Sync (2.07MB) Example of two VCOs synced. Master tri to slave sync input. Both vcos
triangle outputs mixed together. slave initially 1 octave above master. sound starts
with no sync, then gradually sync goes from soft to hard. Finally the slave vco course
frequency control is adjusted to produce changes in timbre.
VCO Tuning Procedure:
This is based on the 'Trimmers' section of the User's guide V1.4. I must say that
when I built the VCO Mk1, I was a little baffled about the tuning procedure, and
it took me about an hour to get the thing in tune, and even then, I wasn't sure how
I'd done it. Tony updated the procedures, and included some hints to make things
easier. So here is the procedure I use. It may not be the best way, but it works
for me! First I hook up my keyboard to the MidiDac, then take the pitch output to
the VCO V/Oct input. I use a Fluke 8060A multimeter set to read frequency on the
VCO triangle wave ouput.
1. Turn the HFT to it's minimum setting. To do this, as per the user guide, set
the VCO to play about 3kHz, and turn the HFT trimmer until the pitch starts to drop,
then keep turning until the pot reaches the end of its travels.
2. Play the lowest note on the keyboard and set the VCO COURSE and FINE controls
to give 100Hz.
3. Play a note 2 Octaves above the last and check the frequency. If it's flat, adjust
the V/Oct trimmer to make it flatter still. If it's sharp, then adjust the V/Oct
trimmer to make it sharper still.
4. Play the lowest note again and readjust the COURSE & FINE controls to set 100Hz.
5. Repeat steps 3 & 4 to give a precise 2 octave interval.
1. Play a note 1 Octave from the top of the keyboard and set the COURSE & FINE controls
to give a frequency of 8kHz.
2. Play a note 1 octave above the last and set HFT to give 16kHz.
3. Play the first note again and adjust COURSE & FINE controls to give 8kHz.
4. Repeat steps 2 & 3 to get high frequency interval correct.
Play the lowest note on the keyboard and set the COURSE & FINE controls to give 100Hz,
then recheck for 400Hz, 2 octaves above this.
1. Set the COURSE & FINE controls to middle position and trim TUNE control to match
the frequency to any existing VCOs.