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Tube amp service.

Discussion in 'Amps and Cabs [BG]' started by 68Goldfish, Feb 17, 2008.


  1. 68Goldfish

    68Goldfish Supporting Member

    Nov 4, 2006
    Port Orchard WA
    Hey dudes. I'm wondering how one goes about learning how to service tube amps. I mean from the ground up. I'm an auto tech (have been for twenty plus years) so I'm mechanicaly inclined and have a lot of electrical background and I've got all the tools I think I would need. . I know I could fix these amps if I had the proper information and service manuals. Is there a good book somebody could recomend on the theory, principles and repair of tube amps? I understand there's significant voltage differences between automotive and house aplications but I think I could do it safely.
    Thanks TB:bassist:
     
  2. You could start by taking an electronics course. There are home study companies who offer service technician training. these will tell you nothing about tube amps but will teach you how to diagnose and repair SS equipment. This training will help you when you work on tubes. To learn about actual tube electronics, build something simple. A pre-amp or a single ended amplifier perhaps. I will take time to gain the knowledge you need just as it took time to learn about auto mechanics. As you gain experience maybe build a 50 or 100W amp. Buy old tube equipment and restore it.

    As for books, several tube "Gurus" have written books which explain how tube stuff operates and some have schematics for existing equipment. Dave Funks' Tube Amp workbook is one example. Jack Darrs tube amp book is very good. Kevin o'Conner of London Power has several books available. All are quite well written.

    The biggie here is to remember at all times that a tube operates a lethal voltages. Be very aware at all times of what you are about to touch.

    P.S. I can't remember ever seeing an actual service manual for a tube amp. They may exist but mostly you will be very lucky if you can even find the schematic for the amp you are working on.

    Hope this helps

    Paul
     
  3. Jazzman

    Jazzman

    Nov 26, 2002
    Raleigh, NC
  4. Stromrider

    Stromrider

    Feb 16, 2008
    CT, USA
    Check out some other forums... diyaudio.com has a good tube section. Google is also your friend.
     
  5. Warpeg

    Warpeg Supporting Member

    Jun 20, 2005
    Ohio
    I can tell you some of the equipment that you'll need. My workbench has an O-scope; a 1000w load/test bank; a sine/square wave generator; a good multimeter (probe and alligator leads); adjustable voltage soldering gun; assortment of basic tools (screw drivers, ratchets, etc.), assortment of resistors (1/8, 1/4, 1/2, 1, 2, watt), caps (several kinds), diodes, pots (linear and audio, trimmer, etc.), and other basic electronic components; assortment of common tubes (12AX7A/B, 12AU7, 6L6, 6V6, 6550, EL34, EL84, etc.); etc. There are a ton more items that you'll need, but this will give you a start. You'll have several thousands of dollars in a decent setup. The rewards are endless, though!
     
  6. 68Goldfish

    68Goldfish Supporting Member

    Nov 4, 2006
    Port Orchard WA
    Thanks for the info guys.

    Being an auto tech all my life I'm definetelly no stranger to spending money on tools and the like. :)
     
  7. JGR

    JGR The "G" is for Gustav Supporting Member Commercial User

    Jun 29, 2006
    Maryland
    President, CEO, CFO, CIO, Chief Engineer, Technician, Janitor - Reiner Amplification
    i've learned to design and build from scratch over the years so you can certainly learn to service them!

    www.firebottle.com/ampage is the forum where all the techies hang out.

    www.tubesandmore.com (antique electronics) has a lot of books on tube amps. i have most of them and i think the ones by Kevin O'Connor are the best. start with TUT 1 and TUT 2. Dave Funk also has one you can get from there.


    JR
     
  8. mattvon

    mattvon

    Jan 22, 2006
    Minneapolis, MN
    This is almost precisely what I ended up with when I began the same process. I added an isolation transformer and a variac, but you can sure get away without these for a while.
    I can also recommend getting the best quality tools you can afford--but, as a mechanic, you already know this.

    The best way to learn is to find an experienced tech who's willing to share, but that may be difficult.

    Otherwise, I've found a number of books helpful:

    Aspen Pittman's "The Tube Amp Book" is great, if only for the huge collection of schematics. Many of these can be found on the Internet, but it's really nice to have them at your fingertips.
    Dave Hunter's "The Guitar Amp Handbook" is a great place to start learning how different components affect tone. Best conceptual book for beginners I've found.
    Though it's a bit older, Tom Mitchell's "How to Service Your Own Tube Amp" was the best "how-to" book I found. It's full of good, basic information.
    Readily available are .pdf's of the RCA Receiving Manuals. Get the most current one you can find--#27 or #30 would be great.

    Note that virtually NONE of these books specifically address bass amps--unless you count the Fender Bassman as one! :meh:

    Good luck in your quest--go slow, ask lots of questions, but most importantly--be CAREFUL. I'm a relative newbie, so I spend more time checking voltages with one hand than anything else.
     

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