"Rob" wrote in message
...
Iain Churches wrote:
"Rob" wrote in message
...
Fleetie wrote:
Hi.

While I'm here, does anyone know the usual cause for a valve amp
constantly "rustling" out of one channel? Mine is doing it
intermittently and sometimes loudly, out of the left channel.
Is it likely to be a resistor burning up, or something about
the valves? Is it likely to be in the output stage valves or
cathode resistors, or...? It's starting to drive me nuts!

Is this the kind of symptom that tends to always have the same
cause?

Thanks for any pointers.
In my limited experience (er, once), it was down to a faulty valve. One
of the big ones.

It can be all manner of things, so you need to make a list and start at
the beginning. It might be a dry joint somewhere. Whatever it is, it
can be found with systematical searching. The hi-tech methods of
a) wiggling and b) tapping usually provide the answer.


Agreed. The beginning for me, though, is to look at the valves, see if one
looks a bit peeky, and change if there's doubt. As I say, it worked for me
so it may work for Fleetie. One of the big chunky valves rather than one
of the tiddlers in my case. That, along with the wiggle and reseat, is the
extent of my system.

Yes. Your methodology is sound. I have the luxury of two
AVO Mk IV valve testers in the workshop which I share,
but still, a visual inspection is a good first step. In my experience,
rustling is usually associated with small signal valves, (miniature
nine pins in particular) so "swoppin an' listenin' usually finds the
culprit.

Iain