New Amp...Tube Questions

5L. · 05-13-2003, 05:22 AM

Actually it was just gentle tapping on the top of the amp. It's weird, because i walk around the amp and the vibrations also seem to cause some noise.

Well I replaced the tube all the way on the left, no idea which one that is (the user manual doesn't seem to mention) but suddenly the amp got a LOT louder! I mean now, I am playing with Volume on 2, Master 2, Lead 1, and I can hear it loud and clear.

nate95366 · 05-13-2003, 07:57 AM

I'm assuming you meant the 12AX7 preamp tube all the way over on the left in the line of 5... *goes to look for his schematic*...*can't find his schematic*...

My guess in your case is that that's the preamp tube that sends signal to the "effects out" port, and since your amp is always working by means of the effects loop (unless you've had that repaired by now), that's the reason for the difference in output.

Nate

Benny Hicks · 05-18-2003, 02:06 PM

Alright, I had some issues with my amp so I sent it back to Carvin and they shipped me another one. Low and behold, this one seems to have a different problem. When I first plugged in and started playing, I immediately noticed that the low- to mid-range is a lot louder than the high-range. I mean, not just a little bit, it's obnoxiously loud. When I strum hard I can definitely hear some vibration going on in my amp and I'm not really sure what's going on. Is that proof that my tubes are messed up, or what's the deal? Any help would be really nice.

Ben

nate95366 · 05-19-2003, 06:45 AM

Quote:

I mean, not just a little bit, it's obnoxiously loud.

This is what every amp would sound like without a tone circuit. It's very reflective of the signal that electric guitar send. I would guess that unless it's something really simple (like the tone controls on your guitar), that there's some issue with the tone circuit in the amp. As far as "rattle" goes with tube amps, sometimes you have to turn into a detective. When my amp rattles, I check things in this order:

1) Is the reverb knob up too high ?

2) Are all the tubes seated well in their respective sockets? Warning: don't grab a hot tube with bare hands unless you enjoy running cold water over said bare hand for a long time to relieve the second-degree burn you'll get.

3) Are the screws that hold in various components nice and snug. Some common culprits: The screws that hold the reverb tank to the chassis/cabinet (wherever it happens to be mounted if it's got a tank), The screws that hold the chassis to the cabinet. Sometimes faceplates rattle too. One guy I know had trouble with his faceplate rattling, so he wedged a "heavy" pick in between the baffle-board (which has the grillecloth wrapped around it) and the faceplate.

Basically, it just takes a methodical trouble-shooting approach to figure out what's going on in a tube amp PLUS the smarts not to do anything that could get you shocked to death (like prodding around inside the chassis or poking inappropriate things into tube sockets and such...)

Nate