SV: a 2600 2600

Theo t.hogers at home.nl
Fri Mar 24 11:18:41 CET 2000


----- Original Message -----
From: Ben Stuyts <ben at stuyts.nl>
To: Theo <t.hogers at home.nl>
Cc: <synth-diy at node12b53.a2000.nl>
Sent: Friday, March 24, 2000 9:42 AM
Subject: Re: SV: a 2600 2600


> That brings back old memories.... You mean the ACN SoundTrack cartridge? I
> made that thing somewhere around 1987. That is really nice to hear
somebody's
> still using them.
>
Nice to here from the one who made this F er.. Fantastic thing.
No really it has been a kind of love hate relationship for me.
Actually it stoped working 2 months ago, need to revieve it, it's my mean
sampler.
(no 8 bit sounds wonder full)
>
> It was made to be compatible with another sampler cartridge at that
time...
> Uhm, forgot the name. Some English product I think. That was important,
because
> a lot of software would work with it that way. That's why we choose the
weird
> 'write by reading' trick. If I remember correctly, by setting up your
registers
> careful you could reach sampling/playback speeds of up to 55 kHz that way.
>
The ST is faster than that, it does 100KHz using the sound merlin FINT
routine,
no more room for annything else in that case (;-)
You say 'choose' the write by reading trick, is there an other way to write
to the rom port?
>
> > The AA filter is fixed at 10KHz with a 6dB slope.
>
> It sounded a bit harsh, didn't it? B-) Wasn't it 12 dB by the way? Can't
> remember exactly. I do remember it had to be cheap. The English cartridge
had a
> lower frequency cut-off, but sounded too mellow at higher sampling rates.
>
Yhea was 12dB, brings me to the mods..
> Please tell me about your mods?
>
The first one was a quicky, it needed a gain pot.

Next the damed thing was mono, (not your fault, ACN was in thrue hyper
comercial
ACN style not clear about the fact in the add. They even mentioned sterio
connectors.)
So a pseudo sterio circuit was added.
(gona put a version of the pseudo sterio on my site some day,
works great in a DX synth should do well in other mono synths too.)

The last mod went to some revisions, the filter was replaced by one that
follows the
sample ferquentie.
There are two versions. One used four fixed filters, sample freq. was used
to switch
bedween them. The second one uses a VCF and a freq to CV aproach.

Cheers Theo.






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