Analogue Solutions Concussor - Manual (Page 31)

ANALOGUE SOLUTIONS
CONCUSSOR e&oe (c) 12-2007 31
VCO Calibration
It is fairly easy to tune in the VCO to another sound as you just have to alter the front panel VCO Tune control. There
may be instances though were the octave spacing (scaling is out). The VCO could go out of tune as you play up the
keyboard. As mentioned earlier, this does not neccessarily mean the VCO itself is at fault. The VCO responds to 1V per
octave, it could be the control source is not giving out exactly 1V per Octave.
With most control sources the output scaling can be altered. This is the case with all MIDI to CV converters. It is
better and far easier to alter the output scaling of the source than the scaling of the VCO.
If you do need to calibrate the VCO scaling for some reason follow the guide lines below:
Firstly, adjusting the trimmers inside the VCO may result in you voiding your warranty. Electrical safety (to your self
and to the module) must be obsereved. If you are not 100% confident and competant - do not attempt!
You will need to let the VCO circuits to ‘warm up’ for a period of time. I usually leave the systems on for 30 minutes
to allow all the analogue ciruits to settle.
VCO: Turn Glide zero. Set the Tune pot to centre.
Connect a MIDI to CV converter to the VCO Pitch CV in. The MIDI keyboard you use to control the VCO will need
to have audio too so you can tune the VCO to your MIDI keyboard.
On the VCO circuit board are 2 trimmer pots. Tune and Scale.
1/ Play a low key on the MIDI keyboard. Adjust Tune so that the VCO is in tune with the MIDI sound source.
2/ Play a high key (about 3 octaves up). Adjust the Scale so that the VCO is in tune with the MIDI sound source.
3/You will need to repeat steps 1 and 2 several times till tuning is spot on.
Your VCO should now be tuned to the outputs of your MIDI to CV converter.
Note, unless your MIDI to CV converter is also setup correctly, the VCO may sound out of tune when played with
another CV source.
For details on how to use your MIDI to CV converter, contact the manufactuer, not us!
Oscillator Sync
The familiar and favourite oscillator sync sound is achieved by using two oscillators. One is the master oscillator
and each time it begins a new wave cycle, it will reset the slave oscillator. Full details of the ins and outs of osc sync
can be found various web resources.
To get this feature working on the VCO
• patch a 2nd VCO’s waveform out into the 1st VCO's Sync In
• Take your main audio out from the 1st VCO (this is where your sync sound will be)
• To control the Sync effect, control the either VCO's pitch.
Note; it is important to balance the relative pitches of the 2 oscillators to get an effective sound. With certain settings
you may not get an effect or even any audio!