It's not online, but you can easily get The Tube Amp Book by Aspen 
Pittman at Amazon or similar. It's kind of expensive but it totally 
will bring out the geek in even the most casual guitarist. It'll tell 
you the difference between point-to-point wired amps vs. hand wired, 
what recifitiers do and why they are often a solid-state component of 
an other wise "all-tube" amp and most importantly why certain amps 
sound the way they do.

Some tube amps suggestions:
If you have very little money to drop on a Carr, Dr. Z., Matchless, 
etc. try finding a used Sovtek on eBay. I have a Sovtek bass head 
that rocks nuts and I have owned a MiG60 and a MiG60. All great. Clay 
has a Tube Midget and it really smokes too.

Gibson Goldtone amps are really great. Some of the new Orange's are swell.

Remember, the number of knobs on an amp is inversely proportional to 
how good it is!

I play a Carr El Moto which is based on the circuit in an old Matamp 
from the early 60's. 55 watts of warm but brittle TONE.

Mike
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