doepfer-a-147-4

Doepfer A-147-4 Dual VCLFO

Dual voltage-controlled LFO with five waveforms and audio-rate capability

8 HP Eurorack module

The A-147-4 is a dual voltage-controlled LFO offering five waveforms per channel — triangle, sine, rising sawtooth, falling sawtooth, and rectangle — with each LFO capable of reaching audio rates up to 2.5kHz for use as a VCO. Its per-channel CV input with attenuator and polarity switch, voltage-controlled pulse width, and resettable triangle core make it a deeply versatile modulation source for rhythmic, textural, and generative patching. The dual architecture allows two independent or interacting LFOs in a compact 8HP footprint.

Features

  • Dual independent voltage-controlled LFOs in 8HP
  • Five waveforms per LFO: triangle, sine, rising sawtooth, falling sawtooth, rectangle
  • Triangle core with derived waveform converters for sine, sawtooth, and rectangle
  • Frequency range selectable via internal jumper: ~0.02Hz-2.5kHz (high) or ~0.0017Hz-220Hz (low)
  • Audio-rate operation up to ~2.5kHz enables use as a VCO
  • Manual frequency control F knob with optional fine-resolution jumper (1:4.5 range restriction)
  • CV input with attenuator knob and three-position polarity switch (positive, off, negative)
  • Factory-calibrated 1V/octave CV sensitivity when CV attenuator is fully CW
  • Optional internal voltage on CV switching contact enables CV knob as fine frequency trim
  • Reset input per LFO, switchable between edge-triggered and level-controlled behavior
  • Adjustable reset start voltage via trimming potentiometer (factory: 0V, adjustable to e.g. -5V)
  • Pulse width manual control and CV input per LFO with combined PW/PM knob

Controls & Jacks (26)

  • LFO 1 Pulse Width / Modulation— Combined control for rectangle pulse width; manually adjusts pulsewidth when P socket is empty, acts as attenuator for external PWM signal w
  • LFO 2 Pulse Width / Modulation— Combined control for rectangle pulse width; manually adjusts pulsewidth when P socket is empty, acts as attenuator for external PWM signal w
  • LFO 2 Pulse Width CV Input— Pulsewidth modulation control voltage input for LFO 2 rectangle output
  • LFO 1 Rectangle Output— Rectangle waveform output from LFO 1; output range (±5V or 0/+10V) selectable via jumper
  • LFO 2 CV Attenuator— Attenuator for control voltage applied to LFO 2 CV input; acts as fine frequency control when no cable is connected
  • LFO 2 Activity— Visual indicator of LFO 2 frequency (triangle waveform)
  • LFO 2 CV Polarity— Polarity switch for LFO 2 control voltage; center position disables external CV modulation
  • LFO 1 Pulse Width CV Input— Pulsewidth modulation control voltage input for LFO 1 rectangle output
  • LFO 1 Falling Sawtooth Output— Falling sawtooth waveform output from LFO 1 (±5V)
  • LFO 2 Rectangle Output— Rectangle waveform output from LFO 2; output range (±5V or 0/+10V) selectable via jumper
  • LFO 2 Rising Sawtooth Output— Rising sawtooth waveform output from LFO 2 (±5V)
  • LFO 2 Frequency— Manual control of LFO 2 frequency; frequency range selectable via jumper (0.075 Hz – 1.4 kHz or 0.007 Hz – 125 Hz)
  • LFO 1 CV Input— Frequency control voltage input for LFO 1; calibrated to 1V/octave when CV attenuator is fully open
  • LFO 1 CV Attenuator— Attenuator for control voltage applied to LFO 1 CV input; acts as fine frequency control when no cable is connected
  • LFO 2 Sine Output— Sine waveform output from LFO 2 (±5V)
  • LFO 2 Falling Sawtooth Output— Falling sawtooth waveform output from LFO 2 (±5V)
  • LFO 1 Triangle Output— Triangle waveform output from LFO 1 (±5V)
  • LFO 1 Frequency— Manual control of LFO 1 frequency; frequency range selectable via jumper (0.075 Hz – 1.4 kHz or 0.007 Hz – 125 Hz)
  • LFO 1 Reset Input— Reset input for LFO 1 triangle waveform; edge-triggered or level-controlled based on jumper setting
  • LFO 1 CV Polarity— Polarity switch for LFO 1 control voltage; center position disables external CV modulation
  • LFO 1 Rising Sawtooth Output— Rising sawtooth waveform output from LFO 1 (±5V)
  • LFO 2 Triangle Output— Triangle waveform output from LFO 2 (±5V)
  • LFO 1 Sine Output— Sine waveform output from LFO 1 (±5V)
  • LFO 1 Activity— Visual indicator of LFO 1 frequency (triangle waveform)
  • LFO 2 CV Input— Frequency control voltage input for LFO 2; calibrated to 1V/octave when CV attenuator is fully open
  • LFO 2 Reset Input— Reset input for LFO 2 triangle waveform; edge-triggered or level-controlled based on jumper setting

How-To Guides

  • Ultra-Slow Ambient Texture Sweep
  • Audio-Rate LFO as Secondary VCO
  • Clock-Synced Rhythmic Gate Source
  • Dual LFO Cross-Modulation
  • Pulse Width Modulated Bass Timbre
  • Reset-Driven Random Slope Generator
  • Stereo Field Animation with Dual LFOs
  • Simultaneous Tremolo and Vibrato
  • Sequencer-Driven Variable LFO Rate

Explore the interactive A-147-4 Dual VCLFO panel on BleepDex — tap any control to learn what it does.

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