VCV Rack – Modular Synthesizer – Ping Pong Patch

Modules Used in the VCV Rack – Ping Pong Patch

Brand	Module	Function
VCV	MIDI-CV	QWERY or MIDI keyboard input
VCV	VCO-1	Sine Wave Oscillator (sound source for the VCAs)
VCV	ADSR	Envelope Generatior for MIXER
VCV	VCA (left)	Left Channel for MIXER
VCV	LFO-2 (left)	Modulates Amplitude of (left) VCA
VCV	8-VERT	Controls (left) and (right) LFOs
VCV	LFO-2 (right)	Modulates amplitude of (right) VCA
VCV	VCA (right)	Right Channel for MIXER
VCV	MIXER	Takes VCA and ADSR input and sends to AUDIO-8
VCV	AUDIO-8	Sends sound to speakers
VCV	NOTES	Information about the patch

Features of VCV Rack – Ping Pong Patch

1. Take a monophonic source and pan it back and forth in stereo (i.e. ping-pong).
2. Vary the speed of the panning between the left and right stereo channels.
3. Control the the envelope / amplitude of the sound with a trigger from a keyboard or sequencer (i.e. do not want the sound on all the time.).

Feature #1 Detail…

• VCO-1 is the monophonic sound source for this patch.
• The audio output of VCO-1 is sent to both VCAs. In the example patch a sine wave is used. Any waveform can be used.
• (2) VCAs (Voltage Controlled Amplifiers) and (2) LFOs (Low Frequency Oscillators) are used.
• Both LFOs are set to unipolar (0 volts to 10 volts).
• One LFO is set to 0 degrees and the other one is set to 180 degrees.
• You can watch the Ping-Pong effect in the VCA meters.
• The WAVE knob on both LFOs is set full left, which creates a sine wave. This knob can be moved for different effects.
• The FREQ knob is set at the default initialization of 2 hertz.

Feature #2 Detail…

• The 8VERT module is added to the patch to control both LFOs.
• 8VERT is an attenuator that can also reach negative values. VCV call this an “attenuverter”. A hidden feature of 8VERT is when it has no inputs, it acts as a -10 volt to 10 volt, voltage source. This is how the FREQ knobs on both LFOs are controlled and synchronized with the knob on 8VERT.
• The FM CV knob on both LFOs us set all the way to the right which turns the FM input into a 1 volt per octave input. So every 1 volt increase will double the frequency.
• Vary the 8VERT knob to speed up or slow down the ping-ponging effect.

Feature #3 Detail…

• An ADSR (Attack, Decay, Sustain, Release) module, a MIXER module and the AUDIO-8 module are added to the patch.
• The outputs of the two VCAs are sent to the MIXER.
• The ADSR sends a CV (Control Voltage) to the MIXER which controls the stereo output from the MIXER that is sent to AUDIO-8 (which is the audio source for the speakers.

Modifications to the Ping Pong Patch

• Vary the WAVE on the LFOs.
• Offset the FREQ knob on one LFO as compared to the other.
• Use a more interesting waveform on VCO-1. Instead of a sine wave use a SQR (square wave).
• Use a LFO to drive the PWM (pulse width) control on VCO-1.
• Try other signal routing.

Conclusion

Took me awhile to figure out this patch. I used the SCOPE VCV module to the the LFO sine waves out of phase. Discovered the hidden feature of 8VERT to provide a -10 volt to 10 volt control knob.

Using the ADSR to control the MIXER output was a key breakthrough. The meters on the VCAs do a nice job to help visualize the ping-pong effect.