#1
Just came across a Mesa/Boogie 5:50 212 combo in rough condition but a fantastic price. Didn't have a chance to play through it but I did power it on. The light comes on but there's a loud popping sound when taking it off standby and it hums, even on very low volume. The pop is however much quieter on 5w mode. One of the power tubes is also not lighting up. My first thought with the pop was a speaker problem, could it be both?

Is it just a power tube problem? If I was to plug in and play what would I expect to hear? I'm trying to gauge how much it would cost to fix it up.
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#3
Quote by Will Lane
I would get the proper matched set of power tubes for that model and switch them out. Never the less one of them is not lighting so most likely they need to be replaced.


Thanks for the quick reply! I'm just hoping it's the tubes and not a transformer problem or something
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#5
Quote by 311ZOSOVHJH
First step is to get some matched power tubes, extra fuses of all types for that amp, and at least 1 new preamp tube.


Why just the one (at least) preamp tube?
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#6
for testing

roll it through 1 slot at a time

if you have the cash feel free to buy all new preamp tubes but the chances of all of them being bad is very slim. I'd rather have 2 NOS preamp tubes then 4 crappy chinese preamp tubes.
#7
^Really if I was buying a used amp, one of the first things I would do is get new preamp and power tubes. Unless the ones the previous owner put in are recent and a brand/type I like.

Well, really any amp either used or new. New amps often have awful stock tubes. And it is good to have spares!

TS, I think Mesa has a color-coding system or something for their amps so you do not have to bias tubes. Just find out the info and get the right tubes and try them out.
Last edited by Will Lane at Dec 12, 2015,
#8
Quote by Will Lane
^Really if I was buying a used amp, one of the first things I would do is get new preamp and power tubes. Unless the ones the previous owner put in are recent and a brand/type I like.

Well, really any amp either used or new. New amps often have awful stock tubes. And it is good to have spares!

TS, I think Mesa has a color-coding system or something for their amps so you do not have to bias tubes. Just find out the info and get the right tubes and try them out.

Good points. Nothing wrong with that methodology. I only replace preamp tubes if I feel they need to be. For example, some of the Chinese tubes today are OK and I've had some decent Groove Tube pre's come my way as well. It just seems like a waste of money to arbitrarily buy new preamp tubes every time you get a new amp. See what's there, see if you like your tone, swap a good tube (like a known good JJ or JAN or Tung Sol) through and figure out the best combination.*

But yeah - if you get a used lower end amp or something that has original tubes then there is a good chance you will get all crappy chinese tubes so by all means, swap those out. Even higher end amps these days are coming with crappy tubes. Sometimes, like with Peavey or Mesa, you'll luck out and get all JJs

*some tubes have a cathode follower stage at maybe V2 and not all tubes work well in the PI slot so if that doesn't make any sense to you then ask first.

Also, no offense to the TS, but if you are buying a big heavy 5:50 in rough condition then I'm going to assume you may not have lots of cash laying around to buy all new tubes.
Last edited by 311ZOSOVHJH at Dec 12, 2015,
#9
Quote by 311ZOSOVHJH


Also, no offense to the TS, but if you are buying a big heavy 5:50 in rough condition then I'm going to assume you may not have lots of cash laying around to buy all new tubes.




Thanks for the help guys, really appreciate it

Ended up pulling the trigger, got it for $300. I plugged a guitar into it and was getting some sound, so I'm hoping the power tubes will fix it. Will definitely check out the preamp tubes while I'm at it though.
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