This mod has been brought up once or twice before here. I vaguely
remember looking into it briefly, and that it was not entirely
straightforward. You'd have to replace the simple pot / voltage
divider on the comparator hysteresis (positive feedback) loop with
some sort of opamp summing node. So at a minimum, find panel space
for 2 more jacks, and add an extra pcb with a couple of dual opamps
and some resistors. So circuit wise it's not bad, but physically it's
a little work.
BTW, the Serge is just a digital comparator (ignoring the staircase
part). The 700 is a bi-directional audio router that can be patched
with dc voltages to give you a digital comparator, and so is
considerably more flexible in that sense.
Moe
--- In motm@y..., norman fay <NFAY@F...> wrote:
> This is a module I haven't got yet, though I do mean to get one, as
I
> can imagine several uses for it. At the same time, I've been
looking at
> the serge "com" (dual comparator) and comparing them feature-wise.
> Though both modules are based around a voltage-controlled switching
> function, both modules produce different results. The MOTM
switcher,
> I'm sure you all know about. The serge comparator, OTOH, has two
inputs
> marked + and -, a threshold knob and a single output per channel.
what
> they do is this: one runs a different voltage/signal into each
channel.
> If the + signal is greater than the - signal, the output goes high
(+5v)
> if not, it goes low (0v) Using the threshold control, one can
either
> generate square waves/pulses from a single input, or raise or lower
the
> + signal (I think....). I've been racking my brains trying to come
up
> with a way for the motm700 to do this. The voltage bit is easy -
set
> the mode to voltage, and feed it with +5v into one input and 0v
into the
> other (you could use l. hendry's octave switcher to generate the
5v)
> however, the dual cv inputs are a problem....the only way to do it
would
> be to add another cv input to each half of the module, which would
> interact with the "switch" knob. In this case then, if the
> signal/voltage at "cv in" is greater than that at our new input, the
> module would switch one way, if it were lower, it would switch the
other
> way. In this case, the "switch" knob could add or subtract from the
> voltage present at the new input, thus acting as a threshold
control.
> Now, I'm absolutely ∗sure∗ that there are folks on this list who
could
> perform this mod!
> Now, the question you'll be asking is this: why? Well, here's a
few
> possibilities:
>
> 1/ from the MOTM700 page at www.synthtech.com:
> "audio demo - chopped up audio switching between 2 waveforms with
the cv
> as a 250 hz triangle. you can hear the timbre shift as we manually
move
> the SWITCH control"
> with this extra cv in, you could control this timbre shift with an
> envelope or an lfo.
>
> 2/ with a sequencer - clock the sequencer with a narrow pulse wave
lfo
> signal, also run pulse wave into MOTM lag processor (fastest attack,
> slower decay) run lag proc out into CV in of MOTM700, run cv source
(eg
> lfo or second row of sequencer knobs) into new switch CV input. 5v
into
> one i/o socket, 0v into other - result = VC gate time!
>
> 3/ vco triangle wave into cv input, lfo or adsr into new input, +5v
into
> one i/o socket, 0v or -5v into other - result = second (or third,
using
> both sections of motm700) pwm wave from single VCO!
>
> pretty cool, eh? Any thoughts? Anyone fancy getting to work on
this?
>
> please!
>
> best wishes
> --
> norman fay