Pitch CV Input Test

I've got a lot of irons in the fire at the moment and I can hardly keep up with the blog! Today though I got busy with Lightworks and finished another demonstration video.

Anyway, a week or so ago I hooked up a pitch CV input. The pitch control knob is a simple voltage divider between +15 and -15 volts. Therefore it's approximately 0V when it's centred and tuned.

The vibrato input is a smaller voltage though.

This LFO signal and the tune, detune controls are mixed together to provide a pair of control voltages for the two master oscillators. The vibrato is a balanced alternating current so the pitch swings up and down around the centre level set by the main pitch tuning.
The Vibrato depth control is another voltage divider which sets how much of the Vibrato LFO is added to this mix.
For the external control voltage input I simply inserted a signal in place of the Vibrato LFO.
For this test I needed an LFO and the most convenient tool at my disposal was a Roland Bitrazer. The Roland Aira EFX modules can be customised with an application and various virtual modules are available. All I needed was this LFO.

I used my scope to tweak the levels to match those of the Vibrato LFO and tried it out.

I've added captions so you know what waveforms the LFO is outputting at each point. The adjustments on the Bitrazer itself are to set the depth level of the signal. The other tweaks on the iPad are changing the LFO rate. 

In conclusion, this makes far more versatile vibrato effects possible. It could even be used for pitch bend effects. It's limited by the range of plus or minus one semitone, but that's OK. It's a worthwhile addition.