ALM Busy Circuits Pip Filter
Compact analogue LFO with multi-waveform outputs and VCO mode
4 HP Eurorack module
The Pip LFO is a compact 4HP all-analogue low frequency oscillator with a wide frequency range, voltage control, and multiple simultaneous waveform outputs. It offers both bipolar and unipolar versions of saw, triangle, and sine waves, plus a unipolar square output, and can switch into audio-rate VCO mode with 1V/oct tracking for roughly 5 octaves. Its reset input enables waveform sync and hard sync in VCO mode, making it versatile for modulation, drone synthesis, and rhythmic patching.
Features
- All analogue oscillator circuit
- 4HP compact form factor
- LFO frequency range approximately 0.01Hz to 30Hz
- VCO mode with audio-rate operation and ultrasonic range
- 1V per octave tracking over approximately 5 octaves in VCO mode
- Simultaneous square, saw, triangle, and sine wave outputs
- Bipolar (+/-5V) and unipolar (0-5V) outputs for saw, triangle, and sine simultaneously
- Unipolar square output at 0-8V
- FREQ knob for manual frequency setting
- CV input for voltage-controlled frequency modulation
- RESET trigger input resets all waveform cycles
- Hard sync functionality via RESET in VCO mode
Controls & Jacks (20)
- Reset — LFO reset trigger input. Resets all waveform cycles; acts as hard sync in VCO mode.
- Frequency 1
- Saw Output Bipolar — Bipolar sawtooth wave output oscillating between -5V and +5V.
- Saw Output Unipolar — Unipolar sawtooth wave output oscillating between 0V and +5V.
- Square Output — Unipolar square wave output at 0-8V.
- Freq CV Input — CV input for voltage control of LFO frequency.
- Frequency 2 — Manual LFO frequency setting control. Frequency range approximately 0.01Hz (90s cycle) to 30Hz (0.03s cycle) in LFO mode, or audio range in
- Triangle Output Bipolar — Bipolar triangle wave output oscillating between -5V and +5V.
- ▼Res
- FREQ — Manual LFO frequency setting control. Frequency range approximately 0.01Hz (90s cycle) to 30Hz (0.03s cycle) in LFO mode, or audio range in
- VCO MODE — Toggles VCO mode. When engaged (indicated by associated LED), the LFO operates at audible frequency range and tracks 1 volt per octave rough
- FREQ CV — CV input for voltage control of LFO frequency.
- RST — LFO reset trigger input. Resets all waveform cycles; acts as hard sync in VCO mode.
- Square Out — Unipolar square wave output at 0-8V.
- Saw Out Bipolar — Bipolar sawtooth wave output oscillating between -5V and +5V.
- Saw Out Unipolar — Unipolar sawtooth wave output oscillating between 0V and +5V.
- Triangle Out Bipolar — Bipolar triangle wave output oscillating between -5V and +5V.
- Triangle Out Unipolar — Unipolar triangle wave output oscillating between 0V and +5V.
- Sine Out Bipolar — Bipolar sine wave output oscillating between -5V and +5V.
- Sine Out Unipolar — Unipolar sine wave output oscillating between 0V and +5V.
How-To Guides
- Slow Ambient Filter Sweep
- Analogue Drone Bass
- Hard Sync Growl
- Tremolo Effect
- LFO as Clock Source
- Vibrato Pitch Modulation
- Sample-and-Hold Randomness
- Complex Waveform Blending
- Tempo-Synced LFO Reset
- Calibrating V/Oct Tracking
Explore the interactive Pip Filter panel on BleepDex — tap any control to learn what it does.
