#1
Hey guys,

I've been lingering around this site for a while and learned lots of things, so I figured I might as well start asking my questions here too

So heres the deal...I bought a new DRRI 2 weeks ago. I left for vacation and returned to find that one of the preamp tubes (the one on the far right when looking at the back of the amp) had gone microphonic. The amp had a ringing, bell like sound when I knocked on it or turned it up past 8. I replaced the tube, but now there are new problems.

When I play anywhere above 5-6 on the amp, there is a rattling coming from somewhere in the amp (I moved it into 3 different rooms to make sure it was nothing in the room rattling). It is especially bad when playing the low E string. I also tightened all the screws I could see on the cabinet. Also, the amp distortion has become very thin and fizzy. It is much worse with pedals (Keeley TS808 and Fulltone OCD). PS, I run my pedals with the level almost dimed and the gain around 8-9 O'clock.

I have been searching threads for a couple hours and found no answers, but some possibilities.

What has gone bad? Another preamp tube? Power tubes? Something else?

I really appreciate your guys' help for a newbie around here! Thanks!
Phil
#3
Pull out the tubes and plug them back in again.
Gilchrist custom
Yamaha SBG500
Telecasters
Randall RM100 & RM20
Marshall JTM45 clone
Marshall JCM900 4102 (modded)
Marshall 18W clone
Fender 5F1 Champ clone
Atomic Amplifire
Marshall 1960A
Boss GT-100


Cathbard Amplification
My band
#4
Still no luck...I pulled them out and put them back in and the problem is still there. I also tried to make the noise go away by putting pressure on a tube one by one to try to isolate it to one tube, but the noise was still present.
Could this be a tear in the speaker? Or would the noise be there at low volumes too?

I'm getting frustrated!!!
#6
Yes, but I think I may have found the problem.
When I play, the two power tubes have a purple light that flashes on when a note is being sustained, but then vanished when i mute the string. Is this a bad sign or something normal?

PS--I found that the noise is the worst when playing the 12th fret on the low E

Thanks!
Phil
#7
Purple is just impurities flourescing on the plate. It's nothing to be concerned about. The only colour to worry about is red.

Here's how I tackle your problem. Use a wooden spoon as a stethoscope to locate where the rattle is actually coming from. Stick the spoon end to your ear, they make a fine stethoscope. It's an old mechanic's trick, well apart from it being a spoon; they use whatever is long enough in the garage for the job.
Gilchrist custom
Yamaha SBG500
Telecasters
Randall RM100 & RM20
Marshall JTM45 clone
Marshall JCM900 4102 (modded)
Marshall 18W clone
Fender 5F1 Champ clone
Atomic Amplifire
Marshall 1960A
Boss GT-100


Cathbard Amplification
My band