2HP Filt (2016–)
A four-mode analog filter in a panel about as wide as your thumbnail.
Overview
A full multimode analog filter in 2HP shouldn't work, and 2HP built one anyway. Most designs for the same job take 8HP. You plug in a signal, turn cutoff and resonance, and get low pass, high pass, band pass and notch, all available at once. It has no screen and no touch controls, and it won't patch itself for you. It's a plain, useful filter.
The Filt stays clean and precise until you push it. Turn the resonance up and it gives you a resonant squelch that suits acid lines or dubby filter sweeps. Back it off and it smooths harsh waveforms. It isn't modeled after any classic topology you can name - no 12dB Moog ladder, no 24dB Oberheim SEM clone. It's neutral enough to work anywhere, with some character when you ask for it.
In a format where every HP counts, a full multimode filter in 2HP feels like cheating. It's a module you install and then find yourself using on nearly every patch. It isn't the centerpiece of a system, but it's the glue. It can split a drone into its spectral components, pull rhythmic pulses out of noise with band-pass resonance, or carve a frequency hole in a feedback loop with the notch. It's the Swiss Army knife of filtering, minus the flimsy knife and useless toothpick.
Specifications
| Manufacturer | 2HP |
| Production Years | 2016– |
| Original Price | $99 |
| Width | 2HP |
| Depth | 50 mm |
| Power Consumption | 40mA +12V, 39mA -12V |
| Filter Types | Low Pass, High Pass, Band Pass, Notch (simultaneous outputs) |
| Control Voltage Inputs | Cutoff Frequency CV, Resonance CV |
| Manual Controls | Cutoff Frequency knob, Resonance knob |
| Audio Inputs | 1 x Audio In |
| Audio Outputs | 1 x Low Pass, 1 x High Pass, 1 x Band Pass, 1 x Notch |
| CV Inputs | 1 x Cutoff CV, 1 x Resonance CV (normalized to attenuated front panel control) |
| Filter Slope | 12 dB/octave (2-pole) |
| Topology | Analog multimode state-variable filter |
| Self Oscillation | No |
| Color Options | Silver, Black |
| Mounting | Eurorack 3U |
| Weight | Approx. 40g |
Key Features
Four Filters in One, All at Once
Most multimode filters make you choose: low pass today, high pass tomorrow. The Filt gives you all four types - low pass, high pass, band pass and notch - at once, each with its own dedicated output. You can route the same source through all four paths and blend them dynamically, which would take three or four modules otherwise. Send the low-passed fundamental to your main mix, use the band-pass resonance as a percussive trigger, and feed the notch output into a reverb. The outputs are always live.
Minimal Footprint, Maximum Utility
At 2HP wide and 50mm deep, the Filt fits in the "dead zones" - those awkward 2HP gaps between larger modules that usually end up with blank panels or utility attenuators. It also suits skiff builds. The front panel has two knobs, four outputs, two CV inputs and an input. No extras.
Smooth, Musical Response with Voltage Control
The 12 dB/oct slope is gentler than steeper 24 dB designs, so it suits subtle tonal shaping better than drastic timbral surgery. The cutoff knob has a logarithmic taper, and the resonance control adds warmth without getting fizzy or unstable. CV over cutoff lets you sweep the filter for envelope following or LFO modulation, and the resonance CV input gives voltage-controlled intensity. The CV inputs are normalized to the front panel controls, so you can use the knob as an attenuator when patching in modulation. That gives you control over modulation depth without a separate attenuator.
Historical Context
The 2HP Filt arrived in 2016, as Eurorack was shifting from boutique curiosity to mainstream adoption. Pop producers, electronic musicians and bedroom tinkerers were using modular, not just academics and experimental composers. Case space was at a premium, and manufacturers began exploring ultra-compact designs. 2HP, founded by former Doepfer engineer Robin Whittle, had already built a reputation for minimal-space modules - 2HP VCA, 2HP LFO, 2HP ADSR. The Filt was the next step, showing that complex analog circuits could shrink without losing functionality.
At the time, most multimode filters occupied 6HP or more. Mutable Instruments' Steiner-Parker filter (via Braids or later standalone modules) was a favorite, but it took 8HP. MakeNoise's STO was powerful but even larger. The Filt didn't compete on features or raw character. It competed on efficiency. It wasn't the first 2HP module, but it was one of the first to make you ask why anything else took more space. It wasn't a clone or a recreation.
The Filt also fit the rise of "skiff culture" - tiny, portable, ultra-dense cases for on-the-go synthesis. In those cases every millimeter counts, and the Filt was a staple.
Collectibility & Value
The 2HP Filt isn't rare, but it isn't generic either. It's widely available, still in production, and priced at $99. Used units typically sell for $70-$90 depending on condition and color preference (black panels sometimes fetch a slight premium). There's no collector's markup, no scalping and no waiting list.
Failures are rare. The module has no moving parts beyond the potentiometers, and the circuit is simple. The most common issue reported is intermittent audio from the jacks, usually from dust or oxidation, and contact cleaner fixes it. Power draw is modest (40mA/+12V, 39mA/-12V), so it won't tax even the smallest power supplies. There are no known design flaws or batch issues, and no need for modifications.
When buying used, check that all four outputs work and that the CV inputs respond smoothly. Some users have reported slight detents in the knobs, but this is usually just mechanical resistance from the bushings and doesn't affect performance. The module comes in silver or black front panels. The difference is purely aesthetic, though some builders prefer one for visual coherence.
Its collectibility isn’t based on scarcity, but on utility. You don’t collect the Filt because it’s rare; you keep it because you use it. It’s the module that disappears into your setup until you realize you’d have to replace it with three others to get the same functionality. That kind of quiet indispensability is its own kind of value.
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