Doepfer

Hows about live components touching the earthed rack itself?
  ----- Original Message ----- 
  From: stuadh 
  To: Doepfer_a100@yahoogroups.com 
  Sent: Friday, December 03, 2004 11:02 AM
  Subject: [Doepfer_a100] Re: Power Source interference



  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
  > [Doepfer_a100] group owner
  > http://www.shimarecords.co.uk
  > http://www.ward12.com
  > 
  > 
  >             
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