Looks like the power supply is new-style.

Furthermore, there is not enough space to mount the spring not in
parallel to the frame.

I'm now thinking to a ground problem : I tried with the springs unit
outside the suitcase : noise changes when I touch the RCA cable
anywhere between the module and the springs unit.

Perhaps a solenoid would filter 50Hz

--- In Doepfer_a100@yahoogroups.com , Florian Anwander
<Florian.Anwander@...> wrote:

>
> Hi
>
> if the suitcase has an old-style transformer (rectangular) it might

make

> sense to mount the spring not in a parallel direction to the frame. You
> may have to try a satisfying position by testing. Also you should obey,
> that not only the transformer will cause some hum. Also (neon or
> halogene) lights, powercables or wallwarts outside the doepfer case may
> induce the hum to the coils of the springreverb.
>
> Florian
>
> pfichoux wrote:
>
> > I was disappointed by the strong A199 hum noise in my brand new

Doepfer

> > A100 suitcase.
> >
> >
> > Perhaps I didn't care enough about Doepfer's home page warning :
> >
> > "The spring reverb system is connected to the A-199 module via 2

cables

> > with RCA phono connectors. As the reverb system is very sensitive to
> > magnetic fields it has to be placed in a big distance from the
> > transformer of the A-100 power supply - privileged in the left upper
> > corner of the A-100 frame. The reverb system is mounted with

screws and

> > nuts or double-faced self-adhesive tape. There has to be sufficient
> > space for the reverb system (about 20 x 7 x 5 cm).
> >
> > For frames that include the A-199 we recommend the usage of the new
> > power supply PSU2. PSU2 has much less magnetic radiation (because

of the

> > ring core transformer) that may cause hum noise in the A-199."
> >
> >
> > Nevertheless, I began to find another position for the A199 reverb
> > spring.
> >
> > Now it is mounted inside the suitcase, on the top/handle side of the
> > suitcase, open side of the spring reverb unit upwards, with

double-faced

> > adhesive tape.
> >
> >
> > Hum noise used to appear with a mix at 8 (9 o clock : almost dry
> > effect), now I can work easily with a mix at 5:5 (12 o clock).
> >
> >
> > Someday I'll try to build a full shield around the spring unit,

but I'm

> > already completely satisfied of my brand new A100 suitcase.
> >
> >
> > Cheers,
> >
> > Pierre
> >
> >
> > [Non-text portions of this message have been removed]
> >
> >
> >
> >
> > Yahoo! Groups Links
> >
> >
> >
>
> --
> Florian Anwander |ConSol
> Tel. +49(89)45841-133 |Consulting&Solutions Software GmbH
> Fax +49(89)45841-111 |Franziskanerstr. 38, D-81669 München
> email: florian.anwander@... | http://www.consol.de
>