Learning amp repair

JimmyM · #1 03-03-2009, 05:57 PM

I find myself getting more and more fascinated by the inner workings of amps and electronics, and now I'm interested in learning about amp design and repair. Ideally I'd like to learn enough to be able to do amp repairs since you never see an amp repair shop around here that isn't swamped. The only problem with this is that I haven't the faintest idea except on the most basic levels of how amps work, and no idea on how to pursue it in a serious manner.

So what would be the first couple steps I should take here? I really don't learn well out of working from books on my own, but I learn pretty well when people show me the concepts, so I'm thinking maybe I'd take some classes at a tech college or something. If anyone could point me in the direction of learning how to do it at a professional level, I would appreciate it.

projectMalamute · #2 03-03-2009, 06:02 PM

I started here:

http://ocw.mit.edu/OcwWeb/Electrical...Home/index.htm

They have the complete videos of every lecture for a bunch of classes up on line.

blmeier7 · #3 03-03-2009, 06:10 PM

I've also been interested in the amp workings and electronics in general. This is a pretty nice site! Thanks!

B-string · #4 03-03-2009, 06:13 PM

The internet is a wonderful thing. I had to learn the old way, Radio/TV repair shop and lots of classrooms.

anderbass · #5 03-03-2009, 06:21 PM

Quote:

Originally Posted by JimmyM

I really don't learn well out of working from books on my own, but I learn pretty well when people show me the concepts

Me too...

If you had the time, I'd consider talking the best amp tech in town into letting you volunteer your services as a part time apprentice. You'd probably end up fetching coffee, sweeping floors and chasing down parts but you'd also be picking up a wealth of info by simply watching him work.

(good to see-ya back man)

BigOldHarry · #6 03-03-2009, 06:22 PM

don't be afraid to get some books too - start with the old basic books on voltage/current/impedance and all that stuff. Start with the *basics*.

Interceptor · #7 03-03-2009, 07:58 PM

Pick up a copy of the ARRL Handbook. Try and find one from the late 60's to early 70's. Great resource on how things really work. Also, pick up an old RCA tube manual.

I'd recommend pairing up with an old ham with good tech skills. Some of those guys are the best tube amp fixers on the planet!

MIJ-VI · #8 03-03-2009, 08:05 PM

Quote:

Originally Posted by anderbass

Me too...

If you had the time, I'd consider talking the best amp tech in town into letting you volunteer your services as a part time apprentice. You'd probably end up fetching coffee, sweeping floors and chasing down parts but you'd also be picking up a wealth of info by simply watching him work.

(good to see-ya back man)

+1. Being at the elbow of one who is where you want to be is a useful approach--and fun too!

Watching a buddy (a non-musician, yet excellent electrician, carpenter, plumber & all-round problem-solver) build a pedal board for me years ago (I bought the pedals, parts, and beer) allowed me to observe the logic/common sense he used in analyzing a task into its constituent components, and then tackling each one as a sub-system.

This enlightening perspective enabled me to expand my technical competence from changing a few tubes in an SVT, to teaching myself about refurbishing two hardware, and configuring three software platforms. I now know as much about computers as yer average eight year old.

Learning a little 'roadside maintenance' is good for a musician to do. As many of the threads on this, and other boards will testify, ours is an often overwhelming world the moment we plug in...

Projectile · #9 03-03-2009, 08:11 PM

Quote:

Originally Posted by projectMalamute

I started here:

http://ocw.mit.edu/OcwWeb/Electrical...Home/index.htm

They have the complete videos of every lecture for a bunch of classes up on line.

Holy crap that link is awesome! Major props for posting this!

Bassmec · #10 03-03-2009, 08:38 PM

Quote:

Originally Posted by Interceptor

Pick up a copy of the ARRL Handbook. Try and find one from the late 60's to early 70's. Great resource on how things really work. Also, pick up an old RCA tube manual.

I'd recommend pairing up with an old ham with good tech skills. Some of those guys are the best tube amp fixers on the planet!

