TwinReverb
First Lieutenant  Posts: 2 Registered: 1/12/2008 Status: Offline
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posted on 1/12/2008 at 13:58  |
My new Fender Twin Reverb was great the first day I used it which was at
night after it arrived. I played with it for about one hour at low volume,
different settings then practiced for awhile. The next day in the afternoon
I turned it on and noticed on the Vibrato channel that is was
humming/buzzing at low volume and at 5 and up to 10 on the knobs was
buzzing loud so I left it at 10, without a guitar plugged in, and it would
make a few different noises like some crackles at times, and a high pitch
frequency noise in the background. The Normal channel was absolutely quite
at first until about 1/2 hour into diagnosing the amp it too started up
with some noise.
I happen to have 4 new 12AX7 tubes, stuck them in with no change in the
buzz/hum.
What I am thinking is (hopefully) that after the 4 6L6 power tubes got hot
the first time I used it, after they cooled down and the next day when I
fired it up, one was going bad right away. I am hoping it is a power tube
issue, bad tube.
I tried the hum balance with no real change in the noise. I also tried
using a different outlet incase it was a ground issue but it wasn't there
the first day so I figured it's not a ground issue and found no change in
the noise.
I live really far from any service center (3) hours or more, so the safest
way and cheapest way for me to try to figure out what happening is first
buy a matched quad set of Fender 6L6 tubes and replace all four of the
power tubes and see if that takes care of it. If it doesn't at least a I
have new set for later and know I have to send it off or drive 3 hours to a
service center.
What do you think about my idea? Do you have any suggestions?
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TwinReverb
First Lieutenant Posts: 2 Registered: 1/12/2008 Status: Offline |
posted on 1/13/2008 at 13:51, Reply 1 |
Here's what I have found out. If you look straight on at the rear panel,
the tube line up is L to R, 4 large power tubes, and then 6 small pre-amp
type tubes. The tube second from the far right is a 12AX7. The chopstick
made a real loud noise on that tube. Non of the others had any noise. So I
happen to have a 12AX7 from another Fender amp and stuck it in, the same
loud noise! I figured maybe that tube was bad. But I happen to have a
number of Yugoslavian ECC-83 tubes which are supposedly like a 12AX7. I
tried two of those and the same loud noise when I hit that tube with the
chopstick! They ALL couldn't have been bad tubes, at least before I stuck
them in the amp.
So what the neck is going on. Is it blowing the 12AX7 tubes right off when
I turn on the amp? Or does that tube socket have some problem? Anyone ever
heard of this? The amp makes a lot of odd noises from the tubes I tried in
there but they all make a loud noise when hit but non of the others do? Is
my amp a lemon or what?
I just did one more test. I switched a 12AX7 from another socket on the amp
that I knew was good. I stuck it in the second to the far left socket. I
then took the original tube that I thought was bad and placed it in the
socket I just removed the good tube from. The chopstick made the tube I
just placed in that second to the far left socket make the loud thump
noise. It is for certain that something is wrong with the tube socket or
whatever circuitry is involved with that tube socket.
Does anyone have any more advise before I call a service center? I live at
least 3 - 4 hours from one and it's really a bummer I have to make that
drive. Shipping would not only be expensive but dangerous for the amp as
most of you know from UPS/FedEx heavy amp shipping experiences.
Once again thanks. I just bought this amp! It's not a really happy first
time experience.
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