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Posted

i feel like i've been monopolizing this area the last few days but i'd like to ask another question and then i'll lay low for a while...at least until all the parts i've been ordering arrive.

when i want to learn something i usually buy every book i can find on the subject, read them, ask questions and then jump in. i've approached working on tube amps the same way. so far i've purchased two basic electronics books, a book titled, "how to test almost everything electronic", a very informative book by patrick mckeen called, "keep your gear running..electronics for musicians" and one titled, "how to service your own tube amp" by tom mitchell.

with those books and your help i've learned a lot in the 3 or 4 weeks since i started but some of the terminology and the actuall mechanical aspects of the amps still puzzle me. i can pretty well identify the components both in the amp and on the scematic. i generally understand their functions. but i need help tying them all together.

i understand the mechanics of biasing an amp but the two amps that i'm working on, the ampeg and the alamo are evidently biased by completely different methods.

the ampeg has a circuit board running it's entire length and it's difficult to trace the circuits. the alamo is open and everything is wired together with jumpers and everything grounded is grounded directly to the chasis.

anyway, i've just ordered "the tube amp book" hoping that it'll fill in some of the blanks. so my question is this, is the information that i need available in books or am i going to have to break down and take some classes? what reference books do you keep on your workbench? any videos available that you might recommend that will actually have a guy pointing to a rectifier tube so that i'll know where it is?

i guess that's more than one question but i promise i'll give someone else a chance after this...for a while. :D

Posted

I'm sure there are others here who know far more than I do (not hard to do anyway) but what I would recommend is starting to hang out on some amp boards, read every post you can, hang out there every day and stay current on the threads others have going on, and ask reeeeal nice like some questions here and there.

Amp guys are hard to get information out of, for the very same reason I have a hard time explaining how a guitar works from scratch, because usually I've already typed it out in detail many times before (they have) and usually the question asked, whether the inquisitor knows it or not, needs -far- more information discussed to properly answer the question than the inquisitor really comprehends. They would have to literally start from dead-scratch to REALLY explain it to you, and that takes a lot of time and typing. Some guys will do it, others are tired of doing it, they've been doing it for years on end.

I think it's something that you get steeped in with time, lots of time, just following lots of threads and poking around.

Well-versed amp guys (like I do) like specific questions, that tells them that you've done at least some homework on your own already, and they can tell by the questions you ask if you have or not, and it won't take them a whole page of typing to answer your question, they can get directly to the point at hand.

I've always wanted to get the Tons of Tone series by Kevin O' Conner, but I stay so busy with what I do already it's hard to find the time to commit to it.

A few good amp boards I know of and/or hang out on:

WeberVST bulletin board (amps section in particular, but all of them are good)

This one I highly recommend, lots of intelligent amp guys there, and lots of threads, and lots of information passed back and forth regularly. In other words, a 'high traffic' amp site, and pretty friendly too (although it has it's moments, amp guys can get awfully cranky sometimes)

Ampage

The Amp Workshop

That AX 84 thingee

TDPRI Amp section

There are also some good Yahoo! amp sites, those are e-mail groups, but there tons of them out there, and they get real specific, like you might find a group there specifically for Alamo amps and stuff like that.

I belong to the Traynor amps group, and I used to belong to the Magnatone groups site.

Those two sites are full of guys who are masters at working on those amps in particular.

There are a TON of other amp sites too, go to any of the sites I listed and there will be many links to other amp sites, some favoring Fender-style amps, some favoring Marshalls, etc...

Posted

Drak's pretty well covered everything, so I'll just add some personal notes.

  1. O'Connor's Tonnes of Tone and The Ultimate Tone series are expensive, but well worth having if you can afford them.
  2. The AX84 Forum is probably the most noob-friendly of the forums listed - Weber's board is friendly, but more builder oriented, and the guys at Ampage have been known to make noobs cry, so be prepared to be respectful and intelligent, or stay home.
  3. The P1 Theory Document at AX84 is a great place to start if you have trouble with what does what in tube circuits.
  4. Collecting and comparing schematics is a great way to learn about how the components iteract - for instance, the 5F6 Bassman and the original JTM45 are very similar, but sound very different because of key component changes.

Drak also brought up another point that can't be emphasised strongly enough - do your homework, and ask specific questions! A question like "Help, how do I bias EL34s?" is not likely to get positive responses, just like those "What paint do I use for a guitar?" posts over in the Finishing forum, but if you ask "I'm running a pair of fixed bias EL34s with 420 volts on the plates and 380 volts on the screens - what bias voltage should I be shooting for?", you're a lot more likely to get the help you need!

And if you find someplace that offers some kind of general tube electronics courses (not amp building - heck i can do that! I need to know how all this stuff works!), please let me know.

Posted

thanks again to you both...hopefully if my questions haven't been specific at times they've at least been intelligent. and i have literally started a new folder for all of the information and links that you guys have provided. they should keep me busy for a while. but i've got to keep crammin'. this is a small town with a ton of musicianst and word has already started spreading that i'm "working on tubes".

so i'll try a couple of the amp boards, lurk a while and then bug them with some questions while you guys get back to answering guitar questions.

Posted

well now i've got a headache from trying to remember all those guys. :D

i just cruised the ax84 site for a few minutes and i think i'll start there. a lot of guys seemed to have already asked the questions that i have..and so far i didn't see any blood or gore anywhere.

Posted

one of the best places that explains alot about the building blocks of tube circuits is http://www.aikenamps.com/

go to tech info and then have a look around. the stuff in introductory is the basics. theres a list of must have tube books, a list of commonlly used amp terms etc etc. its stuff that you may already know but its worth checking.

the advanced stuff is really ace. explains things like designing common-cathode triode amplifiers from the ground up and has a fair bit of info on biasing. unforunatelly there are still a few things i think it misses, like it doesnt have a very good description of the Load Line technique for biasing tubes IMHO.

however thats where i really started getting my good tube info.

otherwise tbh you just need to make sure you have a really good graso of electronics. tubes in truth are very simple beasts and IMHO people only think its tricky and voodoo because a) its old, :D it uses high voltages so its scary, c) some amp techs make it seem like you have to know everything to make a good amp

like everything else in electronics, get down the basic rules and a good understanding of how it all works and its simple

Posted

thanks johnnyg..i was saying pretty much the same thing to a buddy of mine..it's got to be easier to learn and then to troubleshoot and repair a tube amp than a solid state...i made the analogy the other day that i expect it to be like working on my 72 chevy versus my sister's 2005 whatever the devil it is.

i'll check that site out tonight.

Posted

yeah thats pretty much right. i have a couple of old bass amps that i got for free, both solid state. my god theres alot of crap on them. the power amp section has about the same number of parts as the bass man schematics ive seen and then there's the tone controls which while fairlly simple do take up a helluvalot of space.

man when i build amps theres gonna be 3 volume/gain knobs and 3 tone pots. thats all anybodies getting and i dont care about hissy fits

Posted

you must be from the south johhnyg..i don't think they throw hissy fits up north. :D

Posted

Im in the south in the UK yeah. which side of the pond were you refering to lol?

Posted

yep, that's exactly what i meant..(i'm going to quit before i get in trouble) :D

Posted

lol good point, you've got the info you needed. stop clogging this place up :D

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