"Rob" wrote in message
...
I've got an old ( 5yrs) pair of recently obtained ATC SCM7 speakers.
Something sounded wrong from the off, and I think I've isolated it as a
faulty tweeter. One is distinctly louder than the other, and I can't
reliably differentiate the LF units, which seem much the same.

I've reached this conclusion by just connecting up the HF or LF connectors
on the speaker terminal panel. Swapped across channels/sources/amps to
rule out other issues.

Anyway, and assuming this test is reasonable, what might the problem most
likely be? Tweeter or crossover? And sourcing ATC units? Anything like the
Dynaudio closed shop of recent experience? I will contact them at some
point . . .

And another thing. I was doing some testing using a Windows XP laptop as
source - useful as I can use the software balance control in the native
sound mixer app. But how are you supposed to centre it? Seems very easy to
have it a click or two off centre.

Rob

Try swapping the polarity of the input to the quiet tweeter (tweeter only!).