Hi Gur:
I also use the method Dave recomends (below) for scaling your VCOs. The only
caveat being that if you use a sine wave on the VCO you are scaling, and are
comparing it to a complex waveform (i.e., saw, pulse, tri), you may find
you're rescaling (incorrectly!) your VCO around the 4th or 5th octave. I've
been finding myself doing this recently since one of these harmonics (4th?,
5th?, 6th? -- to lazy to look it up now) is actually close to a minor 7th
which is so close to the octave that it can fool you into rescaling too much.
Has anyone else experienced this?
JB
In a message dated 5/14/99 6:58:35 AM,
daveb@... writes:
>You really don't need a freq counter or strobe tuner or oscilloscope or
>DVM
>
>to set tracking on these babies!
>
>
>
>It's really easy to do by ear! These are the easiest VCOs to set tracking
>on
>
>that I've ever seen. All you need is a second VCO, either MOTM or from
>any
>
>other source, as long as it can just sit there and not drift.
>
>
>
>1. Set up your reference oscillator to play a sawtooth at about 125 Hz
>(one
>
>octave below middle C, exact pitch does not matter at all). It should not
>be
>
>connected to any keyboard voltage or modulation, you just want a straight
>
>steady tone. I find it easier to set the tone to play continuously, either
>
>by turning up the initial VCA gain or, if it is an external VCO from some
>
>other synth, prop the key down with something.
>
>
>
>2. Hook your MOTM-300 to your midi/cv source, and use a sawtooth. You should
>
>have already set the trimmer to approximately its center range as the VCO
>
>instructions told you to. Make both oscillators the same loudness. Don't
>
>play so loud that you cause other things in the room to rattle, etc. Play
>
>one octave below middle C on the keyboard, and tune the MOTM exactly to
>the
>
>same pitch as the other VCO using Coarse and Fine controls. When the pitch
>
>is very close, you hear "beats" between the 2 pitches. When it is in tune,
>
>you hear none.
>
>
>
>3. When they are perfectly in tune, play a note one or two octaves higher
>
>and you should hear that the VCO is either somewhat sharp or flat. Turn
>the
>
>Fine tune up or down until it is in tune again. If you had to turn Fine
>
>clockwise, it was flat, and you will need to turn the trimmer clockwise
>a
>
>little bit. If you had to turn Fine CCW, it was sharp, and you have to
>turn
>
>the trimmer CCW some.
>
>
>
>4. Now play the low note again, and retune the MOTM so that it is perfectly
>
>in tune (no beats), and repeat steps 3 and 4 to refine your tuning until
>you
>
>zero it in.
>
>
>
>5. You can continue to refine this by playing a wider interval. I generally
>
>stop after about 4 octaves.
>
>
>
>Repeat for all VCOs, setting up 1 as the drone and one for calibration.
>
>Easy! It should not take you more than 5 to 10 minutes per VCO.
>
>