Doepfer A-147-4 Dual LFO

Doepfer’s A-147-4 is a compact yet versatile dual analog LFO based on the architecture of the A-147-2. Despite its slim 8HP design, the module delivers a rich feature set ideal for both modulation and audio-rate experimentation.

Each of the two LFOs offers five simultaneous waveforms: rising and falling sawtooth, sine, triangle, and a pulse wave with full pulse width modulation. The pulse width can be adjusted manually or modulated via CV, giving you evolving modulation or complex tone-shaping at audio rates.

The CV input for frequency responds to 1V/oct tracking (up to 2.5kHz), making this module suitable for use as a dual utility VCO. The CV polarity switch allows easy attenuation and inversion of modulation sources, while the reset inputs are jumper-selectable for either edge or level response.

Output levels are approximately ±5V (10Vpp), and the square wave output can be jumper-set to either unipolar (0/+10V) or bipolar (-5/+5V). The LFO rate is visually indicated via LED tied to the triangle output.

Each LFO has two selectable frequency ranges via jumpers:

• High range: 0.075Hz (13s cycle) to 1.4kHz

• Low range: 0.007Hz (140s cycle) to 125Hz

The A-147-4 is a powerful modulation source packed into a small footprint—perfect for compact systems or modulation-heavy patches.

• Dual analog LFO in 8HP

• Five simultaneous waveforms: rise, fall, sine, triangle, pulse

• Pulse width modulation via CV

• 1V/oct tracking for use as utility VCO (up to ~2.5kHz)

• CV polarity switch for shaping incoming modulation

• Reset input with jumper-selectable edge/level behaviour

• Output range: ±5V

• Square output switchable to unipolar or bipolar via jumper

• Frequency range LED indication

• Two jumper-selectable frequency ranges

• High build quality from Doepfer