DOEPFER / A-147-5V QuadVC LFO

Variations

The A-147-5 is a module with four CV-controllable LFOs (VCLFOs) with triangular wave output.

All LFOs share a common frequency control; LFOs 2/3/4 each have a delta (Δ) knob that can be used to adjust their respective frequencies up or down relative to the reference frequency; when the delta knob is set to the center position, all LFO frequencies are approximately the same. The LFO frequency can be controlled by an external CV. A CV input terminal is provided to control the frequency with an external CV, and is roughly compliant with 1V/Oct.

Example of use
Generates four triangular wave modulation signals with a common frequency control for all LFOs and individual controls for frequency adjustment of each LFO that can also be controlled by external CV.

Generate modulation signals for polyphonic FM/PWM patches by connecting the control voltage source used for the pitch CV input of the VCO corresponding to the A-147-5 to the respective CV input of the A-147-5. This will control the frequency of each LFO according to the changing frequency of the associated VCO. The frequency (F knob) and frequency deviation (ΔF knob) of all VCOs can be controlled. The Quad VCA module A-130-4 is recommended for controlling the depth of these modulations.

Generates complex modulation signals by summing the output.

Controls
F control knob : manually controls all 4 LFO frequencies
Delta F2 ~ 4 control knob : manually controls shift up/down of any LFO frequency
Input/Output
CV 1 ~ 4 : frequency CV input (internally wired in descending order from CV 1 to CV 4)
Triangular wave output 1 ~ 4 : Triangular wave output terminals
LED : Indicates triangular wave output status (red = positive phase, yellow = negative phase)
Features
Triangular wave output level is approximately +/-5V (10Vpp).
The manually adjustable frequency range is from about 0.025 Hz (about 40 seconds) to about 50 Hz with the LFO 2, 3, and 4 delta control knobs in the center position.
The frequency deviation that can be adjusted by the delta knob is approximately ±1:5. Example: If the center position is 1 Hz, the frequency shift range is from about 0.2 Hz (knob at -5) to about 5 Hz (knob at +5). (1Hz/5 = 0.2Hz, 1Hz*5 = 5Hz)
Manual frequency control with the knob and CV input works exponential.
The maximum frequency when using external CV is approximately 150 Hz.
The scale of the CV input is roughly in accordance with 1V/Oct. (Not adjustable)
The CV inputs are internally wired in descending order from 1 to 4. When only CV1 is patched, CV1 controls the frequency of all four LFOs.
If each CV input pin is patched to its own voltage source, each LFO frequency is controlled individually. So in this case, the CV1 input controls only the frequency of LFO 1.
The board provides four terminals for four triangle wave outputs for internal connection to other modules (when using polyphonic modulation, the A-130-4 is routed through the A-111-4). Four square wave outputs are available on the board section (+/-10V, 20Vpp). To avoid short circuits, the use of a 1k protection resistor is recommended. If lower levels are required, use a passive attenuator (voltage divider). Triangular wave sum signals (un-buffered) can also be used. In this case, each of the four triangle outputs is simply connected to the sum output pin via a 47k resistor. Because of the high impedance of these outputs, they should be buffered or amplified (e.g., A-180-3, A-180-4, A-183-3, etc.) to avoid level drops when the load changes.
By changing the value of the capacitor in the LFO circuit, outputs in other frequency bands are possible (e.g., from a Quad VCO to a kind of “cloud VCO”). The 1V/oct scale is not adjustable.

Width 4HP
Depth 45mm
Current consumption
+12V : 30mA
-12V : 30mA