TH30 Volume Loss Trouble Shooting (Potential Tube Issue)

[hdunc95]

Hey guys. I bought a used Orange TH30 head used (it was in very good condition) about two years ago or so. I take good care of it and correctly connect it to my 2X2 Avatar Cab (8ohms) every time I play. However, I gig with it so it does get bumped around some.

Here's my problem. My amp had very strange volume loss when I plugged it in during practice about two days ago. When I turned my amp on it started out at a relatively normal volume then quickly fell to a whisper for both the clean and dirty channels. There was also a hissy/fuzzy volume fluctuation when I would switch back to stand by. I tried out three working instrument cables to make sure it wasn't a bad cable issue but that did not solve the problem. Based on my research, it seems like I may have a faulty or loose power tube. My plan is to go ahead and replace them and see if that helps. But my main question is, are the problems my amp is exhibiting indicative of a problem with the EL84s?

I appreciate all help I can get, this will be my first attempt at a retube.

[Les Paul Lover]

Sounds like it could possibly be a valve issue, especially if you haven't changed the valves yet, have gigged and practiced with it regularly.

Certainly the valves are the 1st p lace I would look at.
Since the problem exists on both channels, it should either be down to the power valves, (EL84s), or the Phase Invertor (or PI 12ax7/ecc83), essentially a valve common to both channes.
power valves wear out much faster than preamp valves, so the EL84s are a good place to start, though I would get a few 12ax7 too just in case.

Those EL84s dont need biasing, so you can replace them yourself too.

[hdunc95]

Les Paul Lover, thanks for the quick reply, I think I'll switch all the EL84s, I've meant to to do for awhile now. Any recommendations on reasonably priced quality EL84s? Was looking at a set of JJs that were fairly inexpensive.

Also, if it is a problem with the one of the 12Ax7s, do I need to be worried about biasing those specifically or can I switch them out like the EL84s?

[Les Paul Lover]

Yes, preamp valves never need to be biased.

[pedecamp]

Pull each tube and reseat them in the socket before buying new ones to make sure its not just a bad connection. You can also spray the tube pins with Deoxit electronic cleaner to clean them too.