Folks....am facing issues with my Blues Junior III.....strange harsh brittle kind of white noise with every note played...very similar to a speaker that's gone bad....I've tried:

1. Changing the tubes
2. Running it through another cab to check for an expired speaker
3. Disconnecting the reverb tank
4. Checking for rattles from fixtures to the chassis (seems to be a common BJ issue)

Nothing's worked so far...

Unfortunately (knowledgeable) tube amp technicians are an alien concept where I live, else I'd have happily roped in a techie to diagnose and hopefully resolve this

Can anyone help please?

could you get a video of it for us? that would help out a lot.
trashedlostfdup - good idea, will do so....will take me a couple of days as I'm currently on the road...thanks!

that is the easiest way to go. most the time a video will be more helpful than spending twenty minutes of trying to phrase what you are hearing and us still not knowing what you are describing. lol. it happens all the time. especially since you have covered the bases already.

we will get it figured out.
I would bet the tubes are rattlling in the sockets. Happened with my Blues Deville until i got some heat resistance foam to go round thestubes. The newer fender range comes with this foam all ready from the factory.
I'm betting it's the same thing I had with my Pro Jr. Even though it was made in the US, not China, the factory soldering job was crap, cold solder joints on every tube socket, I had to do some soldering and now it sounds great. Harsh, buzzing sound, almost like a blown speaker. Mine didn't do it till I got the volume up to around 5 (it has 12 max).

Try this. Turn it on, nothing plugged in, volume at least 3 or 4, or wherever it is when you hear this, reach in the back and wiggle each tube and see if it happens. Wear gloves or use just the glass tip of the tube, it won't get very hot. I thought loose tube sockets, it sounds exactly the same. That's because the same thing is happening but in a different location. Vibration is causing the loose solder joints to bounce around when you play it.

If that looks like your problem, take the circuit board out and look at the solder joints with a magnifying glass, you will probably be able to see a slight ring around each one. That's a cold or broken loose solder joint, it's vibrating and causing some nasty noises, and that's why I got my Pro Jr for $30 at a yard sale...the bozo just didn't tell me it had a problem...

The fix is not hard if you know how to solder, reheat each solder joint and melt it back together again. Mine plays great now, I used it Saturday night at a gig and will be using it tonight at band practice.
Hmmm...I wonder what this button does...
Last edited by Paleo Pete at Jun 29, 2016,
Folks, thanks for the responses

As suggested, here's a video of the amp (Vol ~6, Master ~3)....I hope you can make out the buzz that follows the lower notes (in fact I realise I should have described it more as a buzz than a rattle)....this is not normal saturation, the amp should be clean at these levels....any more observations will be most welcome...thanks!

CRAZY THOUGHT - but are you %100 sure it isn't fret noise? just tossing that out, an improper set up can lead to a lot of "amplified issues". Not saying that's what you have.

Your video comes back as private, BYW. I'd love to watch and see if I can help, but I think you'll need to adjust the settings.
1981 Gibson Les Paul Custom (Black Beauty)
1980 Marshall JMP 2204
Jonny Ryan MacThanks for the response, I have changed the privacy settings, would really welcome any suggestions

I've ruled out fret noise as this seems to happen with my other guitars as well on this amp, and my other tube amp don't act up like this with the same guitars

hmmmm. could that be a rattling spring in your reverb tank?
trashedlostfdup I'll check again but my hunch is no, I'd tried disconnecting the tank and it didn't seem to sort out the issue....
Quote by 18WCleanBoost
trashedlostfdup I'll check again but my hunch is no, I'd tried disconnecting the tank and it didn't seem to sort out the issue....

a long time ago i had an amp that had a similar problem. the bass from the speaker rattled the tank and made the tank bang around and make all sorts of noise. i ended up just pulling the tank (its around here somewhere, lol), and it stopped.

i would go through the whole amp and make sure all of the screws/bolts are tight, especially the speaker and chassis mounting screws.

after all of that what i would try would be to pull the entire chassis (leave the speaker in the cab) and try it and see if it still happens. if it does, you could eliminate either the chassis or the cabinet making noise, or if it doesn't you know it is something with the two attached.

good luck!

Thank you guys for your help....I tried all of this and eliminated mechanical issues....I managed to rope in someone to look at the board in some detail and test each component with the help of a schematic....it turned out to be an electronic issue after all...let me see if I can reproduce his explanation correctly....some bad resistors caused an imbalance that led to one tube heating up and clipping much faster than the rest of the system (whatever that means)...anyway I flung the good man a purse of gold and went on my merry way, with a properly working BJ III...all's well that ends well....