Love the RCA Books they are beautiful.
Just get a small project pedal kit and build it, Valve overdrive is bags of fun for not much outlay to start with. Warning! this is highly addictive.
Just finished whacking a Mercury fatstack TM! OP transformer and add on choke kit to an oldish Marshall JCM 900. OH and a nice warm quad of well matched Mullard EL34's its already got a nice fruity set of pre amp tubes. Sitting steady at -37.7 quiescent on the old bias probes.
It sounds fecking glorious power soaked via a motherload into this old fender CTS 12" Square magnet speaker in an old Traynor open back cab. This is the down side, its not mine! I just get paid a pittance for the all the love I put in.

vin*tone · #11 03-03-2009, 09:14 PM

Jimmy- Build yourself a Flipster.
http://www.runoffgroove.com/flipster.html
Its great way to learn basic soldering/electronics while learning about the circuit topology of the B15 pre.
You can get a kit from OLC or round up the parts yourself.

JimmyM · #12 03-04-2009, 09:04 AM

Thank you guys for the advice. I hope to go over some of it later today.

Bump for the day crowd.

BassmanPaul · #13 03-04-2009, 10:30 AM

Jimmy, there are a plethora of books available on tube amp repair. Some good and some even gooderer.

Reading them will give you an idea of what's going on but you should try building something. Your beloved B15 is a really simple circuit and could be built fairly cheaply. As always it's the iron that costs the most but Hammond have transformers that will fit the bill.

Books, check out Old Colony, Antique Electronics Parts Express on the like for titles.

You will also need test equipment. Digital multimeter or three, Audio signal generator, Scope, dummy loads, tube tester the list goes on but those are the main ones. The book I liked most was written by Jack Darr and contains a lot of good solid information. It has been reissued by Old Colony I think.

Just remember don't touch nuttin' "hot"!

Paul

Passinwind · #14 03-04-2009, 10:40 AM

Quote:

Originally Posted by JimmyM

So what would be the first couple steps I should take here? I really don't learn well out of working from books on my own, but I learn pretty well when people show me the concepts, so I'm thinking maybe I'd take some classes at a tech college or something. If anyone could point me in the direction of learning how to do it at a professional level, I would appreciate it.

Plenty of community colleges offer basic AC and DC circuit theory. Sounds like you need to find one with a good lab class and an instructor with good audio electronics chops though. I lucked out in trade school and got two teachers who owned a recording studio and talked about audio applications at every opportunity.

I've trained a few techs myself over the years. In return, these guys answered the phone for me and generally made themselves useful so I could do the actual work a bit more of the time. You might shoot for a relationship like that yourself, eh?

gerryjazzman · #15 03-04-2009, 11:41 AM

Jimmy, you can also take a look at Pete Millet's technical books website:

http://www.pmillett.com/technical_books_online.htm

Pete's been going ape over the past few years scanning in a lot of old out of print books on electronics, much of it based on vacuum tube technology and making them available as free PDFs just because he's a nice guy. Of particular interest is the Radiotron designer's handbook, and even a couple of old ARRL Amateur Radio Handbooks (and a S***load more). Of course there are a lot of newer resources as well as some others mentioned, but there's a LOT of interesting stuff here and it's free.

If you want to look at something that's geared directly at musical instrument amps (tube-based guitar and bass), take a look at the London Power's The Ultimate Tone (TUT) series by Kevin O'Connor:

http://www.londonpower.com/

It can get pricey if you buy several of his books but there is a lot of repetition so it's not really necessary. Some are theory based (not hardcore like the classic texts, but practical theory), some are project based (how 'bout building a fliptop clone, or SVT kind'a clone, or a clone of a Marshall, Vox, or Traynor Bass Master or Custom Special? Check out TUT3). I know there are some that disagree with some of Kevin's opinions, but his books are still interesting reading and have some valuable info in them.

OrionManMatt · #16 03-04-2009, 11:54 AM

Wow @ the Pete Millett link.

beans-on-toast · #17 03-04-2009, 12:31 PM

I think that the best way to start, is to watch and learn from others and then at some point, dive in. Eventually, you will need to study electronics theory, but you can learn a lot of practical things before
getting to that point. Just like learning an instrument and then learning to read.

