# Do I need to replace 2 EL84 tubes



## Verne (Dec 29, 2018)

The last couple of times I played my TM36, I notice a very audible buzzing from the speakers. I don't recall it being anything but crystal clear. I have tried unplugging everything and only plugging the TM36 into the wall. I left my phone upstairs, I even kept the room lights off (LED bulbs). I tried different cables on the guitar, the amps and even a pedal cable to the in/out on the effects loop. I have literally tried everything I can think of. I tried the TSC thing on the back. I put a pick in and pushed. All 4 lights blink 10 times, but this morning, they all blinked, but the 2 right most did not blink the last time with the other 2. I also noticed the 2 that match to those lights were not glowing as brightly at the top of the tube like the other 2. Is this likely the culprit for the buzzing? It's not a hum, or interference that I can tell, but a definite buzzing. My other 2 heads do not buzz, but they are SS.


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## oldjoat (Apr 4, 2019)

could be filter caps / dead spider across high voltage/


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## Budda (May 29, 2007)

I have a pair you can try.


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## Verne (Dec 29, 2018)

That's be awesome @Budda Thanks very much.


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## DaddyDog (Apr 21, 2017)

I've made a point of building up a stash of tubes for just such an occasion.


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## Verne (Dec 29, 2018)

This is my first tube head so I am at the beginning of any stash scenarios. Once I determine the problem, may order a set of 4 and keep the 2 "good" ones from this one. If it is a tube issue.


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## Verne (Dec 29, 2018)

I forgot to ask if it is okay to continue using the amp or not. I can't say for sure that the volume has dropped, as I use the power soak differently depending on when I play. 

I assume if it turns out to be a bad (or 2) tube when I test with the tubes borrowed from @Budda, that I should replace all 4 in a matched set? Or can I replace just 2 in a matched pair? If it is a power tube, I have read that it doesn't require matching and all 3 could be different and there are no repercussions. Of course, I am more than willing to be corrected if incorrect.


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## Verne (Dec 29, 2018)

I have now taken it apart and tapped on all the tubes. The middle 12AX7 makes a fairly audible "tink" when tapped. The covered one makes no noise, and the other uncovered one makes a very faint tink when tapped. The power tubes make no noise at all when tapped. The left 2 still do not glow as brightly as the first 2 do when warmed up. Will preamp tubes cause a buzz when not on standby?


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## jb welder (Sep 14, 2010)

When you have your guitar plugged in and turn the guitar volume & tone all the way down, still buzz? Try the same with guitar plugged into FX return, still buzz?


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## Verne (Dec 29, 2018)

I think I figured it out. Silly me. I've been trying out the 18w and 36w settings and this is when I really noticed the buzzing. After taking the cover off and moving all the tubes around and making sure they were all seated nicely, the buzz is still there, but all the glowing looks normal. The 2 power tubes that looked like they weren't glowing as brightly, is because the top part inside is different and I could see the bright glow on the backside once opened up. They are Sovtek, but different numbers on them. All EL84, but 2 each of 1305 and 1201. I am going to play it for a bit more and see if I am just being too perfectionist with the sound it makes. I will put new tubes in it all around just so I know that they are all the same, and all installed at the same time. Thanks for the help, but my ears may get the better of me. I blame that on being a trombonist since Gr6 (back in 197x)


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