Should I retube my vintage Luxman amp?

[Asterix]

It's sound doesn't compare to my head amp in it's current configuration. Interestingly, using one of the stock Japanese 12AX7 tubes from the old amp yielded a similar sound in my MG Head. What I'm saying is the Japanese tube had a sound signature that I could hear in both amps when using the same tube, which leads me to believe, retubing the old Lux with some nicer tubes (at some point) would alter the sound quite a bit. It would be costly to use the best NOS tubes as this amp takes 4 EL34's and 7 12AX7's. Also, there is some sort of metal around 2 or 3 of the 12AX7's that seems to be glued on, and there is a wire running from it attached to the amp's circuit board (?) So I'll have to get around this if I plan to change all the tubes.
I might buy some cheaper tubes first to experiment to see how it affects the sound. Someone mentioned the Japanese EL34's in particular are excellent, so maybe it's not worth it to touch these tubes. I just imagine I'd prefer, say, Mullards in there, based on my experience with 12AX7's in my head amp. Maybe I could sell or trade these Japanese EL34's?

 

[Hirsch]

If you've got a vintage tube amp, it's going to need some work before going back into full use. Electrolytic caps have a lifespan of about fifteen or so years, more or less. A vintage tube amp is going to need to have those capacitors replaced, in order to perform well (as well as minimize the chance of a capacitor failure). There may be other parts that need replacement as well. You might want to find a site about vintage gear, or post in vintage gear asylum at Audio Asylum on how to restore the amp. They might also be able to give you a better idea of what you're going to have once the amp is restored. Once restored, the Luxman is likely to be a superb amp, but it's going to be a bit more than just changing tubes.

The metal cylinder around some of the tubes is RF shields around tubes that are amplifying very small signals, which makes them particularly vulnerable to interference. These are usually not glued on, but can come off with the proper twist. If spring-loaded, you may have to press down and twist. Rust may have locked them in place, though.

 

[Asterix]

Thanks. I got the tubes out with a little effort (not spring loaded)! Some vintage tubes in there

just a GE (could be a mullard? says britain) ECC85 and another Japanese 12ax7. About the caps... I'm not much of a DIY'er... can this repair be done without too much experience do you think? Also, how much might it cost for these parts? Finally, I noticed that it says '12AU7' next to one of the sockets where I got what I thought was a Mullard 12AX7 (could be a 12AU7?) Anyway, I don't have any 12AU7's now. I put a 12AX7 in there before and it seemed to work fine. Is this ok? Or should I get a 12AU7 for optimal performance? What's the difference?



Quote:

Originally Posted by Hirsch If you've got a vintage tube amp, it's going to need some work before going back into full use. Electrolytic caps have a lifespan of about fifteen or so years, more or less. A vintage tube amp is going to need to have those capacitors replaced, in order to perform well (as well as minimize the chance of a capacitor failure). There may be other parts that need replacement as well. You might want to find a site about vintage gear, or post in vintage gear asylum at Audio Asylum on how to restore the amp. They might also be able to give you a better idea of what you're going to have once the amp is restored. Once restored, the Luxman is likely to be a superb amp, but it's going to be a bit more than just changing tubes. The metal cylinder around some of the tubes is RF shields around tubes that are amplifying very small signals, which makes them particularly vulnerable to interference. These are usually not glued on, but can come off with the proper twist. If spring-loaded, you may have to press down and twist. Rust may have locked them in place, though.