alright i will apologize in advance for being mostly in the dark here. i recently acquired a really beat up bassman 100... the housing of the output transformer is cracked and just hanging there... no tolex... etc. but it powers up and works (the sound is pretty lacking, i assume the tubes should be replaced). i've been drumming in bands for a few years now and after seeing guitar player after guitar player all with different ideas of how to treat tube amps and all with mounting repair bills, i can't stand not knowing just how they work. and since it was free, i figure fixing up the bassman might be a good place to start.

so can anyone suggest any books i would want to read? maybe old radio engineering textbooks or something? do any guides exist specific to my task? i guess i would wanna start with things like biasing new tubes, cleaning the pots, avoiding being electrocuted, right? any help is appreciated.

It is good to aquire information on tube amps. Tube biasing takes specialized testing equipment to do properly.

Fixing the transformer is possible you can buy replacement tranformers but you risk getting shocked by the capacitors which in a guitar amp that size could give you a leathal shock. I would highly recommend that you take the amp to a professional repairman.

I have done reading about tube circuts and amps and built some projects but would not recomend diveing in on a amp that big as your first project. There is a lot of information on the web though which is more guitar amp specific (guitar amps tend to be larger and more heavy duty than older radio circuts which is what I look at). I would start out with some of the smaller projects you can buy online to learn about amp theory and take the slow road on aquireing electronics knoledge.

Take the amp to a repair man perhaps he will let you watch as he makes the repairs if he knows that you are interested in this type of thing. Like when Evel Kinevel would jump cars on his motercycle he would recommend you leave some things to the professionals and not do it at home.

If you can understand fairly techy writing, I cannot recommend Kevin O'Connor's "The Ultimate Tone" highly enough. GREAT book.

My first amp project was a Traynor YBA-1A, which is not *terribly* far off from a Bassman. It's easier to work on, with it being a handwired point-to-point amp and all, but as far as the actual circuits, they're very similar.

Replacing the output transformer will be just about as easy an undertaking as you're gonna get. It's pretty much going to involve buying a new transformer, desoldering the one in there now, unscrewing and removing it, screwing in the new one, and soldering the new one's wires in place. It's not very complex, as far as working on a tube amp goes.

The O'Connor book is awesome. I cannot recommend it enough.

I've got a Mullard manual from the 50's. It is an excellent reference for understanding valve (tube to you) amps and also contains complete schematics and plans for several different amps. I've often thought about scanning it and putting it online in the EA gmail account.

Is anyone interested? It'd take a while to do, so I'm not going to if there's no point.

Let me know.

Nico Adie wrote:I've got a Mullard manual from the 50's. It is an excellent reference for understanding valve (tube to you) amps and also contains complete schematics and plans for several different amps. I've often thought about scanning it and putting it online in the EA gmail account.

Is anyone interested? It'd take a while to do, so I'm not going to if there's no point.

Let me know.

I would absolutely like to see this! I also found an RCA Receiving Tube Handbook online this past weekend, which is a great and probably similar read.

I always wondered why y'all call them valves, when if you consider something like a rectifier tube, there is nothing valvelike about it... sure triodes, tetrodes, pentodes etc have a "valve-like" function what with the control grid... but what about a rectifier tube? Nothing remotely valve-y about it! Ha!

the RCA tube manual, available at a university library near you.

RCA tube handbook, available in pdf format on Harvard's website!

http://www.nmr.mgh.harvard.edu/~reese/RC10/

This is an older version, so it doesn't have some tubes (cause they weren't invented when this version came out) but it's a great place to start if you wanna learn some stuff about tubes in general...