my first message came back to me after all. here it
is:

thanks for starting this group, the 707 is the center
of my
operation. i will post info and instructions about
mods as i do them.

as for the mc64, cool idea. i can't help you out
though, in fact i
tore the whole slot out of mine to make room for some
big switches to
switch between the sounds of the 707 and 727. i'm
planning to use
switches from those big printer switcher boxes that
switch between
serial ports that have 25 pins. the voice roms for the
707/27 have 28
pins. my plan is to put sockets where the voice roms
are, then put
the voice roms on a separate circuit board (with
sockets), hook up +
and gnd and pin 22 (called chip select) to the
positions on the
original board, then hook the remaining 25 pins to the
25 wires
coming from one of the positions of the switch, and
the two voice
roms on the new board to the other 2 positions. i'm
thinking maybe
the easiest way to do the hookup is to find the right
size ribbon to
go between the sockets and the new board with the roms
and switches.
any opinions i'll definitely post my findings.

other ideas:
1. since i have the decay mods and vca inputs, i'm
thinking of also
adding some kind of cv input or internal oscillator
for amplitude
modulation of the cymbal/hh/external sounds.

2. 808 oscillators. the 808 hihat, cymbal, and cowbell
sounds are
generated by a hex schmitt trigger chip that is wired
as 6 squarewave
oscillators, which are mixed with resistors and then
filtered. my
idea is to at least build the oscillator section (chip
and a few
resistors and capacitors) and see how it sounds, then
maybe some
simple bandpass filters with frequency knobs. then
i'll plug them
into my vca inputs so i've got 808hh/707hh,
808cy/707ride, and
808cowbell/707crash! the cool thing too is that you
can tune the
pitch of the oscillators by varying the power with a
pot (5v max!). i
don't know if this has any relevance for anyone
because you need the
decay/vca mod for this to be useful, but if you
haven't done it i
highly recommend it. i'll upload plutonique9's
instructions from
Analogue Heaven, as well as the 808 schematics. the
modern day
equivalent of the chip in the 808 is call 74hc14 hex
schmitt trigger.

3. multiple trigger outs. this one i haven't quite
figured out. i
currently use the rimshot trigger to sequence an
analog bass drum. i
have a few other devices and 4 or 5 more trigger outs
would be
extremely useful! i have found the internal triggers
in the 707, but
they seem really low amplitude and maybe even negative
going. i
imagine this sort of thing can be done with a
comparator otherwise,
i'm going to try with a 555 configured as a fast
one-shot. again,
i'll post info when i try it out.

greg


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