new tubes, suggestions needed

B

bradthefattest

New member
as some of you saw i am sure, i have a problem with a crate vintage club tube amp, i am going to go ahead and retube it, see if that is the problem, and it cant hurt. it has 4 12ax7 tubes, and 4 el84 tubes. this guitar is used for folk, blue, and a little rock. just was wondering any suggestions for tubes to put in it, brand, or models or whatever. i looked on eurotubes.com, it had a little info. i dont know a whole lot about tube amps. thanks for any advice.
 
If you don't even know if the tubes are the problem, I would just get the Groove Tubes at GC rather than spending money on stuff you might not even need...yet...
 
i think most people will suggest jj's and i think that's what eurotubes sells? i've got friends that swear by them. next time i retube, i'm gonna check them out.

there's nothing wrong with going with groovetubes though. that's what i'm using currently. you just have to keep in mind that they only actually manufacture one tube(a 6l6) so except for that one tube, you're buying the same tubes every other tube company sells. i think groovetubes is popular because people trust them to match and test the tubes better than other companies, not because they actually carry higher quality tubes...........i dont know how true that assumption is though.

edit: they actually either do manufacture now or are going to manufacture a 6ca7 also.
 
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If you get the 12ax7's all in the same brand it'll be fine. They don't have to be "matched". The power tubes will be "matched" if you buy them together,
but usually they will be paired in twos. Although they are closely matched, the two pairs will be slightly off. Put one pair in the outer sockets and the other pair in the inner sockets. It sounds to me like you have a power tube that's going bad. I had a similar condition once.
Also, the preamp tube the farthest from the power tubes is the first gain stage,and is most suseptible to noise and hum. Try tapping on this tube with your fingernail. while it's acting up(without playing through it.) The tapping will be heard through the amp but any other noise, such as squealing or crackling is a sign of a bad tube. You can do this test on all the other tubes as well.
 
you can buy matched quads at eurotubes, so i am going to order those. do i need to get the amp rebiased after i put in the amp, or would that just sound better. wha i will do as long as it doesnt hurt anything, is put in the new tubes, and check all the solder points, see if any are burnt or cold solder points on the circuit board fix any problems. and then try it out. if all goes well. i will then get it rebiased(not going to try that yet. probably will get one of thos bias pulse things, or whatever, and also watch the guy that does it for me, i know someone that can do it, he is certified for something having to do with tube amps, he is a friend of a friend.
 
another quick question while we are on the subject of tubes, dont want to put a new post for it. My brother bought a mesa boogie dual rectifier solo head new last year. how often should he retube it, and also how mcuh would it cost to get rebiased, because i have read that it should be done when you buy it because they biased cold, and sound a lot better rebiased.
 
Just gotta tell ya, Brad, that I think you're going about this all wrong. New tubes are unlikely to solve your problem, and then you're going to have an amp with new tubes, be down hunderds of dollars, and it still won't work.


Just my opinion from having been down this road and through this kind of shit many times before. First fix the problem, then replace the tubes if it's necessary or if you just want to.

Konanian said:
Try warming up some solder joints especially the ones on the pots that are board and chassis mounted. From time to time these things get metal fatigue and break thus becoming intermitent.
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This is a great suggestion - try this before you do anything else. It's easy and free, and makes sense.
 
ok sorry, i was going to do the resoldering before i retube it, hopefully that will fix it. but also i know that retubing this amp would help even once it is fixed. my friend has owned it for 2 and a half years now and hasnt retubed it, the guy it bought it from must have retubed it at some point, it has groove tubes in it. but it still needs retubing. and retubing it would only cost $30 for 4 new 12ax7, and $30 for 4 matched el84 tubes. but i will first try resoldering points on the board that look bad. and get back to yall today at some point with the results. i am recording a band from 2:30 til probably 6:00 or so. so it will be after that sometime.
 
Oh, I didn't realise the tubes were that cheap - go for it, then.

From the other thread, as far as draining the filter caps, you're probably OK if it's been off for a day - the charge has likely leaked off. But drain them anyway.

The filter caps are probably the largest ones in the amp. You should clip an alligator lead onto a several hundred ohm resistor (several watt size if possible) with the other end clipped to chassis ground. Then touch the open lead of the resistor to each capacitor lead for a few seconds.
 
What are these? i dont like how they are attached together so crappily.
 

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bradthefattest said:
cant i just hook a multimeter to it and see if it still has any voltage?
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Sure, but you still have to be able to discharge the capacitor(s) if there is much voltage (like more than 20 - 30v) present.
 
bradthefattest said:
What are these? i dont like how they are attached together so crappily.
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Those are two power resistors that someone has jury-rigged in there in series (probably to replace a single one of higher value.) Looks like there might have been problems with this amp in the past.:)
 
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