New Tubes??

[m-m-m]

So, my friend has a Fender blues deluxe that he got a few months back. He gigs on it a ton. Anyways, the other day we were playing in his bedroom and I started noticing a ringing/buzzing sound on certain notes. We stopped jamming and after some trials I found the it to be centered around the F# on the A at the 9th fret. I was actually able to bend the note and get the noise to stop, and then start again when releasing the bend. Didn't seem to be dependant on the volume of the amp. I started fooling around with the amp a bit while he played. I don't have any practical experience with tube amps, but I've read a few repair books that talked a bit on the subject. At first I thought that it was maybe some kind of loose screw on the reverb tank, but I found that it seemed to be the preamp tubes. Didn't have a pencil around, but when I touched the tubes with my hands, you could hear a pop, and then the noise was gone. Came back when I released. Also, the noise seemed to dissipate when tilting the amp forward 20 degrees or so. Weird.

After some research I found this thread over at the fender forum that details some similar problems with the same amp. Basically, it talks about taking the amp out of the chassis and cleaning up some poor work (moving tie-wrap heads and poorly placed wiring harnesses). All that makes me a bit nervous - probably isn't as hard as it all sounds, but I don't have the amp in front of me. I was thinking that maybe we can just try swapping out a few tubes, as the issue may be microphonics but I know nothing about buying tubes. The manual to the amp says to only use fender tubes, but that sounds like BS. Cheap tubes run about $15 from guitar center, but is it worth it to spend more? Seems like some of the more expensive GT ones are just re-labeled sovteks that you can get for a lot less.

What do you guys think

[SoCalGuy]

Yeah, I'd like to hear back on this, too. jb

[SGspecial]

I wouldn't pay twice as much money for Groove Tubes to re-brand them.

It should have:
Matched pair of Sovtek 5881WXT
Three Sovtek 12AX7WA

All for around $58 ordered from Guitar Center.

[GT100]

...."Seems like some of the more expensive GT ones are just re-labeled sovteks that you can get for a lot less."....

That's not entirely true!

Groove Tubes are poorly QC'd and matched re-lableled Sovteks that you can get properly QC'd and matched from other vendors for a lot less!

Lloyd

[Tonesmiths]

Sounds like cone cry to me. Do you have an external cab to try it through?

[m-m-m]

Originally Posted by bender

Sounds like cone cry to me. Do you have an external cab to try it through?

not really - he's got a mesa roadster combo that (theoretically) we could try to connect to the speaker out of the fender ...
but why would the noise stop while i put my hands on the tubes?

[Rambergwest]

If you can quiet the problem by touching the tubes you might try checking the chassis screws of bolts to see if you can make it go away with a little tightening. Essentially the note you indicate is being picked up by the tube/s and if you can alter dampen the mechanical pathway to the tube you may fix the problem.
Hey, it could work

[Rambergwest]

You might also try the speaker mounting screws, same idea as chassis only you are looking for a loosness that just shows up at your frequency.

[Tonesmiths]

Originally Posted by m-m-m

not really - he's got a mesa roadster combo that (theoretically) we could try to connect to the speaker out of the fender ...
but why would the noise stop while i put my hands on the tubes?

Sorry, I missed that part. The external cab might be a good way to see if it's a vibration related problem though.

[clumpster]

If you don't know what your doing with amps..don't go poking around in there when it's on or you'll be in for an unpleasent surprise.
Stick to replacing the tubes and let a tech do the rest.
There are many tubes that can be used in that amp..from cheap Russian stuff (basically all the rebranded stuff anyway..Mesa, Fender, Sovtek..blah, blah) to very expensive but good NOS. Send me a note and I give you some straight info..I sell NOS tubes and have been for years..and I'm not going to try to sell you anything.
CW

[nrandall85]

Exact same thing happened to me last week. Bassman RI with Winged C's (only about a year and a half old tubes.)

I ran the amp, and like you found a few "bad" notes. I think mine were mostly on the low E string.

I poked around with the tubes, and the one on the right ended up being the cause. Double checked in another amp.

I put in a trusty set of Sovtek 6L6WXT+'s. After first being a little pissed that they sounded much better than my Winged C's, I was happy the noise was gone.

[m-m-m]

Thanks for all the responses. I'll check with the owner of the amp and see how he wants to proceed. I'll post back an news for those interested.