Sloan wrote:What are the best Amplifier repair/modification books ever?
There's one dude in about a 50 mile radius that will work on a tube amp here. i need to learn this magic and start ripping people off.
I took myself through Tube Amp 101 by doing a ton of reading on the Web -- enough to know that for everybody who loves a particular book, there's somebody else around who'll dump on it. I could stand to read a couple books, but I haven't yet so I don't have an opinion on them. Tonight I'll go hunt up a few titles I've seen recommended here and there. Some of the others on the boards may have some suggestions in the meantime.
Billy3000 wrote:good idea. I've been wanting to replace the tubes in my Twin Reverb, but the only guy I can find that will do it is going to charge around $200 for it, since it's about $150 for all the tubes, and then it'll need to be biased and all that stuff.
Merely replacing the tubes in your Twin does not require re-biasing, and some Twins don't even provide a way to bias, short of dropping the chassis and messing with resistors inside. The point is that they're intended to be more or less plug-and-go with tubes, and you can do this yourself for well under $150, depending on shipping. For example, you can order a complete set of Twin tubes from eurotubes.com for $116 plus shipping. These are JJ brand tubes, which I've been very happy with. (That's not a plug for either eurotubes or JJ. Both have done fine by me, but there are other options too.)
Anyway, just follow the tube chart on your amp and plug each type of tube in where indicated, being careful to line up the keys/pins and not bend anything. If you don't have a chart, the order of tubes, starting with the big power tubes, goes:
6L6 6L6 6L6 6L6 12AT7 12AX7 7025 12AT7 7025 7025
Many people, including me, use 12AX7 tubes instead of 7025s. For Twins, they're interchangeable and just a matter of taste.
Rebiasing when changing tubes is a nice-to-have rather than a must-have, so there's no need for it to hold you up. In fact, it's probably best to play the new tubes for a few days before re-biasing, as their bias is likely to drift a bit as they get broken in.
