DOEPFER / A-147-2V VCD LFO

Variations

This module is made by the German synthesizer manufacturer Doepfer. The A-147-2 VCDLFO is an LFO module composed of three subunits.

The A-147-2 VCDLFO is an LFO module composed of three subunits. It is the successor to the A-147 VCLFO, but with significantly more features. The A-147-2 consists of the following subunits:

VC LFO: CV-controllable LFO.

VCA: CV-controllable amplifier. Switchable to VC polarizer.

VC Delay: CV-controllable linear attack envelope (envelope with only attack parameter). Combined with the LFO and VCA, it can produce delayed vibrato and tremolo.

VC LFO:
The LFO features CV-controllable triangle, sine, sawtooth, and square waves, and includes Reset/Sync In. The LFO's operation can be visually confirmed with dual-color red and green LEDs for the triangle, sine, and square waves, and a single-color blue LED for the sawtooth wave. The output levels are -4V to +4V for triangle, sine, and square waves, and 0V to +8V for sawtooth waves.

The CV Mode switch allows you to switch between attenuator and polarizer control. In attenuator mode, a constant voltage is output at the 0 position; turning it to the right increases the LFO amplitude in the positive direction. In polarizer mode, a constant voltage is output when the knob is in the center position. Turning it to the right from the center acts like an attenuator, and turning it to the left from the center increases the amplitude in the negative direction. Without external CV input, the frequency range is 0.005Hz (one cycle in 3 minutes) to 200Hz. An internal jumper can be set to switch to ultra-low frequency mode. Setting this jumper connects a fixed voltage to the LFO CV socket. Polarizer mode allows operation at extremely low frequencies (one cycle of 1 hour or more).

VCA
This is a CV-controllable linear VCA. The VCA Mode switch allows you to switch between a normal VCA and a VC polarizer.

The A-147-2 VCA has three inputs and outputs. Of the jacks on the panel, the three vertical columns on the right—In (Signal In), Out (Signal Out), and CV (Control Voltage In)—are the VCA's inputs and outputs. Normally, the VCA In is internally connected to the VC LFO's triangular wave Out, and the CV is internally connected to the Delay Out. However, connecting a cable disconnects these internal connections. This allows you to use the VCA independently of the VC LFO and VC Delay.

VC Delay Unit
This is a VC envelope generator with only one parameter: Delay (or Attack). Upon receiving a signal at Delay Reset, it generates a voltage that increases linearly from 0V to +5V. The voltage remains at +5V until the next Delay Reset is received. The green LED on the Delay Out jack provides visual confirmation of operation.

Width: 8HP
Depth: 55mm
Current Consumption
+12V: 60mA
-12V: 40mA