2HP VCO (2010s–present)

Name: 2HP VCO
Brand: 2HP

It shouldn’t sound this rich in two horizontal inches—but plug it in, twist the tiny knob, and suddenly you’re swimming in CEM3340 magic.

Overview

There’s a moment when you first fire up a 2HP VCO that feels like a prank on physics. The module is so narrow—just two horizontal Eurorack units, skiff-friendly depth, barely wider than a patch cable—that you half expect it to squeak or wheeze. Instead, what pours out is a full-bodied, harmonically rich analog tone that punches way above its size class. This isn’t some digital approximation or minimalist waveform generator; it’s a real, honest-to-goodness CEM3340-based analog oscillator, resurrected from the golden era of polysynths and packed into a space so small it defies belief. The sound? Thick, warm, and startlingly musical, with a character that harks back to the Prophet-5 and Oberheim OB-X, yet with a clarity that cuts through dense patches. It’s the kind of oscillator you reach for not because you’re out of space, but because it simply sounds good—really good.

Positioned as the spiritual successor to 2HP’s earlier OSC module, the VCO refines the concept with tighter tracking, improved stability, and a more robust set of features. Where the OSC was charming but occasionally temperamental, the VCO feels like a grown-up version—still tiny, still efficient, but now with the kind of 1V/oct tracking across 10+ octaves that makes it viable for melodic leads, basslines, or FM experimentation. It’s not trying to be a feature monster. There’s no wavetable scanning, no digital effects, no microtonal tuning wizardry. What it does, it does with focus: generate triangle, sawtooth, and square waves, all simultaneously available, all analog, all with a purity that belies its footprint. The square wave has that crisp, slightly hollow edge perfect for pulse-width modulation, while the sawtooth carries a rounded aggression that never turns harsh. The triangle? Smooth, fundamental-rich, and ideal for sub-bass or LFO duties when dropped into low frequencies.

And yes, it goes down to LFO rates—slowly, smoothly, without stepping or jitter. That’s no small feat in a module this compact, where power regulation and thermal stability can make or break low-frequency performance. But the VCO pulls it off, making it a dual-purpose workhorse: a lead oscillator by day, a modulation source by night. Pair it with another VCO for FM, sync it to a digital beast for metallic clangs, or use it as a drone generator—the flexibility is baked in. It’s the kind of module that makes you rethink what “utility” means. This isn’t just a spare oscillator for when you run out of space; it’s a sonic asset, a character generator, a tiny titan in a sea of bulkier competitors.

Specifications

Manufacturer	2HP
Production Years	2010s–present
Original Price	$134
Width	2HP
Depth	42mm
Power	+12V: 27mA, -12V: 24mA, 5V: 0mA
Oscillator Type	Analog VCO
Core Chip	Curtis CEM3340 (reissue)
Waveforms	Triangle, Sawtooth, Square
Outputs	Simultaneous triangle, sawtooth, square
FM Input	Linear FM
Sync Input	Hard Sync
PWM Input	Pulse-width Modulation control
Tracking	10+ octaves, 1V/Oct accurate
Color Options	Silver, Black

Key Features

The CEM3340 Resurrection

The heart of the 2HP VCO is the reissued Curtis CEM3340 chip—a piece of silicon revered by analog synth purists for its rich, stable, and harmonically complex output. Originally found in classics like the Sequential Circuits Prophet-5 Rev 2 and the Oberheim Matrix series, the CEM3340 fell out of production for decades, becoming a sought-after relic. When it was finally reissued, builders like 2HP seized the opportunity to bring its magic into the Eurorack format. The result here is a tone that’s both vintage and immediate—warm without being muddy, bright without being brittle. It’s the kind of oscillator that doesn’t need effects to sound interesting; even a raw triangle wave has presence, depth, and a slight organic wobble that feels alive. This isn’t just about nostalgia; it’s about having access to a specific analog character that many modern designs either can’t replicate or choose not to pursue.

