#1
Purchased 2 fender blues juniors second hand.

They have different sounds; one seems to be a little on the harsh side on the attack (but can be toned down with treble) and has a nice clean sustain.

The other amp has a nice warm attack tone but at about 2 seconds on the sustain it cuts a little in and out and starts a mushy fuzzy harmonic overtone type noise (similar to when a sound is active when you turn an amp off and the power dissipates and the sound starts to die). The sound does not cut out but sutains this slight crappy overtone noise till the sound fades and the white noise of the tubes is left.

Different volumes and gains were experimented with and same problem. They both have Groove Tubes (sovtek) and i swapped the tubes with the amps and the problem did not go away. This leads me to rule out a problem with it being the tubes.

I like the initial tone of the problem amp, just cant get a clean sustain after about 2 seconds. Anybody know what a bad rectifier sounds like?? it is a solid state rectifier. Any other things to consider before getting a shop to have a go at it.

Did not know if to post here or the DYI forum, but hope some here may have a solution.

thanks
dmodal
#2
When you refer to them having "Groove Tubes (Sovtek)" I'm guessing you're talking about the preamps? Groove Tubes makes their own power tubes.
Quote by Dave_Mc
I've had tube amps for a while now, but never actually had any go down on me
Quote by jj1565
maybe you're not saying the right things? an amp likes to know you care.





www.SanctityStudios.com
#3
Sounds like a speaker issue to me.
A bad rectifier sounds like this:
" "
You can also try a 47pF cap across the phase inverter anodes to reduce fizz. There are some other methods but they elude me at the moment.

Edit for matrixclaw: GT makes most of their own power tubes, but I don't think the EL84 is one of them.
Last edited by Roc8995 at May 21, 2008,
#4
actually both the EL84/6BQ5 and the 12AX7WC are sovtek -made in russia and just stamped with fender groove tube.

the speaker is not a problem a failed to mention the rule out on the speaker with the external cab.

the sound is great for a few seconds and then the weird tone starts coming on into the mix as it sustains. i have never heard this before on any of my tube amps before and the quick tube swap did not fix it.

just hoping to find something on the tube path the could possibly be a easy fix with a replacement part
#5
Ah, I keep forgetting the Blues Junior runs on EL-84s, I keep thinking they run on EL-34s for some reason, though I guess that wouldn't make sense since the wattage wouldn't exactly add up right
Quote by Dave_Mc
I've had tube amps for a while now, but never actually had any go down on me
Quote by jj1565
maybe you're not saying the right things? an amp likes to know you care.





www.SanctityStudios.com
#6
Quote by MatrixClaw
Ah, I keep forgetting the Blues Junior runs on EL-84s, I keep thinking they run on EL-34s for some reason, though I guess that wouldn't make sense since the wattage wouldn't exactly add up right

it runs on el84s??????!!!!?!?!?!??
nnnnnnoooooooooooo, i was gonna buy one. not now. i want a nice low powered 6l6 amp. dang it.