adjusting scaling...

[List, Chris]

Troy - 

If I understand correctly, you're asking "what's your method for
adjusting the v/oct trimmer". 
- Yes?

Here's what I do...
1. Play a low note on my reference synth (ref-VCO) so that pitch CV = 0v
out for my midi->CV converter...
2. Set the pitch of the modular VCO (mod-VCO) to match (using course /
fine tune)
3. Play a note about three octaves up on the ref-VCO
4. If the VCOs are in tune - or in tune enough that you can't notice a
difference, goto step (8).
5. Tune the mod-VCO to match the pitch of the ref-VCO (using course /
fine tune) paying careful attention to whether you have to tune up or
down to get them together.
6. Adjust the v/oct trimmer. Turn the trimmer so that it causes the
pitch of the mod-VCO to go in the <<opposite direction>> from the way
you tuned it in step (5). The amount to adjust it should be proportional
to the amount it was out of tune, but will always cause a much smaller
difference in the pitch. In fact, as you start getting close to proper
tracking, you'll be turning the trimmer by such small amounts that you
won't be able to hear the pitch change, so you'll need to learn which
direction to turn the trimmer to make the pitch go up vs. down. The
amount to turn takes practice to find and is VCO and trimmer dependant -
if you find yourself going back and forth with the direction on each
pass, then you're turning it too far!
7. Go back to step 1.
8. Play a note one or two octaves higher (4 or 5 octaves over your
original note)
9. If the notes are still in tune between the two VCOs, you're done!
Otherwise, go back to step (5).
Out of tune condition is easier to hear with bigger gaps between the
notes, but the adjustments are much finer, so I save that until I know
I'm close.

Hope that helps, it works well for me. I'm actually not sure if it will
work for any VCO, but it's worked on all the ones I've tried it on...
and once you get a feel for how far you have to adjust the trimmer, you
can do it pretty quickly...

- CList

> -----Original Message-----
> From:	Troy Sheets [SMTP:tsheets at saturn5.com]
> Sent:	Monday, October 20, 1997 2:21 PM
> To:	synth-diy at horus.sara.nl
> Cc:	analogue at hyperreal.org
> Subject:	adjusting scaling...
> 
> 
> I am looking for advice on the best way to adjust keyboard scaling
> on my synths.  Should I tune the highest notes first, then go to the
> lowest notes and adjust scaling?  Or vice versa?  Any tips
> will be apperciated.
> 
> thanks,
> -troy
> 
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