[sdiy] Grounding of inputs/outputs for modules

Andre Majorel aym-htnys at teaser.fr
Sat Aug 4 00:37:45 CEST 2012

On 2012-08-03 11:40 -0700, David G Dixon wrote:

> > I seem to recall you're a materials type, so pardon the 
> > question, but doesnt aluminum oxidize?  Can a mechanical 
> > panel to socket connection be trusted electrically long term? 
> >   These are dis-similar materials as well, no?
> Aluminum oxidizes instantly when exposed to air to form an
> invisible nanolayer of aluminum oxide, Al2O3.  This oxide
> layer passivates the aluminum perfectly.  As long as this
> layer isn't exposed to acid, the underlying aluminum will
> never corrode.  That is the secret to its widespread use, even
> in highly oxidizing environments.

But alumina is an insulator. So to make reliable electrical
contact with aluminium, you must pierce through the alumina
layer and (this is the difficult bit) somehow keep oxygen out of
there FOREVER.

> As far as I know, none of the panel-to-jack connections has
> ever failed in my modular.  If it were a problem, I could
> easily wire up all the jack rings, but it simply doesn't seem
> to be necessary.

How would you know if one did ? As all of your modules share the
same 0 V reference through the power supply, the jack sleeves
are only used for shielding. Loss of shielding would not be
obvious thanks to the high levels and low impedances. The Serge
modular is proof of that.

The only failure you might notice is in the socket that goes to
your mixing desk. Even then you might not if the ground is tied
to earth on both sides.

André Majorel http://www.teaser.fr/~amajorel/

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