MOTM

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

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

You can get them same effect by adding a control voltage to the waveform
you're using at the CV input of the 700. Imagine you have your switch
set to 
occur at the zero crossing of your waveform. As you add a positive voltage
you bias the waveform so that switching occurs more on the negative peaks,
as you subtract voltage, the waveform moves down and switching occurs on
the positive peaks. Sort of "If you can't raise the bridge, lower the river."
Larry first suggested this to me when I was wanting the same mod.

Tomy

norman fay 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
>

Norman,
This is some really great stuff.  You got me thinking WHY?  And then you
answered.  A very thoughtful mail no doubt.
The CV input of the 700 already feeds a comparator.  The + side fed by the
switch pot is already scaled for + / - 5 volts by the resistors at the ends
of the pot.  So, I cannot see any reason that you could not use a voltage
input here instead of the switch pot.  My lack of expertise leaves me with
some questions though.

Standard Stooge Disclaimer - I have not tried this.  Do not do this.  This
is for the purpose of discussion.

1 - would you need to buffer the input - I don't see why
2 - would you need a filter on the CV input like Paul has
     put on the actual CV input (R9 and C7).

But, in general, it seems like you should be able to interrupt the
connection between VR1 and the LM311 pin 2.  Put your CV input jack here and
set VR1 wiper to the switch on the new jack to that when nothing is plugged
into the new CV jack, VR1 functions as normal.

If you wanted to still have the biasing ability of VR1, it would seem to me
you would need to add a summing stage to add the voltages of the pot and
this new CV input prior to going to the comparator.  But, that seems
unnecessary and beyond what you were trying to accomplish.

Very interesting.  I like your thoughts on this.

Larry

P.S.  without modification, the 822 voltage switch will only output 3.917
volts max.

----- Original Message -----
From: norman fay <NFAY@...>
To: <motm@yahoogroups.com>
Sent: Friday, February 09, 2001 6:58 AM
Subject: [motm] suggested mod for motm700 (longish)


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

I just ordered this module , now what the hell are I going to do .  Any
of you 
readers for any amount of time knows that Norm Fay is not f to be
regarded in the least bit  lightly..  those of us who make serious noise
or serious money doing this must pause.   ..  C'mon guys I work for the
feds and have been detached hence no time.to volunteer.


Help

G Wong
 
"J. Larry Hendry" wrote:

> 
> Norman,
> This is some really great stuff.  You got me thinking WHY?  And then you
> answered.  A very thoughtful mail no doubt.
> The CV input of the 700 already feeds a comparator.  The + side fed by the
> switch pot is already scaled for + / - 5 volts by the resistors at the ends
> of the pot.  So, I cannot see any reason that you could not use a voltage
> input here instead of the switch pot.  My lack of expertise leaves me with
> some questions though.
> 
> Standard Stooge Disclaimer - I have not tried this.  Do not do this.  This
> is for the purpose of discussion.
> 
> 1 - would you need to buffer the input - I don't see why
> 2 - would you need a filter on the CV input like Paul has
>      put on the actual CV input (R9 and C7).
> 
> But, in general, it seems like you should be able to interrupt the
> connection between VR1 and the LM311 pin 2.  Put your CV input jack here and
> set VR1 wiper to the switch on the new jack to that when nothing is plugged
> into the new CV jack, VR1 functions as normal.
> 
> If you wanted to still have the biasing ability of VR1, it would seem to me
> you would need to add a summing stage to add the voltages of the pot and
> this new CV input prior to going to the comparator.  But, that seems
> unnecessary and beyond what you were trying to accomplish.
> 
> Very interesting.  I like your thoughts on this.
> 
> Larry
> 
> P.S.  without modification, the 822 voltage switch will only output 3.917
> volts max.
> 
> ----- Original Message -----
> From: norman fay <NFAY@...>
> To: <motm@yahoogroups.com>
> Sent: Friday, February 09, 2001 6:58 AM
> Subject: [motm] suggested mod for motm700 (longish)
> 
> 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
>

In message <9618pa+d651@...>, mate_stubb@... writes
>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.
>
I'm not up to the circuit bit, but the board (if its only a couple of
dual opamps & some resistors, this should be stripboardable, yes?) and
the 2 extra sockets shouldn't be an issue for me - BTW, I figure a good
place for the sockets would be if you were to draw an imaginary line up
from the third column of sockets on the existing module, and intersect
it with a line drawn from the two rows of LEDs.

>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.
>
Aye...I'm a greedy sort, though.  <wails> I WANT IT ALL!! </wails>
I think I will move the MOTM700 up my schedule of modules to buy,
though.
best etc 
-- 
norman fay

--- In motm@y..., norman fay <NFAY@F...> wrote:
> BTW, I figure a good place for the sockets would be if you were to
> draw an imaginary line up from the third column of sockets on the 
> existing module, and intersect it with a line drawn from the two 
> rows of LEDs.

Glancing at mine, I don't think you'll totally clear the pcb at that 
location - there are tall electrolytic caps that infringe into at 
least one of those locations.

Moe

Actually, I think the spaces as I understand what Norman describes look
pretty clear in the back.  I would have chosen the spots directly under the
pots (in line), but those just won't work at all.  But, if they were put
just outside the box to the right of the LEDs, I think they would clear OK.
They you could add a white line down and over from the bottom of the pot
scale.
Just my $.02
Larry

----- Original Message -----
From: <mate_stubb@...>
To: <motm@yahoogroups.com>
Sent: Saturday, February 10, 2001 12:35 PM
Subject: [motm] Re: suggested mod for motm700 (longish)


--- In motm@y..., norman fay <NFAY@F...> wrote:
> BTW, I figure a good place for the sockets would be if you were to
> draw an imaginary line up from the third column of sockets on the
> existing module, and intersect it with a line drawn from the two
> rows of LEDs.

Glancing at mine, I don't think you'll totally clear the pcb at that
location - there are tall electrolytic caps that infringe into at
least one of those locations.

Moe