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Post by gtrplaya87 on Nov 7, 2007 10:55:08 GMT -7
hey, got a new 66(sounds awesome) but i have to replace power tubes. i called and told dr.z about the problem and hes sending me more.
i heard something about "leathal voltages". does that pertain to me just putting new tubes in?
also, how often should i change the tubes in my amp for the best tone? i play around 3 times a week.
thanks
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Post by iggs on Nov 7, 2007 11:24:37 GMT -7
Hey man,
congrats on the amp ... yeah it does sound awesome fo' sho'!
"Lethal voltages" pertains to touching live wires inside the amp when it's turned on. The capacitors (big blue can looking things) can also store and hold charge long after the amp has been turned off and can discharge through your body if you happen to touch anything connected to them ... NOT GOOD! DC voltage and current is particularly nasty because your muscles contract and you are unable to let go if you grab something.
You can just put new tubes in and you will be OK. However, your amp will likely still need biasing and sounds like you might want somebody else to take a look at it. It should be a minimal bench charge at any respectable amp shop so I would suggest taking the amp with the new set of tubes and get it biased.
Your ears are the best judge when deciding when to replace tubes. It depends not only on the frequency of playing but how loud you crank it, if you attenuate it or not and how hot or cold your amp is biased. If the amp looses power, punch, is distorting in an unpleasing matter or is just starting to sound flat, you may want to look into a new set of tubes.
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Post by kledbet on Nov 7, 2007 11:32:43 GMT -7
With most KT66 tubes made today you are probably good for around 3000 hours :-) As long as you keep the bias around 34-36
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Post by gtrplaya87 on Nov 7, 2007 11:45:58 GMT -7
thanks..the dude (at dr.z) said i wouldnt have to bias it if i got the same groove tube with the same rating #. but if i need to bias it i will.
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Post by iggs on Nov 7, 2007 11:48:21 GMT -7
thanks..the dude (at dr.z) said i wouldnt have to bias it if i got the same groove tube with the same rating #. but if i need to bias it i will. Yeah, the GT tubes with the same rating will be within a "range" and close enough so you don't have to bias, I always like checking it regardless ... it's the OCD kicking in and I don't mean the Fulltone OD pedal ...
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Post by dixiechicken on Nov 7, 2007 13:42:32 GMT -7
DC here!
Just replacing the power tubes is a piece of cake - IF - you just take it easy. ( re-biasing is more convoluted - if not terribly terribly difficult - with proper tools )
The hardest part is loosing the 4 screws att the bottom of the head - and then gently pulling the chassies out - and later pushing the chassies back in - without damaging the new tubes. Don't sweat it, don't hurry it, don't force things too much and you'll be OK.
Before doing this just "DRAIN" the amp before opening it. Then you don't have to worry about lethal voltages.
DRAINING THE AMP: 1) Turn on the amp - just like you normally do. 2) Let i warm up - just like always. 3) Turn on the standby 4) Plugin the guitar and play for a 30 seconds or what ever. 5) Without doing ANYTHING ELSE - pull the power cord OUT of the wall socket. 6) When the amp is totally quiet - and all lights are dead - and the tubes have cooled down a bit. Then it's time to start dismantling the head - the amp IS DRAINED.
Just to play it safe - put on a pair of leather gloves when it's time to push the chassies out of the head-cab.
Cheers: Dixiechicken!
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Post by kledbet on Nov 7, 2007 17:43:10 GMT -7
Great point DC on just pulling out the plug to drain the caps!!!
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Post by LeftyLang on Nov 7, 2007 21:53:40 GMT -7
thanks..the dude (at dr.z) said i wouldnt have to bias it if i got the same groove tube with the same rating #. but if i need to bias it i will. Yes that is true as long as the last person biased the amp properly (if it is the 3rd set of tubes). If it has the original set from the Doc you will be fine.
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Post by dixiechicken on Nov 8, 2007 4:01:53 GMT -7
BTW - when you remove the KT66 power tubes. Try to gently and firmly remove the tubes - by pulling them straight out of the socket.
Try to avoid prying them back and forth - that will VERY easily break the center guiding post on the tubes. ( it did on one of my original GT KT66 )
The tube will still work JUST FINE - long as the glass-bottle is intact. ( as is mine ) You then just have to be VERY VERY careful to align the tube up properly with the holes in the socket - Pin 3 to hole three in the socket etc.
Myles knows about a "Antique Electronic" - something - that actually have repair kits for this - ask him.
Cheers: Dixiechicken!
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Post by zdogma on Nov 8, 2007 6:00:25 GMT -7
BTW - when you remove the KT66 power tubes. Try to gently and firmly remove the tubes - by pulling them straight out of the socket. Try to avoid prying them back and forth - that will VERY easily break the center guiding post on the tubes. ( it did on one of my original GT KT66 ) The tube will still work JUST FINE - long as the glass-bottle is intact. ( as is mine ) You then just have to be VERY VERY careful to align the tube up properly with the holes in the socket - Pin 3 to hole three in the socket etc. Myles knows about a "Antique Electronic" - something - that actually have repair kits for this - ask him. Cheers: Dixiechicken! Good advice, I've broken off one of those locator pins, too. The base is pretty thin. Its a big problem on newer amps when the sockets are still quite tight.
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Post by dixiechicken on Nov 8, 2007 8:55:46 GMT -7
Yes and I mentioned this - at some other place on this board.
My original Groove Tubes KT66 tubes were a much tighter fit in the tube sockets - compared with the NOS G.E.C KT66 I have put there now.
GT KT66 was as tight I felt the spring retainers were more of a precaution then actually needed. But with the G.E.C KT66 - I would definitely NOT want to be without the retainers.
Cheers: Dixiechicken!
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Post by gtrplaya87 on Nov 8, 2007 14:22:52 GMT -7
cool, thanks alot guys.
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