Learning Tube Amp Repair/ Servicing

Discussion in 'Amps/Cabs Tech Corner: Amplifier, Cab & Speakers T' started by louderock, Feb 28, 2009.

  1. louderock

    louderock Supporting Member

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    I have a lot of amps and would love to know how to troubleshoot and repair them. I've done the BYOC pedal build and I change out pickups and pots in my guitars as well as bias my amps but that's as far as I've gone. So, I need to learn from step 1. What do you recommend? I found a dvd by Gerald Weber called "Tube Guitar Amplifier Servicing and Overhaul". Is that a good place to start? Thanks.
     
  2. RyanPitch

    RyanPitch Member

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    I've never seen the DVD, but I've got a few of his books. I also like to read other peoples' books and educate myself as much as possible. Then, the way I see it, you can go one (or more) of three routes when you want to start testing/fixing away:

    1.) Mess with your own, existing amp
    2.) Buy a used/cheap amp to start messing with it (I got an old Carvin X100b for $300 for this purpose)
    3.) Build a tube amp from scratch or a kit. I also did this and am mid-build right now.

    I feel like once you've done #3 or #2, you'll be WAY more comfortable doing #1.
     
  3. mark norwine

    mark norwine Supporting Member

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    Read "Valve Amplifiers" by Morgan Jones. You'll learn how tubes & tube amps actually function. This is a prerequisite, IMO.
     
  4. RussB

    RussB low rent hobbyist Silver Supporting Member

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  5. VaughnC

    VaughnC Supporting Member

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    Being a degreed pro electronic tech, IMO, to understand amp repair you need to get a grasp of basic electronics, the math behind it, and own and understand the basic test equipment needed for the job at hand (DVM, oscilloscope, signal generator, bias meter, etc.). I'd start by looking for a local school that has a basic electronics course that incorporates theory, math, & lab.
     
  6. Keyser Soze

    Keyser Soze Member

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    Old American Radio Relay League (ARRL) annuals (circa pre-transistor days - early 1960s and before) are a good source for understanding the basic electronics involved in tube amplification. They were written specifically for the amateur and cover all the basics. Shop around, one can usually be had for a few bucks.
     
  7. mooreamps

    mooreamps Member

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    Any place is a good place to start. However, depending on how high you want to go, if you did earn a two year degree in electronics or a 4 year degree in engineering, you could, then, apply to the US Navy and try to take a shot at becoming a US Navy ET. However, even with a degree, there is no guarantee you will not be washed out of A school. Their dropout rate is quite high.

    -g
     
  8. donnyjaguar

    donnyjaguar Member

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    What VaughnC says. You need to learn the rudiments before you can begin to understand the more advanced theory. Most of the guitar tech books I've read focus on tone and modifications and avoid the important things that went through the designers' heads during the first stages of development. I seldom comment on postings pertaining to "vibe", "tone", "capacitor choice" etc. because those threads start with and end in just a lot of BS.
     
  9. Roundtone

    Roundtone Gold Supporting Member

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    +1 - I learned a lot from this book, pretty easy read as well.
     
  10. jdh

    jdh Member

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    Louderock,

    Building kits like the Brownnote are worth their weight in gold. There are also many details that the math/academic world can answer. I submit it takes one part art and one part theory to get a grip on this craft. As an added bonus a degree will qualify you for many types of jobs. The only thing detrimental to school is it makes my brain hurt when I have to think.

    Dennis
     
  11. Trout

    Trout Member

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    I have found the old 40's Navy training manuals worth their weight in gold.

    Lots of theory, example circuits and formulas. Found several sets/years in junk stores and estate sales.


    +1

    Worth its weight in gold as well.
     
  12. louderock

    louderock Supporting Member

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    Looks like I need to buy this book by Morgan Jones. Be great to have the theory and understanding of the whole thing.
     
  13. ClinchFX

    ClinchFX Gold Supporting Member

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    I agree with both of these posts, but would add that it's necessary to also learn logical fault finding techniques for those times when swapping tubes, tapping components with a chopstick and looking for dry joints doesn't find the fault.;)
     
  14. louderock

    louderock Supporting Member

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    I agree with the above post. I'm not looking for a list of problems with another list of solutions. I want an understanding of why so I can get into the foundation of how and why it works the way it does. I think I'm capable of achieving this. I once was an electrical engineering student at Georgia Tech and always did great with math. I am now a recording engineer making records but have loads of amps and would love to be able to service/ improve them on my own.
     
  15. ClinchFX

    ClinchFX Gold Supporting Member

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    You have the right attitude, and that goes a long way.:AOK I agree that knowing the how and why is necessary in order to achieve what you want. After some time, the theory becomes part of your thought process and you no longer have to consciously recall it, except when you encounter a really difficult fault.

    My first 4 year course in electronics began in 1967, and I've never stopped learning since then. The last time I did any formal studies was 2001 -2003, just to catch up on areas where I felt a little weak.

    Peter.
     
  16. VaughnC

    VaughnC Supporting Member

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    IMO, it's one step at a time. Too many want to jump right into learning guitar amps but that's like putting the cart before the horse. You have to understand how a flashlight works before you can understand how a transistor or tube works, then you have to understand how a transistor or tube works before you can understand primitive preamp circuits, then you have to understand power supply circuits before you can understand amp topography, etc., etc....while learning the math behind it all and learning how to apply the proper test equipment.

    It took 2 years for me to get an Associates degree in electronics and there's good reason why it takes that long. IMO, there's no short cut to learning electronics...you need simultaneous theory, math, & lab to learn it the right way.
     
  17. plexistack

    plexistack Member

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    I was in the same position as you. I'm extremely interested in learning to service tube amps, and one day design and build them. I find it difficult to learn from a book or DVD without hands-on experience and being able to ask questions and be warned of pitfalls by an experienced amp master.

    So, I got a job working on amps at a local tube amp repair shop. There just happens to be one close by where I live.

    Even with my background in engineering, calculus, physics, differential equations, system dynamics, circuits, ect I was unable to comprehend stuff directly from a book.

    If you can do it, more power to ya.
     
  18. donnyjaguar

    donnyjaguar Member

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    For whatever reason that reminds me of the story of Edison tasking two of his interns with determining the volume inside an incandescent lightbulb. One student took a day or more to get back to him with a few pages of calculations showing the volume. The other took about 5 minutes and just busted the end off it, filled it with water and measured how much went in. Edison like this answer best.
     

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