[sdiy] X8 squarewave multiplier.

[Jaco Sloof]

Hi Harry,

reply is inline.

--- harrybissell <harrybissell at prodigy.net> wrote:

> The important features of the sawtooth are
> 
> 1) No change in amplitude with frequency
> 

Yup, it would mean that when amplitudes don't have a "standard" loudness-curve,
using it to select waveform samples is going to be funny. Might be a feature :)

> 2) No change in DC offset with frequency
> 

Could be usefull. Imagine, coming in is a 0-10V (unipolar) sawtooth. Scale it
to be 0-5V and add 5 volts. It would uhm,
 "rectify the wavetable-waveform", because it only uses (in case of 8 bits)
sample 127-256. Good feature!

> 3) Sawtooth linearity
> 
Jitter is fine. It's like the alarmclocks that sync time through the 60 Hz
powerline. They might not be accurate on (very) short timescales (measure every
0.001 Second), but they are stable as heck on large ones. Also, when
translating this through to a 8x mult (or worse when using wavetables), it does
create jitter, but the overall frequency (and phase when looking at large
timescales,  such as 1 complete cycle of a waveform) tracks the input nicely.
(in my head anyway)

> 4) Fast reset time.
Yup, or it would pop out samples while going back to zero.
> 
> If any of these are not there, jitter or other
> distortion will result. Maybe it will be a problem,
> maybe a feature :^P
> 
Personally, I like the idea a lot! Its not high Fi or anything, but I like my
sounds grungey, bleepy, micromusic.com'ey.

> wouldn't you want ALL these in a good VCO...
> alas, there are a lot of BAD VCOs out there too...
> 
> The TB-303 sawtooth with the 'flat spot' at the
> top would be an awful choice.  The Yamaha clone
> VCO that Old Crow did would be a bad choice
> as well (because of the unusual reset waveform).
> 
> H^) harry
> 

Greets, Jaco Sloof

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