Odp: [sdiy] More ground questions

Tim Ressel madhun2001 at yahoo.com
Tue Aug 6 20:54:02 CEST 2002


Roman,

If module A is connected to module B, and mod B has
some high-current digital switching going on, and the
two are connected with a patch cord with thru ground,
the the digital switching current might wind up on the
patch cord shield, and impinge itself on the signal
conductor. No amount of beefy grounding on the noisy
module will guarantee success. The best thing is to
break the shield wire in the patch cord so ground
currents cannot flow.

Actually, the BEST thing would be to go balanced on
the connections. A little extra cost, which you might
be able to deduct on your taxes as insurance...

--TR


--- Roman <modular at go2.pl> wrote:
> I'd like to add one comment/question to this
> thread.
> What if all jacks' grounds are connected together
> at the panel, all panels connected with cabinet
> rails,
> and all of this is connected to signal ground at
> power
> supply only?
> I have done it this way and it seems to work good,
> although my modules count isn't impressive, so I
> can't
> tell for sure. Basically I treat modules as they
> would
> be connected with bananas, but instead I'm using
> 1/4'' TS. Any ground loops made of patchcords
> shouldn't cause problems, should they?
> 
> Roman
> 
> ----- Original Message -----
> From: Scott Stites <scottnoanh at peoplepc.com>
> To: <synth-diy at dropmix.xs4all.nl>
> Sent: Tuesday, August 06, 2002 5:41 AM
> Subject: Re: [sdiy] More ground questions
> 
> 
> > Thank you all for the thoughts and discussion,
> on-list
> > and off, on grounding techniques and pitfalls.
> I feel
> > better armed now to go ahead and design the
> cabinet,
> > and a better understanding of what to do if I
> run afoul
> > of noise in the system.
> >
> > *Obviously it appears that a lot of problems can
> be
> > headed off in the module design itself.
> >
> > *A star ground ground looks to be a good
> > implementation.
> >
> > *Ground is best if all points meet at the
> 'ocean'
> > (coupling caps in the power supply).
> >
> > *Shielded cables for audio and CV signals must
> be
> > considered in the design.
> >
> > *'Dirty' and 'clean' power supplies can be used
> for
> > 'dirty' and 'clean' signals with 'dirty' and
> 'clean'
> > grounds for the respective power supplies
> (sounds
> > especially helpful if a number of LED's will be
> used).
> >
> > *Isolation of connectors on module panels
> through the
> > use of non-conducting shoulder washers is
> something
> > that can be tried as well.
> >
> > I appreciate the information greatly. This list
> rocks!
> >
> > Scott Stites
> >
> >
> > ====================
> > Ken Stone wrote:
> >
> >
> > > >...if the rest of the design and grounding
> is done
> > > correctly as well.
> > > >In most cases the builder will blow the
> concept
> > > somewhere and get no
> > > >benefit.
> > >
> > > Often as soon as a patch cord is plugged in
> between a
> > > clean and noisy
> > > module, you've blown it anyway. :)
> > >
> > > I think a good way to separate LEDs from
> ground is to
> > > run them between + and
> > > - rails - on separate "noisy" power
> rails.
> > Ground can
> > > stay shared that way.
> > >
> > > Ken
> > >
> >
> __________________________________________________
> _____________________
> > > Ken Stone   sasami at hotkey.net.au
> > > Modular Synth PCBs for sale
> > > <<a
> >
> href="http://mail.peoplepc.com//jump/http://www.bl
> aze.net.au/~sasami/synth/&gt">http://www.blaze.net
> .au/~sasami/synth/&gt</a>;
> > > Australian Miniature Horses & Ponies
> > > <<a
> >
> href="http://mail.peoplepc.com//jump/http://www.bl
> aze.net.au/~sasami/&gt">http://www.blaze.net.au/~s
> asami/&gt</a>;
> >
> > ________________________________________________
> > PeoplePC:  It's for people. And it's just smart.
> > http://www.peoplepc.com
> 


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