In my case, I can't really contact Doepfer direct as I'm using a mix
of A Sys, Doepfer and homemade modules with a 6U A Sys case and a 6U
homemade case Power-one PSU). That said, the trouble started before
I added any of the homemade stuff and I added the a-146 LFO to the A
Sys case. That was the clincher. I agree that the LED may not be
causing the problems, but in my case, the modulation is clearly co-
incident with the the LEDs - speed up the LFO/ADSR or whatever, and
the modulation speeds up, too. I'm also well within my Ampage limit
(by about 3 Amps)
While I may be wrong, I believe that my cases are correctly
grounded. I've tested the voltages of the PSUs and they check out.

I was particularly interested in a thread when I first raised this
problem here which Julian and others helped with. Then, it was
mentioned that adding large capacitors across the power rails might
help. My questions are:

what sort of value is recommended
Does a cap have to be added at the end of each distribution board, or
is one pair in a system enough
What type of cap is recommended
Does it work

Cheers

Stuadh

--- In Doepfer_a100@yahoogroups.com , Bakis Sirros
<synth_freak_2000@y...> wrote:

> btw, it is really wierd:
> i have a modular with 18 PSU's and i have never
> noticed any interference in the audio outputs.
> are you sure that all the 6U cases are properly
> grounded
> but, of course, you should contact Roland Mayer
> direct.
> his email: technik@d...
> bakis.
>
>
>
>
> --- selfoscillate <synaptic_music@y...> wrote:
>
> >
> >
> > hello richard,
> >
> > i'd love to help you, but i can't.
> > i'm a nut when it comes to electrical things.
> > maybe you should email the technical
> > stuff at doepfer directly.
> >
> > best wishes
> >
> > ingo
> >
> >
> >
> > --- In Doepfer_a100@yahoogroups.com , "trebcavxx"
> > <richardbarton@c...>
> > wrote:
> > >
> > > You've highlighted a condition that's been present
> > in my own 75-
> > > module synth almost from the word GO - pulsating
> > modulation in the
> > > sound output. It occurs to a greater or lesser
> > degree in virtually
> > > ALL patches (I have 11 VCOs) - and takesd the form
> > of a cyclic
> > > variation in amplitude - usually giving the sound
> > a "woo-
> > > woo.......woo-woo........woo-woo" character rather
> > than a straight
> > > tremolo effect. As I say, this has happened from
> > the humble
> > > beginnings of a single VCO setup. I now have 5
> > seperate power
> > > supplies in the cabinet. I'm a bit doubtful that
> > LEDs are causing
> > it
> > > in my case, but would anyone have a cure for
> > either of our
> > problems
> > > I notice the previous mailing has been pretty well
> > ignored.
> > > Richard
> > >
> > > --- In Doepfer_a100@yahoogroups.com , "stuadh"
> > <stuadh@h...> wrote:
> > > >
> > > > Hi,
> > > >
> > > > I've been reading up on interference caused by
> > LEDs on the
> > > > power bus in the archives, a problem that I'm
> > having in my
> > > > homemade and commercial cases. I've minimised
> > the problem
> > > > by strategically placing the offending modules,
> > but there was
> > > > some discussion about including large capacitors
> > between the
> > > > power rails to help stop this problem occuring
> > in the first place.
> > > >
> > > > Has anyone done this, and was it successful
> > > >
> > > > What constitutes a "large capacitor" and what
> > type. Does the
> > > > polarity make a difference
> > > >
> > > > Yours Aye
> > > >
> > > > Stuadh
> >
> >
> >
> >
>
>
> =====
> Bakis Siros
> Parallel Worlds / Polariton
> Athens-Greece
> 1 group owner
> http://www.shimarecords.co.uk
> http://www.ward12.com
>
>
>
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