MOTM

I was meandering through some of your sites, when I came across a
mention - I think it was on Richard Brewster's site - that he'd put
his Oscillators on one power supply to isolate them from some kind of
interference from other modules.  So I became concerned about how Will
and I have been planning our power distibution.  Here's how we've been
lanning it:

On a MOTM 900 - 

(1) MOTM 101  Noise/S&H
(1) MOTM 120  Sub Oct Multiplexer
(1) MOTM 190  VCR
(3) MOTM 300  Ultra VCO
(2) MOTM 310  Micro VCO
(1) MOTM 410  Triple Resonant Filter
(1) MOTM 420  VCF
(1) MOTM 440  Discreet OTA Lowpass Filter
(1) MOTM 480  CS REsonant Filter
(1) MOTM 495  VCF
(1) MOTM 490  Micro VCF
(1) MOTM 320  VC LFO
(1) MOTM 380  Quad LFO
(2) MOTM 390  Micro LFO

On a MOTM 950 -

(5) MOTM 800  EG Outfitted with Scott Juskiw's 800DBs and two LEDs each
(1) MTOM 510  Wave Warper (needs the 6pin connector)
(1) MOTM 700  Dual VC Router
(1) MOTM 800  Lag Processor
(1) MOTM 830  Dual Mode Mixer
(1) MOTM 650  Midi-DC Converter (needs the 6pin connector)
(1) MOTM 850  Pedal Interface


Now, according to my reconing - we should be within each of the power
supplies' load tolerance.  On the Synth tech site, Paul says the 900
can handle up to 20 Modules (I've specified 18).  Now Paul also says
that the 950 has 6 MTA-156-6pin connectors and 3 standard MTA-156-4
pin connectors.   I figured by using a MOTM-960 Adapter Board we could
get the remaining modules attached to the 950.

There's no doubt that we're pushing the limit... and if we want to add
more modules - well - we'll need more power.

So here's our question:

GIVEN THAT 
- although using the two power supplies may be OK during construction
and initial testing of our synth

AND GIVEN THAT
- we think we ultimately need to add an additional 900 power supply

HOW do you recommend 
- we connect the above modules to the (2) 900s and (1) 950 to minimize
the interference mentioned by Richard Brewster?

Thanks much.

Bill and Will

I don't remember what I may have said about interference between 
modules.  I did try to follow some advice from Ken Stone and separate 
out digital type modules -- especially modules like the CGS Burst 
Generator -- onto a separate power supply.  These are collected in a 
cabinet oriented toward digital, having sample and holds, noise, pulse 
dividers, and so on.   In actual practice I have not encountered any 
"interference" type problems; I was just being proactive.

Since your list is all MOTM, and since these are just about the lowest 
noise modules around, I don't think you have much to worry about.  But 
make sure you can swap your modules around.  Then, if you ever do detect 
interference (noticeable, audible interference that you can relate to 
some event, such as a sample and hold being triggered), you will be able 
to move modules to share different power supplies, which could address 
the issue.

Richard Brewster
http://www.pugix.com

wjhall11 wrote:

> There's no doubt that we're pushing the limit... and if we want to add
> more modules - well - we'll need more power.
>
> So here's our question:
>
> GIVEN THAT 
> - although using the two power supplies may be OK during construction
> and initial testing of our synth
>
> AND GIVEN THAT
> - we think we ultimately need to add an additional 900 power supply
>
> HOW do you recommend 
> - we connect the above modules to the (2) 900s and (1) 950 to minimize
> the interference mentioned by Richard Brewster?
>
> Thanks much.
>
> Bill and Will
>
>
>

Richard - ah - thanks so much for clarifying - my use of
"interference" was imprecise to be sure - I was using it in a very
broad sense.

We're new at this and we really appreciate your advise.

OK - well - we are also trying to be proactive - and because of that,
we probably will add another 900 eventually.  That means we need to
anticipate space for it, of course.

We're also considering moving to a somewhat narrower 39 inch wide
three-tier layout for our synth as opposed to our original 48 inch
wide two tier design.  This will leave more space for expansion, make
patching a little easier, and make the power supply seperation of
digital vs other modules a little easier to do in the context of our
layout - just in case it becomes an issue.

Thanks so much again.

Bill and Will



--- In motm@yahoogroups.com, Richard Brewster <pugix@...> wrote:
>
> I don't remember what I may have said about interference between 
> modules.  I did try to follow some advice from Ken Stone and separate 
> out digital type modules -- especially modules like the CGS Burst 
> Generator -- onto a separate power supply.  These are collected in a 
> cabinet oriented toward digital, having sample and holds, noise, pulse 
> dividers, and so on.   In actual practice I have not encountered any 
> "interference" type problems; I was just being proactive.
> 
> Since your list is all MOTM, and since these are just about the lowest 
> noise modules around, I don't think you have much to worry about.  But 
> make sure you can swap your modules around.  Then, if you ever do
detect 
> interference (noticeable, audible interference that you can relate to 
> some event, such as a sample and hold being triggered), you will be
able 

> to move modules to share different power supplies, which could address 
> the issue.
> 
> Richard Brewster
> http://www.pugix.com
> 
> wjhall11 wrote:
> > There's no doubt that we're pushing the limit... and if we want to add
> > more modules - well - we'll need more power.
> >
> > So here's our question:
> >
> > GIVEN THAT 
> > - although using the two power supplies may be OK during construction
> > and initial testing of our synth
> >
> > AND GIVEN THAT
> > - we think we ultimately need to add an additional 900 power supply
> >
> > HOW do you recommend 
> > - we connect the above modules to the (2) 900s and (1) 950 to minimize
> > the interference mentioned by Richard Brewster?
> >
> > Thanks much.
> >
> > Bill and Will
> >
> >
> >
>

Please read my pages on power supply distribution. http://www.hotrodmotm.com/distribute.htm Moe ... -- Dave Bradley

Bill, FWIW, I have had no issues with PS noise or stability no matter how I distribute my modules across the two supplies in my system. Actually there are 3