i recently bought an ancient motorola tube amplifier from a pawn shop. it sounds amazing but the tubes look a bit...aged...to say the least. i want to replace them, but i only recognize the 6eu7 pre-amp tube. the other 2 are a complete mystery to me; 6b05 and 5y3. are these just old names for more common tubes? or am i looking for some pricey vintage items?
-JustiN-
I don't want you to play me a riff that's going to impress Joe Satriani; give me a riff that makes a kid want to go out and buy a guitar and learn to play.
— Ozzy Osbourne
6b05/EL84 Are one in the same multiple beam-power-tube. The real old version is the one you have. Then it progressed to EL41, ECL86. 6BQ5 is the U.S. name for the tube. Famous in the Vox AC30, and one of the favorite tubes of modern boutique amp designers, like Mesa Boogie, Carvin, Peavey, Torres, and many others. I use a power amp that has 8 EL84's as a pre-amp then drive it into a Dummyload.
5y3 is a Rectifier tube. These tubes are the heart and foundation of your amplifier's power supply. Poor rectification can adversely affect performance or severely shorten the life of your amp.
Joe
cool, this replacement is going to be easier than i planned! :D
with the 6eu7, could i use a 12ax7 instead?
wow, 8 el84's! that must sound sweet cranked!
I don't want you to play me a riff that's going to impress Joe Satriani; give me a riff that makes a kid want to go out and buy a guitar and learn to play.
— Ozzy Osbourne
That's 6BQ5 that the EL84 substitutes for.
The 5Y3GT is a popular rectifier tube, and Sovtek sells a modern substitute.
Here's info on the 6EU7: http://www.nj7p.org/Tube1.php?tube=6EU7
I don't think a 12AX7 will sub without some socket rewiring.
BTW, I wouldn't ever change tubes because "they look aged." I've got 1930s radios still working fine with some of the original tubes in them. "Preamp" tubes last a long time. "Power" tubes and rectifiers wear out a lot faster. A lot of the tubes I use in old equipment are "pulls," used tubes pulled out of scrapped gear. They generally work just fine. The time to change a tube is when it's no longer working right.
"A cheerful heart is good medicine."
The 6EU7 have a different pinout. As suggested you'll need to rewire. They will sound pretty close to a 12ax7.
Joe
There are zillions of online tube dealers that'll have out-of-production tubes like the 6EA7. First place I'd look: Antique Electronic Supply
"A cheerful heart is good medicine."
ok, maybe "aged" wasn't the best word for me to use. "abused" would fit better. one of the el84's is cracked and the 5y3 has plier marks on it. yes plier marks lol i wanted to replace them all so both channels worked and i could finally hear this thing at full volume!
anyways, i was looking on musician's friend for the tubes and i found that:
1) they carry the 5y3 and the el84's
2) you can order the el84's in all different "hardnesses". how does tube "hardness" affect the tone of the amp?
I don't want you to play me a riff that's going to impress Joe Satriani; give me a riff that makes a kid want to go out and buy a guitar and learn to play.
— Ozzy Osbourne
2) you can order the el84's in all different "hardnesses". how does tube "hardness" affect the tone of the amp?Unknowable. They're trying to make a virtue out of a vice, the variability of characteristics from one tube to another with substandard quality control in manufacturing, and sort what comes out of the factory into groups based on some unspecified tube characteristic. Supposedly the "softer" ones break up earlier than the "harder" ones, but you'd have to try them in your amp to know the real difference (if any.)
"A cheerful heart is good medicine."
For tubes, I would recommend a dedicated tube dealer like Bob at Eurotubes or The Tube Store, or the antique electronic supply. These people will be able to match the tubes you need to the amp and the sound you want. Bob was a great help to me in matching tubes to my Galaxie 10 to modify the sound in the direction I was thinking by sending me tubes that tested in the appropriate range. The tubes arrived in 2 days and when one tube was damaged in shipping he had a replacement to me in 2 days no charge no questions. He only carries JJ tubes so you might need to look elsewhere for some oddball tubes.
The JJ 6L6GC is a very musical tube. I'm not familiar with his EL tubes. I also like the ECC83S (12AX7) tube for a full, rich, preamp tube with lots of dinamics without the harshness and odd harmonics of some Sovtek tubes I've tried. The ECC803S is an interesting 12AX7 replacement if you really want to smooth out your sound, sounds sweet with my Tele (which had rough spikeyness with the Sovteks) but was a little too mellow for blues from my SG... Great for a warm humbucker crunch, though.
