Tube amp cutting out/scratchy sound after getting tubes tested

[micah_jm550]

Hey everyone,

I took my Blackstar HT40 to the music store to get the tubes tested (amp was noisy but the tech said it was just because of the gain being turned up). Tube tester read that the preamp tubes were at 75% and the power tubes at 95%.

I get home, plug in, clean channel is fine. However, when I switched to the gain channel, I get this fuzzy sound and almost like this slight tremolo effect, and it cuts out and the volume increases and decreases.

I had none of these issues before having the guy take the tube out, test it, and put it back in. I shoulda just left it alone lol.

I jiggled the preamp tubes and the one felt a bit loose compared to the other. Maybe the preamp tube for the gain channel wasn't put back correctly? That's the only thing I can think of. What do you guys think could've caused this? Thanks!

[Top-L]

Hey everyone,

I took my Blackstar HT40 to the music store to get the tubes tested (amp was noisy but the tech said it was just because of the gain being turned up). Tube tester read that the preamp tubes were at 75% and the power tubes at 95%.

I get home, plug in, clean channel is fine. However, when I switched to the gain channel, I get this fuzzy sound and almost like this slight tremolo effect, and it cuts out and the volume increases and decreases.

I had none of these issues before having the guy take the tube out, test it, and put it back in. I shoulda just left it alone lol.

I jiggled the preamp tubes and the one felt a bit loose compared to the other. Maybe the preamp tube for the gain channel wasn't put back correctly? That's the only thing I can think of. What do you guys think could've caused this? Thanks!

I don't know what is wrong with your amp and I hope you can figure it out.

I want to point out that there are some "amp techs" who are utter clowns who would rather just take your bench fee without doing any work. About ten years ago I took my JSX to a local amp tech because the power section was making a buzzing noise. He said he had it on the bench and "nothing was wrong". He said, "these are high gain amps and they make alot of noise." Also, "Its a Peavey, its not a high quality amp."

I researched the type of noise and suspected it was bad caps. I ordered caps from Peavey, did the cap job myself, and the amp was dead quit after that. The original tech basically stole my $100 bench fee and either didn't know how to diagnose or perform a cap job, or just didn't want to do it.