#1
Hey guys, i just got my first tube head off of ebay. Its an Ampeg v-50h. It was working really well, but then it started rumbling a little but while i was playing at high gain, so i did my research and found that this was probably because of the pre amp tubes. So, i bough some new 12ax7 tubes and put them in. Well i put the new ones in turned on the amp (it has no stand by) and about 15-30 seconds of it warming up, it started making these crackling/popping noises (like it was before i put the new ones in). After a little while it decreased but i cant help but feel that the amp sounded slightly better before this problem occured. Could these popping noises be the new tubes breaking in or something, or just the amp warming up in general..or maybe the power tubes? Idk.

any help would be nice because im a little angry that the tubes are doing this since i sent 30 bucks on some new ones. could the new ones be bad?

thanks
#3
does it make the crackling noise all the time or just when your playing? and is the popping loud or just soft?
#4
Quote by Longshanks
Did you get it re-biased?



He only replaced the preamp tubes, which don't need biasing, for most all amps used in guitar applications.

I had popping too, but those came from my power tubes.
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#5
well the popping doenst really happen when im playing..when i first turn the amp on to let it warm up it pops pretty loudly, and more then once...along with crackling. It then fades away..but i feel the tone could possibly be better...

maybe it could be the power tubes. I really dont want to have to go get the amp rebiased though. especially since my band has a show next week
#6
the crackling could possibly a dirty pot?
My guess for the popping and crackling is that there is a shortage between a cathode and grid in an output tube.
#7
^^alright, so then i need new power tubes..... How important is re-biasing? Could i just buy the same brand if tube that are already in there? i dont really have time for this because really the only guitar tech i can think of would be the one at guitar center and their turnaround time sucks i believe. Plus im cheap!!

whats weird is the crackling seems to lessen as the amp warms up more?
#8
um if the amp was used off ebay which i'm assuming i recommend getting it serviced. i got my jcm 900 halfstack for 550 and it didnt' work at all. took it to get serviced they replaced all the tubes and checked it out made sure everythihng was working. only cost 50 bucks to service and then new power and preamp tubes. been working great ever since
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#9
Re-biasing is pretty important. The tubes have to be properly biased to let in the right amound of DC current. You dont need to re-bias preamp tubes, and you could probably get away with not re-biasing the power tubes if you are going to change them with the same tubes, since they should still be biased the same.

The crackling is probably a DC inbalance on the output stage, making a hum on the speaker stage then balancing out again. That's probably it goes away after.
#10
Quote by redrumsixsix6
Hey guys, i just got my first tube head off of ebay. Its an Ampeg v-50h. It was working really well, but then it started rumbling a little but while i was playing at high gain, so i did my research and found that this was probably because of the pre amp tubes. So, i bough some new 12ax7 tubes and put them in. Well i put the new ones in turned on the amp (it has no stand by) and about 15-30 seconds of it warming up, it started making these crackling/popping noises (like it was before i put the new ones in). After a little while it decreased but i cant help but feel that the amp sounded slightly better before this problem occured. Could these popping noises be the new tubes breaking in or something, or just the amp warming up in general..or maybe the power tubes? Idk.

any help would be nice because im a little angry that the tubes are doing this since i sent 30 bucks on some new ones. could the new ones be bad?

thanks
If you had the problem before, and have it still, obviously you need to look elsewhere for the problem. Output tubes (EL-34s) arcing internally? Carbon tracking on the circuit board or tube sockets (dries out after heating up)? Filter capacitors getting ready to explode?

Except for the output tubes themselves, you need to take this in for repairs. Do NOT go poking around in there. The voltages are high enough they CAN kill you.

Good luck,
SYK
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