PLAN B analog blog

I have a Model 15 which is picking up some interference/unwanted
modulation from two of its neighboring modules: a Model 28 and a Dalek
Modulator.  When the Model 28 is running, I can hear its pulses coming
through the Model 15 output.  The Dalek is causing the same problem,
mainly when one or both oscillators are in the 'low' range.  All three
modules are in an older Doepfer enclosure with an NT12 PSU.  Any
suggestions?

the best solution is powering the M15 if you can from an entirely
different rack.  If it's the only one you have, then follow the center
most connection suggestion made previously.

There's something that all of the current manufacturers of Eurorack
Racks (actually, not sure about Cwejman) have in common:  absolutely
no power management.  The manner in which they dasychain the power is
about the worst possible way it could be done, for all the reasons
you're experiencing.  Modules which by nature (most LFOs, not just
Livewire) and anything with a microp in it tend to make noise which is
transferred through the ground line.  If there are audio modules
powered on the same row, or at worst case from the same supply, all
the noise (usually associated wth zero transitions, when something
crosses or hits zero volts) picks up that noise.  What is required are
separate lines directly from ground to all of the connectors on the
row of the bussboard.  A failsafe solution wold be to power contrl
modules and audio modules from separate supplies.  This wold fix the
proble entirely.

If you scan through the letters on this blog you'll notice this is
exactly what we're planning with the Plan B case. There will be one
bussbiard to each row, but all grounds will be going directly to the
power supply return and every other connector will be physically 
offset form one another, one labeled AUDIO and the other CONTROL.  We
may actually power each of these from a different set of regulators.

~m

Thanks Peter (and Tony).  I do have an empty rack at the moment, but
obviously that will get filled eventually, so I was looking for a more
permanent solution.  The M15 and Dalek are currently in one row, while
the M28 is in the other row.  The M15, however, is currently the last
module on the buss board.  I'll try moving it to the center and see if
that helps.  Thanks again for the suggestions!

--- In PLAN_B_analog_blog@yahoogroups.com, "(i think you can figure
that out)" <peter@...> wrote:

>
> the best solution is powering the M15 if you can from an entirely
> different rack.  If it's the only one you have, then follow the center
> most connection suggestion made previously.
> 
> There's something that all of the current manufacturers of Eurorack
> Racks (actually, not sure about Cwejman) have in common:  absolutely
> no power management.  The manner in which they dasychain the power is
> about the worst possible way it could be done, for all the reasons
> you're experiencing.  Modules which by nature (most LFOs, not just
> Livewire) and anything with a microp in it tend to make noise which is
> transferred through the ground line.  If there are audio modules
> powered on the same row, or at worst case from the same supply, all
> the noise (usually associated wth zero transitions, when something
> crosses or hits zero volts) picks up that noise.  What is required are
> separate lines directly from ground to all of the connectors on the
> row of the bussboard.  A failsafe solution wold be to power contrl
> modules and audio modules from separate supplies.  This wold fix the
> proble entirely.
> 
> If you scan through the letters on this blog you'll notice this is
> exactly what we're planning with the Plan B case. There will be one
> bussbiard to each row, but all grounds will be going directly to the
> power supply return and every other connector will be physically 
> offset form one another, one labeled AUDIO and the other CONTROL.  We
> may actually power each of these from a different set of regulators.
> 
> ~m
>

For the record, different rows is the hopeful solution.  Different
racks (meaning different PSUs) is the best fix.

