MOTM

'Evening all... having satisfied myself that my MOTM-120 is indeed in proper
working order (a good gain boost does help a lot, as well as judicious
selection of signals), I've started going over the MOTM-410 construction.
My question relates to R68, the resistor which is put in place when the
modular is to be used with MOTM-300 oscilators.  At some point in the
not-too-distant future, I'd like to use MOTM oscillators.  At the same time,
I don't want to leave out the option of using the filter on other signal
sources.  For the moment, I won't be soldering in the resistor.  

Is the resistor simply to be used on 10V peak-to-peak signals?  And if so,
will the planned pre-amp module bring signals up to that strength, requiring
the resistor at all times?  Or is there something else about the MOTM
oscillator (I can't imagine what exactly, amperage?) that makes it
necessary?

Thanks!!

--PBr

The pre-amp will boost to VCO levels. So leave it out now, and install when
VCOs arrive.

All this resistor does is keep the filters from clipping at 10V pk-pk. The
outputs from most
gear is 2V pk-pk max, more like 1V pk-pk.

The filter *still works* with the resistor in.

Paul S.

----- Original Message -----
From: Brousseau, Paul E (Paul) <PaulBr@...>
To: <motm@onelist.com>
Sent: Wednesday, January 05, 2000 7:49 PM
Subject: [motm] MOTM-410 question...


> 'Evening all... having satisfied myself that my MOTM-120 is indeed in
proper
> working order (a good gain boost does help a lot, as well as judicious
> selection of signals), I've started going over the MOTM-410 construction.
> My question relates to R68, the resistor which is put in place when the
> modular is to be used with MOTM-300 oscilators.  At some point in the
> not-too-distant future, I'd like to use MOTM oscillators.  At the same
time,
> I don't want to leave out the option of using the filter on other signal
> sources.  For the moment, I won't be soldering in the resistor.
>
> Is the resistor simply to be used on 10V peak-to-peak signals?  And if so,
> will the planned pre-amp module bring signals up to that strength,
requiring

> the resistor at all times?  Or is there something else about the MOTM
> oscillator (I can't imagine what exactly, amperage?) that makes it
> necessary?
>
> Thanks!!
>
> --PBr
>
>
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In a message dated 1/5/2000 6:53:52 PM, synth1@... writes:

>The pre-amp will boost to VCO levels. So leave it out now, and install
>when
>VCOs arrive.

As much as I hate to disagree with Paul (all of it on this list 
unfortunately), my suggestion would be to install the resistor now, AND tack 
solder a wire jumper across the top of it (a resistor lead for example). When 
you get more modular stuff, it will be very easy to remove the resistor 
clipping without taking the bracing plate (which covers the solder side of 
the PCB) off of the PCB which will require removing the front panel. This 
will save you a great deal of time when you make the modification.

JB

I installed R68 when I assembled the MOTM-410 and I've had no problem using
the -410 with either of my polysynths (Prophet 600, CZ-101), which I doubt
are anywhere near 10V outputs, even with the volume cranked.  So for a
third opinion, I'd recommend installing the resistor when you build the kit
and not worry about it.  I haven't tried running a low-level (guitar,
microphone, transducer pickup) signal through the -410 yet (so if you're
planning on *that*, you might want to ignore what I just said), but my
Morley wah (old chrome "Power Wah Boost") has a built-in preamp (the
"Boost") that ought to do the trick when the time comes.  I'd recommend
picking up the MOTM oscillator soon anyway, as the 300->120->410
combination sounds *huge*.

Also, potential 300/320 builders should know that the latest Radio Shack
circular lists their heat sink grease as on sale for $1.99 a tube (and
after having already built two, it looks like I'd have to build a wall of
oscillators to use up a single tube of the stuff).

	-Doug
	 ceres@...

At 05:49 PM 01/05/2000 -0800, "Brousseau, Paul E (Paul)"
<PaulBr@...> wrote:

>Is the resistor simply to be used on 10V peak-to-peak signals?  And if so,
>will the planned pre-amp module bring signals up to that strength, requiring
>the resistor at all times?  Or is there something else about the MOTM
>oscillator (I can't imagine what exactly, amperage?) that makes it
>necessary?

My suggestion is to bring a switch to the front panel.  Then you have the
best of both worlds.  I though a lot about doing this myself.

--Shemp

> 'Evening all... having satisfied myself that my MOTM-120 is
> indeed in proper
> working order (a good gain boost does help a lot, as well as judicious
> selection of signals), I've started going over the MOTM-410 construction.
> My question relates to R68, the resistor which is put in place when the
> modular is to be used with MOTM-300 oscilators.  At some point in the
> not-too-distant future, I'd like to use MOTM oscillators.  At the
> same time,
> I don't want to leave out the option of using the filter on other signal
> sources.  For the moment, I won't be soldering in the resistor.
>
> Is the resistor simply to be used on 10V peak-to-peak signals?  And if so,
> will the planned pre-amp module bring signals up to that
> strength, requiring
> the resistor at all times?  Or is there something else about the MOTM
> oscillator (I can't imagine what exactly, amperage?) that makes it
> necessary?
>
> Thanks!!
>
> --PBr