[sdiy] Thomas Henry SN-Voice Page is Up

[scottnoanh at peoplepc.com]

> Wow, that's great! I don't have a spare 76477, but there seem to be
> quite a few mods that could easily be incorporated into my Blacet
> Dark Star. Of course I'm most interested in add V/Oct to my DSC. Am I
> reading correctly that you tried using the DSC's PWM circuit and the
> V/Oct tuning was stable?
>
> Thanks,
> Chris

Well, when Thomas was designing the SN-Voice, he'd pretty much ruled out
putting PWM in because the original design had pin 16 tied to ground - that
pushed the high end to better than 15 kHz.  I, on the other hand, love the
sound of the PWM on the DSC2000.  I wired up the breadboard with John's
values and recorded a sample that I sent to Thomas and posted on this list
under the "Guess That Chip" thread.  Problem was, the DSC2000 is proprietary
to John, and Thomas doesn't have one, so it was a situation where I didn't
want to say "try these values", but rather it was "can you make it sound
like this?".

Anyway, IIRC it may have limited the top end a bit under than the original
DSC2000 (can't remember if that's the case), but the tracking would
certainly be no worse than what's in the sample (I really do suck at tuning
VCO's of any species).

Here's the link to the sample:

http://mypeoplepc.com/members/scottnoanh/sitebuildercontent/sitebuilderfiles
/whats_this.mp3

If you try it, you might also see if you can switch between LFO and PWM
controlled EG - I think it's just a matter of switching one signal in over
the other.  The Blacet values really gave it balls (a lot wider range of
sweep than the SN-Voice).  If you try it, you might check to see if the VCO
detunes from one setting to the other.  If it does, it may just be a few
cents and something you can live with.

Cheers,
Scott