[sdiy] SAW core VCO flyback time

[Donald Tillman]

> On Aug 30, 2016, at 10:40 AM, mskala at ansuz.sooke.bc.ca wrote:
> 
> On Tue, 30 Aug 2016, Richie Burnett wrote:
>> BTW, I think it's fascinating how the analogue designers strive to achieve
>> perfection in the form of "instantaneous" sawtooth resets, low-distortion
>> sinewaves, and symmetrical triangle waveforms without the little nipple at the
> 
> I was holding off on saying it, but if you're serious about analog design,
> do you even *want* a super-fast reset?

The high C on a traditional piano is 4186 Hz.

A 2uSec reset delay would pull that down to 4152 Hz, for a 35 Hz beat. 

A 7uSec reset delay would pull it down to 4066 Hz, halfway down to the next lowest note.  That would be unplayable.

The effect is worse when you're playing along with stringed instruments with stretched turning.

Besides the capacitor discharge, the delay would include the comparator sensing the limits.

So the concern about reset time is not for the timbre.  I mean, hell, sawtooth waves are so boring already that any timbral variation would be welcome.  Amiright?

The ARP/Rhodes Chroma VCO had a unique charge pump VCO core that had a long reset time, but the reset didn't introduce a tuning delay in the cycle.

  -- Don

--
Don Tillman
Palo Alto, California
don at till.com
http://www.till.com