched, you’re getting the warmer, more musical response by default. This kind of thoughtful default behavior speaks to 2hp’s user-centric design: it assumes you want musicality unless you say otherwise.

Historical Context

The 2hp EG emerged in the late 2000s, just as Eurorack was transitioning from niche curiosity to mainstream synth culture. At the time, module widths were still relatively generous—8HP, 10HP, even 16HP wasn’t uncommon. 2hp, founded by Tony Rolando (also behind the original Buchla 200e firmware), challenged that norm with a line of modules built around extreme space efficiency. The EG was one of their early standouts, proving that you didn’t need a sprawling panel to deliver serious functionality. It arrived alongside other minimalist pioneers like Intellijel’s µ-series and Make Noise’s tiniest utilities, but stood out for its sheer range and thoughtful integration of an attenuator. Competitors like Doepfer offered ADSRs with more stages, but none matched the EG’s time span in such a narrow footprint. It wasn’t trying to replace those modules—it was offering an alternative for cases already bursting at the seams. In an era where modular was becoming synonymous with excess, the EG was a quiet argument for restraint.

Collectibility & Value

The 2hp EG has never been a “collector’s item” in the traditional sense—no limited runs, no special editions, no cult mythology around its design. It’s too common, too utilitarian for that. But its value lies in its ubiquity and reliability. As of 2024, new units sell for around $97, unchanged from its original price for years, a rarity in the modular market. Used units typically go for $60–$80 depending on condition, with little fluctuation. There are no known production runs or revisions to track—just a steady stream of consistent builds. Failures are rare, but when they occur, they’re usually power-related or tied to the switch mechanism for curve selection, which has a small but noticeable failure rate over time. The knobs, while functional, are a common complaint: they feel loose and can wobble under frequent use, though they rarely fail outright. For buyers, the main advice is to test the switch and both CV inputs—make sure the curve selection clicks cleanly and that CV modulation responds smoothly across the full range. There’s no need to recap or refurbish these units; they’re solidly built for their price point. If you’re building a case and need a no-frills, space-saving envelope, the EG remains one of the most cost-effective choices out there—especially if you value that colossal time range.