Even if they are, try a capacitor from xlr ground to case.
Brian

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"Clive Arthur" wrote in message
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On 13/04/2019 14:53, Dave Plowman (News) wrote:
snip

Both amp and crossover are fully enclosed in ally cases. Putting a hand
near then from any direction gets rid of the buzz. I'm thinking to do
with
body capacitance. Somehow.

Are these cases grounded?

Cheers
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Clive