I had the same problem in my system.  Some modules created noise (LFOs
the worst offenders), some were suspect for interference from that: 
Model 15's and the Frequensteiner which is highly suspect due to it's open amp design. I made it go away by eventually running control modules and audio modules from different PSUs.  That's what fixed it.

hope this helps,

- P




--- In PLAN_B_analog_blog@yahoogroups.com, "deastman2" <deastman2@...>
wrote:

>
> Thanks Peter (and Tony).  I do have an empty rack at the moment, but
> obviously that will get filled eventually, so I was looking for a more
> permanent solution.  The M15 and Dalek are currently in one row, while
> the M28 is in the other row.  The M15, however, is currently the last
> module on the buss board.  I'll try moving it to the center and see if
> that helps.  Thanks again for the suggestions!
> 
> --- In PLAN_B_analog_blog@yahoogroups.com, "(i think you can figure
> that out)" <peter@> wrote:
> >
> > the best solution is powering the M15 if you can from an entirely
> > different rack.  If it's the only one you have, then follow the center
> > most connection suggestion made previously.
> > 
> > There's something that all of the current manufacturers of Eurorack
> > Racks (actually, not sure about Cwejman) have in common:  absolutely
> > no power management.  The manner in which they dasychain the power is
> > about the worst possible way it could be done, for all the reasons
> > you're experiencing.  Modules which by nature (most LFOs, not just
> > Livewire) and anything with a microp in it tend to make noise which is
> > transferred through the ground line.  If there are audio modules
> > powered on the same row, or at worst case from the same supply, all
> > the noise (usually associated wth zero transitions, when something
> > crosses or hits zero volts) picks up that noise.  What is required are
> > separate lines directly from ground to all of the connectors on the
> > row of the bussboard.  A failsafe solution wold be to power contrl
> > modules and audio modules from separate supplies.  This wold fix the
> > proble entirely.
> > 
> > If you scan through the letters on this blog you'll notice this is
> > exactly what we're planning with the Plan B case. There will be one
> > bussbiard to each row, but all grounds will be going directly to the
> > power supply return and every other connector will be physically 
> > offset form one another, one labeled AUDIO and the other CONTROL.  We
> > may actually power each of these from a different set of regulators.
> > 
> > ~m
> >
>

On Feb 4, 2008, at 4:11 PM, Romeo Fahl wrote:

> Sounds like Buchla's approach... at least with the 200 series. It  
> amazes me that as expensive as some other systems are, how little  
> thought was put into power distribution.
>
On the SMS system we went completely overboard, by distributing a  
roughly regulated +/- 18 V. and requiring each module to have its own  
regulators. There was also a clean and a dirty ground distributed.

http://www.xfade.com/gear/Salamander/

-C

Chris said:

On the SMS system we went completely overboard, by distributing a  
> roughly regulated +/- 18 V. and requiring each module to have its own  
> regulators. There was also a clean and a dirty ground distributed.
> 

Ouch.  Effective, but yes, probably overkill.

What I am thinking is:

1) Putting two sets of regulators on each bussboard, with one for
control modules and the other for audio modules. It would be up to the
user to adhere to this, but in the name of quiet operation it would be
in his/her best interests to do so.

2) The important part is that the six ground pins of each power
connector on the bussboard lead directly - on it's own trace - to it's
associated regulator's return (ground). 

3) The inputs to each bussboard would come from a common power module
- a 1 rack high rack mount job which would house the three tap
transformer, in which each of the three was terminated by the Bridge
Rectifier which would be available at three output connectors which
would lead to up to three bussboards. (three racks).  The front face
of the power module wold have mult on it, or something alng those lines.

I think this would be sufficient. 

- P

 



--- In PLAN_B_analog_blog@yahoogroups.com, Chris Muir <cbm@...> wrote:

>
> 
> On Feb 4, 2008, at 4:11 PM, Romeo Fahl wrote:
> 
> > Sounds like Buchla's approach... at least with the 200 series. It  
> > amazes me that as expensive as some other systems are, how little  
> > thought was put into power distribution.
> >
> On the SMS system we went completely overboard, by distributing a  
> roughly regulated +/- 18 V. and requiring each module to have its own  
> regulators. There was also a clean and a dirty ground distributed.
> 
> http://www.xfade.com/gear/Salamander/
> 
> -C
>