[sdiy] Sample&Hold thoughts

[Dave Krooshof]

>What I'm wondering now is, is it possible to clock sample n' holds at
>extreme clock speeds, say around 11khz-22khz, or even higher.
>I guess you know where I'm going with this.
Depends a bit how spikey the triggers can be for yr device.
As the realtionship between audio an the trigger might be noise, that is,
Your trigger is irregular, you end up with noise.
If your trigger is regular (as in, relates to a clock) you have something
like an analogue to analogue convertor:
Going from analogue to digital is done, in a few words, like this: you
sample the voltage at each clockpulse, and put that into a number. In your
case you do not go into the numbering part, but you go straight 'back' into
voltages.

If you use the sampled voltages for FM, you get mutulated sounds.
You'll be generating a noisy sound with an awkward relation to yr audio.
BEA5 (a huge analogue studio in The Hague) could do this a bit.
I had a bassy note that got noisy on audio input.

>the only
>difference would be that you could change the fidelity in real time
>over an extremely wide range by changing the clock rate, right?
Depends on what you do with the voltage out of the T-SAH.
If you listen to that directly, you're correct.

>I'm just drooling over the thought now of "Sample rate modulation",
>say if you modulated the clock speed from an external LFO or
>something.
Get a toy that samples sounds (costs 5$ or so)
They usually sample at 8KHz or so.
It's easy to tweak their clock by putting you're fingers on the board at
places.
Up is easier then down in this situation. Pity you'd also change the
playback pitch that way, but you can know if this hifinesscontrol is what
you want.
Or you could use your computer to save audiofiles in different fileformats.
Keep the bits at 16 though, in your plan you have endless bytesizes
(because analoge).

HTH

Dave

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Dave Krooshof http://www.xs4all.nl/~krooshof
geluidstechnicus @ http://www.ahk.nl/the/theatertechniek_ov.html
webmaster: http://www.popronde.nl
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