[sdiy] Oberheim SEM power

[Magnus Danielson]

From: "doof" <doof at cox.net>
Subject: Re: [sdiy] Oberheim SEM power
Date: Thu, 20 Jan 2005 19:33:54 -0500
Message-ID: <000901c4ff50$e30b1f40$6501a8c0 at tomputer>

> It looks like I'm stuck with +-18.5V unless I want to interfere with normal
> operation.
> 
> Thanks everyone.

May I point out that it was a very simplictic mod to change the Formant PSU
to do +/- 18.5V instead of +/-15V. I think I just changed two resistors and
then I was done. Works like a charm.

There is even a specific point about the +/- 18.5V bus-supply. The coupling
between SEMs and also other devices over the PSU bus is much lower by
individual regulation. The internal regulation in the SEM is also cleverer than
you first might think, since the -15V line is traceable to the +15V line, which
avoids another trouble you might have.

My recommendation is to go with the flow and not work against the quite good
engineering behind the SEM supply strategy.

Cheers,
Magnus

> 
> > Theres a power supply from a Four Voice on ebay now - item 3776339211
> >
> > --- doof <doof at cox.net> wrote:
> >
> > > Greets all,
> > >
> > > Has anyone successfully used an Oberheim SEM module at +-15V?
> > > Web sources say +-18.5V -- but it would be nice to integrate it with a
> > > modular and only have 1 power plug.
> > >
> > > Thanks.
> >
> >
>