VCP is a realtime clock augmentation tool for the Korg Volca series. By inputting the Volca clock into a computer, we can then play with the clock and then send it into another Volca. But VCP can also be used in a different mode and instead generate a master clock for the Volcas, which is also useful for a modular synth.

• Modules include: clock divider, clock multiplier, multiplier pulse, swing, swing pulse, skip step, random pass thru, mute, internal metronome, and manual trigger.
• The Mute Line-in & Use Metro will use an internal metronome instead of an external clock source. This is useful if you want to use this Pure Data patch as the master clock source. Or if you don’t have an audio interface.
• The Multiplier Pulse will automatically turn on and off the Clock Multiplier after a set number of beats. The same goes for the Swing Pulse.
• The Metro Sound is useful for listening to the clock source itself, especially since the clock pulse will damage your speakers. It will instead replace the clock pulse with a typical metronome sound. You can also select the metronome time signature by adjusting the Metro Beats Per Bar and therefore affect where the up beat lands.
• Two versions of this patch are available. The GUI version (VCP_GUI.pd and VCP_GUI_core.pd) is optimized for playing and doesn't have clutter blocking your view. The editable version (VCP_Editable.pd) has an understandable signal path and is easier to edit; so you can tweak the settings or add your own module if desired.

It's free and open source. Available for Mac, Windows, & Linux.
http://puredata.info/downloads/pd-extended/releases/0.43.4

• Using an external audio interface
  • Volca Beats (sync out) > Audio input > Computer > Audio output > Volca Keys (sync in)
• Using the built-in sound card of a computer
  • Volca Beats (sync out) > Computer mic input > Computer headphone output > Volca Keys (sync in)
• No audio interface, instead use computer as master clock source
  • Computer (headphones out) > Volca Keys (sync in)

Want to use VCP as the master clock source? You don't need to own a Volca. Just enable Mute Line-in & Use Metro to make VCP an independent clock. This will instead use an metronome within Pure Data and bypass the need for an external clock source. You will probably need a DC-coupled audio interface so that you can output a CV signal from your computer.

1. Open the file VCP_GUI.pd within Pure Data.
2. Checkmark Enable DSP.
   • Without this checkmarked, no input or output audio is possible!
3. It's imporant to confirm that the input device and output device are what you desire.
   • The settings panel can be found in the top toolbar: Media > Audio Settings
4. If you have a line-in signal, turn up View Signal and make sure the the VU meter is moving.
   • This is just to confirm that the Volca clock is actually being received within Pure Data. If you don't see the VU meter moving at all, then your settings probably are not setup correctly either in Pure Data, audio interface, or system settings.
   • If you can see the VU meter moving and yet the yellow box for Input Clock isn't flashing to the beat, then the input signal is too quiet and you should increase the Line-in Level.
5. Check your system output level.
   • If the output signal is too quiet then the receiving Volca won't respond. A good starting point is a volume of 50%.
6. If needed, tweak the Latency Offset.
   • If Pure Data and your audio interface are introducing too much latency, then you might need to purposefully add extra latency. Although counterintuitive, this will effectively push the augmented clock to be only one full step behind, though it is tricky to land precisely. But I suggest you first just start playing and then “tune” this if necessary after seeing how it feels.

Stumbled across a happy accident when creating this tool. I realized that I could have a person actually drive the tempo in realtime. This can be as simple as your hands clapping and using the built-in mic of a Mac laptop. You could also mic the kick drum of a real drum kit and then jam on your synths with a human drummer. Lots of possibilities to explore!