If you are interested in designing, building, and repairing amps, this is a good place to start (http://www.el34world.com/Forum/index.php?board=13.0).
There are many other sites concentrating on different types of amps: pedals, studio equipment, hi-fi, etc. depending on where your interests lay.

From a practical point of view, the first thing you need to do is learn how to solder. Buy a good soldering iron with an adjustable heat controller and some soldering tools. Something like this http://www.cooperhandtools.com/brand...c=037103191311 There are soldering tutorials on the net or you can buy "learn to solder kits" that include desolding braid, a desoldering pump, solder and an instructional DVD like this one (http://cgi.ebay.com/LEARN-TO-SOLDER-...#ht_717wt_1167).

One approach is to study proven designs and trying to understand them. Here is a good source for many of the classic amp schematics http://www.schematicheaven.com/index_HTML.htm. Building and modifying amps is a great way to learn. A pedal kit is good place to start. You get to learn how to solder, how to modify, and you aren't exposing yourself to lethal voltages. Transistor theory is based on tube theory. The designs can be very similar, as in the Flipster.

If you are more ambitious, there are many amp kits available. Weber offers many interesting kits (https://taweber.powweb.com/store/kits.htm). Unfortunately, these kits don't come with any documentation suitable for a beginner. Mission amps (http://www.missionamps.com/kits.shtml) offers an excellent 5E3 (Fender Deluxe) kit that includes step by step assembly instructions and technical support. Metramp (http://metroamp.com/) offers nice Marshall kits. Again good support. If you want to build a tube amp kit with an instructor in a classroom, there are seminars offered such as this one (http://www.specimenproducts.com/guit...p_weekend.html).

All this can be very expensive. To keep costs down, you can buy old amps and referbish them and resell them. Old junkers can be found and stripped and the parts such as the chassis, transformers, and tube sockets can be reused to build whatever amp you have in mind. One excellent platform for building an amp upon is test equipment. I've bought equipment like Hewlett-Packard Model 200CD oscillators (http://bama.edebris.com/manuals/hp/200cd/) at hamfests (ham radio fleamarkets http://www.arrl.org/hamfests.html)
for $15-25. Almost all the parts are there to build an amp. And they are top notch parts. All you need to do strip some of the parts, rewire it and add an output transformer. This approach is a fantastic educational tool.

As for the books on theory, check out these classics: Radiotron Designers Handbook 4th edition by Langford-Smith, Electric Guitar Amplifier Handbook by Jack Darr, The RCA Radiotron Manual RC10. These and many others are available here (http://www.pmillett.com/technical_books_online.htm) or reprints from Antique Electronics (http://www.tubesandmore.com/ ). The Fender Bassman (5F6A) is analysed in detail in this book ( http://www.pentodepress.com/contents.html and http://www.pentodepress.com/tubes/va...rcheology.html). There is also a series of tutorials by Kevin O'Connor that are very good ( http://www.londonpower.com/tube-amp-books.htm ) as has been mentioned.

David

JimmyM · #18 03-04-2009, 01:35 PM

Wow, thank you guys for such detailed info! As soon as I get a little grub, I've got a lot of surfing to do!

Kindness · #19 03-04-2009, 01:37 PM

Quote:

Originally Posted by beans-on-toast

If you want to build a tube amp kit with an instructor in a classroom, there are seminars offered such as this one (http://www.specimenproducts.com/guit...p_weekend.html).

I like all of your other suggestions, but having gotten my start at this "school," I'd highly recommend other alternatives.

JimmyM · #20 03-05-2009, 09:25 PM

Hey thank you guys again for posting all this info. I'm starting with Malamute's link but I've done a little grazing on the other stuff as well. I'm really amazed you can get whole series of lectures for college classes online for free. Lot of stuff to digest. A little tough to figure out where to start, but I don't seem to be struggling too much with the beginner concepts. That's a good sign!