Hi Chuck,
Well I guess that rules a switching supply out as the reason, but I note from searching the archives that a number of people have experienced problems using Power One supplies of one type or another, though most seem to have been problems where an LFO or the like 'modulates' the rails, which is then being picked up in other modules.

I'm afraid the best I can suggest now would be to try and find another supply to run them on, and see if the problem goes away, which at least will pin-point what is to blame, if not giving the exact reason...

Poor grounding of course is another perennial cause of grief, so it would be worth checking connections there.

Tim

--- In Doepfer_a100@yahoogroups.com , "hamzzzald" <hylaster@...> wrote:
>
> Thanks Tim. It is a linear supply, Power One HAA15-0.8-A
> -c
> --- In Doepfer_a100@yahoogroups.com , "Tim Stinchcombe" <timothy@> wrote:
> >
> > Hi Chuck,
> >
> > I've not experienced anything like that myself, but one often hears of trouble when using a 'switched' power supply as opposed to a 'linear' one, so do you know which category the Power One supply is (or maybe a link to a description of it)
> >
> > Tim
> >
> >
> > --- In Doepfer_a100@yahoogroups.com , "hamzzzald" <hylaster@> wrote:
> > >
> > > Is anyone familiar with his symptom: A filter, once connected to my PSU, develops a very pronounced hiss at the output stage. The level of hiss is independent of the input signal volume. The filter still functions other than this noise. The filter in question is a A-106-1, but I have had the same problems with a couple of Synthesizers.com diode ladders (which I realize aren't designed to operate on +-12 but this shouldn't be the issue, right ) There is a 101-2 and a Bananalogue Serge VCS on the same bus that seem to be fine.
> > >
> > > I am running my system on a Power One supply, +/12v 1 amp. Today I checked the supply and the bus board and all the rails are delivering what they are supposed to.
> > >
> > > Thanks!
> > > chuck
> > >
> >
>