Doepfer A-143-9 QLFO VC Quadrature LFO/VCO

The Doepfer A-143-9 is a voltage-controlled quadrature LFO and sine-wave oscillator capable of generating four phase-related outputs simultaneously. Based around a precision quadrature circuit, it produces exceptionally clean sine and cosine waveforms with very low distortion, making it useful for modulation duties, frequency shifting applications, and experimental audio-rate patching.

The module provides four outputs spaced 90 degrees apart: - Sine (0°) - Cosine (90°) - Inverted Sine (180°) - Inverted Cosine (270°)

These phase relationships make the A-143-9 particularly useful for complex modulation tasks, quadrature effects, panning, rotating control voltages, and frequency shifting applications.

Unlike many sine-wave generators that derive their output from sawtooth or triangle wave conversion, the A-143-9's dedicated quadrature core produces highly accurate sine and cosine signals with exceptionally low distortion.

The frequency range spans from extremely slow modulation cycles lasting several minutes through to moderate audio frequencies in the low kHz range. Three operating ranges are selected via a front-panel toggle switch.

Two frequency control inputs are provided: - CV1 input without attenuation - CV2 input with bipolar attenuator

While the module can operate as an experimental sine-wave VCO, it does not provide precise 1V/octave tracking.

Two front-panel LEDs indicate the positive and negative portions of the sine waveform, providing useful visual feedback when working at low frequencies.

Output amplitude is approximately 5V peak-to-peak (±2.5V) and can be adjusted internally via a trimming potentiometer.

Features

• Voltage-controlled quadrature LFO and sine-wave oscillator
• Four simultaneous phase-shifted outputs
• Sine, cosine, inverted sine, and inverted cosine outputs
• Dedicated low-distortion quadrature oscillator core
• Frequency range from several minutes per cycle to low audio frequencies
• Three selectable frequency ranges
• Two CV frequency inputs
• Bipolar attenuator on CV2 input
• Visual waveform indication via dual LEDs
• Adjustable output level

Specifications

| Specification | Details | |---|---| | Outputs | 0°, 90°, 180°, 270° phase-shifted signals | | Waveforms | Sine, Cosine, Inverted Sine, Inverted Cosine | | Output Level | Approx. 5Vpp (±2.5V) | | Frequency Range | Several minutes per cycle to a few kHz | | CV Inputs | 2 | | 1V/Oct Tracking | No |

• 8 HP 50 mm deep

LFO Oscillator

Found Sound Australia Pty Ltd.
110 Albert St
Brunswick East, VIC 3057
Australia