> In principle there is absolutely no reason why one couldn't short
> either of the two signal pins to ground, save that the common mode
> rejection would of course negated.
Rob,
Going back to my original "geek" email, if the input is fully floating
as with a transformer input then you can ground one leg, but only if
there is no phantom power supply.
With a balanced line using a centre tapped transformer, grounding one
line would short circuit the signal. However most portable "balanced"
inputs have independent input circuits when you would get away with
shorting one of them.
With a phantom powered balanced line input, shorting one powered leg
to ground could give all sorts of problems and this is why I suggested
connecting a well designed (or otherwise) :-) unbalanced mic across
+ phase and centre ground.
David
David Brinicombe
North Devon, UK
Cogito cogito ergo cogito sum - Ambrose Bierce
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