[sdiy] Thoughts on a Polyphonic Synth

[Antti Huovilainen]

On Fri, 24 Mar 2006, Tom Arnold wrote:

> How could you autotune/autoscale a standard sawtooth core VCO?  I suppose

If you're talking about digitally controlled VCO, it's fairly simple.
Typically the error is fairly smooth, so it is enough to measure the 
required CV at say, octave, intervals, store those to table and then 
interpolate the table to find the real CV output corresponding to virtual 
CV.

You can improve it by measuring the table on say startup, then removing 
any constant offset and gain. Now you can retune on the fly by measuring 
only three notes and then calculating the offset & gain adjustment from 
those. The key is that any nonlinear warping is probably not very 
temperature dependent so it can be assumed more or less constant.

Antti

"No boom today. Boom tomorrow. There's always a boom tomorrow"
   -- Lt. Cmdr. Ivanova