Minimal Footprint, Maximum Function

At 2HP wide, the module is essentially a footprint experiment made real. Most oscillators in this category either sacrifice features or sound quality to save space, but the VCO refuses to compromise. It delivers three clean, simultaneous waveforms, linear FM, hard sync, and PWM—all without skimping on tracking or stability. The front panel is stripped to the essentials: a single tiny knob for coarse tuning, a minuscule push-button for fine-tuning (adjusted via a small screwdriver), and jacks for CV, FM, sync, and outputs. There’s no display, no menu diving, no digital tricks—just voltage in, sound out. This minimalism isn’t a limitation; it’s a design philosophy. It forces you to think about patching, about modulation sources, about how this oscillator interacts with the rest of your system. And because it’s so small, you can afford to have more than one. Stack three for a compact unison lead, or dedicate one solely to FM modulation without guilt.

Trim Pots and Hidden Depth

Beneath the surface, the VCO offers a level of tweakability that surprises given its size. The circuit board houses multiple trim pots—adjustable with a small screwdriver—that allow for fine calibration of pitch tracking, triangle wave symmetry, and sine wave shaping (yes, despite no dedicated sine output, the triangle can be adjusted to approximate a sine). These aren’t just factory-set tweaks; they’re user-accessible, inviting hands-on calibration. Documentation from 2HP confirms that one trim pot handles 1V/oct calibration, while others adjust waveform symmetry and roundness. This level of control means the module can be dialed in for perfect tracking across your system, or subtly voiced to taste. It’s a nod to the DIY ethos of modular synthesis—this isn’t a sealed black box, but a living circuit you can shape.

Historical Context

The 2HP VCO emerged during the mid-2010s Eurorack boom, a time when skiff-builders and minimalists were pushing back against the trend of ever-larger, feature-packed modules. While companies like MakeNoise and Mutable Instruments were exploring complex digital-analog hybrids, 2HP carved a niche by asking: how small can a real analog oscillator be? The answer, it turned out, was “two HP.” This wasn’t just an exercise in miniaturization—it was a statement about efficiency, accessibility, and sonic integrity. At a time when Eurorack prices were climbing and cases were filling up, the VCO offered a way to add genuine analog oscillation without sacrificing real estate. It stood in contrast to both the bloated “do-it-all” modules and the wavefolding digital oscillators that dominated the budget end. Instead, it leaned on proven analog architecture—the CEM3340—to deliver a sound that felt both classic and fresh. Competitors like the Intellijel Dixie or the Noise Engineering Loquelic Iteritas offered more features, but none could match the VCO’s space-to-sound ratio. It wasn’t trying to win a spec sheet war; it was solving a real problem for rack builders: how to keep the analog heart beating in a shrinking world.

Collectibility & Value

Today, the 2HP VCO trades in a narrow but consistent range—typically between $120 and $160 on the used market, depending on condition and color. Silver and black versions are equally common, with no significant price difference between them. Unlike some boutique modules that inflate in value, the VCO remains accessible, thanks in part to ongoing production and 2HP’s commitment to fair pricing. That said, it’s not a module that depreciates into obscurity. Its reputation for reliability and tone ensures steady demand, especially among skiff users and minimalist builders. Units in working order with stable tracking are the norm, but there are a few failure points to watch for. The most commonly reported issue—though rare—is drift in 1V/oct tracking over time, often tied to aging components or inadequate warm-up. Some users have reported the need to recalibrate trim pots after extended use, particularly in systems with unstable power supplies. The tiny front-panel knob and push-button tuning system can also be fragile; excessive force may damage the potentiometer or underlying PCB traces. When buying used, test tracking across multiple octaves, check for waveform symmetry, and ensure FM and sync inputs respond cleanly. Recapping isn’t a common requirement yet, but service technicians note that early units may benefit from it if drift becomes persistent. Overall, the VCO is considered low-maintenance and robust—more “set and forget” than “constant tweaking.” It’s the kind of module you buy once and keep, not one you flip for profit.