On Monday, December 4, 2017 at 11:20:13 AM UTC-5, wrote:

How do we debug a scratchy sound?
We can isolate it with the balance to a single speaker.
But is it the speaker? Or something else?


Interchange the wires at the speakers - you'll prove that it's the
speaker and not the stereo or wiring.
Pull out the bad speaker & look for a tiny tear - try fixing it -
http://www.300guitars.com/300s-tips/...speaker-cones/
or shop for a replacement.
John T.


Keep it simple - introducing more variables - such as a different
third speaker and its wiring .. etc just confuses the issue.
.. especially when a simple and straight-forward trouble-shooting
method is available.
John T.

So, it's not nonsense to use another speaker that may be available to
test, it's just that it's not *your* method. It may be easier and
simpler to use another speaker. Are the wires and connections to
the other rear speaker available or is further disassembly required?
Not unusual that you have to remove the speaker before you can get
to the wires. So now you have to remove the other speaker.
And even if you don't have to remove the other good
speaker, you almost certainly aren't going to just move the wires from
it to the other side to run the test. The wires typically are not
going anywhere. Given that, I don't think
it's nonsense to use another speaker which can be quickly connected
with some jumper wires to test. I have a few here that I could easily
use instead of pulling the other speaker out. If he wants to pull the
other one, fine. But it's clearly not nonsense to suggest using another
speaker.