--- In tr-707@yahoogroups.com , "kingconga42" <kingconga8@a...> wrote:

> Slight tangent- would it be possible to bypass the sound rom (or the
> DAC, i guess) for certain sounds, and replace that audio with an
> oscilator that then passes thru the envelopes

Not really a tangent, this is something I thought of as well. Sure, one could fit an oscillator
in a 707 without too much trouble. It might not be as simple as ordinary envelopes go.
Usually you have a signal (like 707 sample, oscillator, etc) and play it through a VCA; the
VCA is opened and closed by an envelope signal from an ADSR, EG, etc. The 707
envelopes don't work like that, except for the crash and ride cymbals. The other voices in
the 707 come out of a DAC which uses the envelope signals to change the DAC reference.

What one can more easily do is make an oscillator with a small transistor VCA, then make
a simple two-part envelope which is fired from the 707 gate pins. It might take some
fiddling to get the new osc to be about the same volume level as the sampled sounds.

Just a single bleeping oscillator gets boring as a drum sound, IMO. So I prefer simple VCOs
with separate pitch and amplitude envelopes. I was thinking seriously about making all
analog voices for a 707, but unless one is a circuit layout guru using surface-mount parts,
I can't see how to fit such a big project in there - or all of the new controls I'd want. One
project I am going to get going one I can afford another drum machine is to bolt the top
panel of a 707 onto a new bottom case which is a bit wider and deeper. Then I can fit
more mods and decent analog circuitry, like 808, 909, and other style voices. Since the
original voicing board still needs to be there, voices can be chosen by switches or just run
through extra outputs to a mixer.



Would the sound be

> gated as well As far as sound samples go, i just ordered an eprom
> programmer- i know very little about this stuff, i hope to learn more...
>
> -justin
> = burnkit2600.com =