[sdiy] TR-7x7? (was Re: Proms)

[Drew Smith (mux)]

On Thu, 2002-09-26 at 07:01, Dan Gendreau wrote:

> There is a simple R/C analog envelope generator for each drum tone except
> for CC/RC. CC/RC are output directly from a 6bit DAC with no envelope, which
> explains why the 707 CC/RC sound kinda cheap. All other drum sounds are
> multiplexed through an 8bit DAC.

	Holas,

	This is *great* stuff!  I haven't used my TR-707 in months,
specifically because of the difficulty in using the sounds in a mix...
I'm a total novice when it comes to digital circuitry tho; what is the
significance of the 8bit or 6bit DAC - can they be easily converted to a
higher-quality DAC, if the pinouts are similar, or is the circuit
dependant on the output of that particular DAC?  I know of the
modification to add pot-control of the decay on the open/closed hats,
but are you saying that *all* the sounds ('cept the CC/RC) use
individual VCA's?

> I have both the 707 and 727, and I must agree with Drew... I love the
> TR707/727 user interface, much more than the 909, but I hate the sounds. If
> I had the time to break out the individual drum triggers, it would make a
> fantastic front end to any analog drum tone project.

	Heheheh - I explored this a bit, but didn't want to destroy the machine
through experimentation!  I ended up adding a Paia Midi2cv8 kit to my
Simmons SDS-800 drum brain, which basically put the 707 on the shelf.
:(  In an ideal modification, the top of the casing would be replaced
with a cast-aluminum casing, like the ones they're making for the
TB-303, and each of the outputs would have a toggle-switch between
audio-out and trigger-out (maybe a 3-way toggle, to allow the jack to
send a trigger *and* reroute the audio to the mix-out?)... also..:

> Ideally, It would be cool to substitute in a larger rom with many banks to
> chose from. Better yet, use a uC to download sounds to SRAMs via Sysex! But
> alas, I havent had the free time to tackle any of that yet. :)

	This is *really* an exciting idea!!!  Is something like this even
possible?!?  If this could be created as a kit, I'm certain many folks
would be interested, regardless of price!!  I'm afraid my level of skill
doesn't really offer much towards a project of this complexity, but I'd
love to be a part of it...

	Oh, hey - speaking of trigger-outs, the Midi2cv8 gave me 8 triggers.  I
used four of them for the four voices on my SDS-800, and brought the
other four to 1/4" jacks on the back (pics at
http://mux.ca/gear.html)... I've been tossing around the idea of
modifying a few of those cheap strobe lights they sell at the "raver
store" in the malls, adding a 1/4" jack for a trigger pulse, so that I
could control a couple of strobe lights over MIDI... anyone done this?

	Cheers,
	- Drew.

-- 
Drew Smith (mux) <drew at riotnrrd.com>
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