ALM Busy Circuits Pip Filter

Compact Low-Pass Filter and VCA for Eurorack

• 2-pole low-pass filter (12 dB/oct) and VCA in just 4 HP
• Manual resonance up to self-oscillation
• Two CV inputs for cutoff: one with an attenuverter, one with approximate V/oct tracking
• Trigger input for filter pinging and plucked percussive sounds
• Integrated open-normed VCA for optional amplitude control
• Suitable for skiff cases, 2-year warranty, made in England

The ALM Busy Circuits Pip Filter is a voltage-controlled 2-pole low-pass filter with resonance, a trigger input for pinging, and an integrated VCA—all packed into just 4 HP. It’s the ideal solution when space in your case is limited but you want to enhance a voice with a filter and amplitude control, or add a small percussive sound generator to your Eurorack system.

2-pole low-pass filter with resonance in 4 HP

At the heart of the Pip Filter is a 12 dB/oct low-pass filter with a smooth, musical slope that allows harmonics to breathe without cutting them off too sharply. The cutoff can be adjusted via the knob and two CV inputs: the first features a built-in attenuverter to control modulation—even in the negative range—while the second offers approximate V/oct tracking to follow the pitch of the notes.

Resonance up to self-oscillation

Resonance is manually controlled and can be pushed all the way to self-oscillation. In this state, the filter generates a sine wave that, thanks to the V/oct input, roughly follows the keyboard or sequencer: an additional sound source for pure bass tones, drones, and minimalist lines.

Pingable filter for percussive and plucked sounds

The trigger input allows you to excite the filter with a pulse, a technique known as “pinging.” With high resonance, each trigger produces a short, resonant sound with a plucked or percussive character: kicks, toms, woodblocks, and plucks can be achieved without additional oscillators or envelopes.

Integrated VCA for complete control over the voice

The built-in VCA, which is open by default, passes the filtered signal when nothing is connected to its input. By sending an envelope or an LFO to the VCA, you gain independent amplitude control, integrating the oscillator, filter, and amplifier chain into a single compact module.

Technical Specifications

• Brand: ALM Busy Circuits
• Model: Pip Filter
• Type: Low-pass filter and VCA for Eurorack
• Filter: 2-pole low-pass, 12 dB/oct, with resonance
• Cutoff: manual control and 2 CV inputs (one with an attenuverter, one with approximate V/oct tracking)
• Resonance: Manual control up to self-oscillation
• Trigger input for filter pinging
• Integrated VCA with open-normed input
• Power supply: +12 V 25 mA, -12 V 25 mA
• Dimensions: 4 HP
• Depth: 32 mm, suitable for skiff cases
• Reverse polarity protection
• Warranty: 2 years
• Made in England