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Amplifier repair courses?

Discussion in 'd.i.y.' started by rescuest3ve, Nov 4, 2019.

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  1. rescuest3ve

    rescuest3ve pfm Member

    Apologies if this in the wrong the forum! I can delete and repost if needed.

    I'm looking to expand my horizons somewhat and would love to get in to doing some kind of hifi / amplifier repair (or even cartridge retipping!) to keep myself active, but haven't the foggiest on where to start. I appreciate there's a helluva lot of literature out there (for amps, at least), but does anyone know of any hands-on courses (London/South East area) that would help with the basics first? Books are a wonderful resource of course, but without any practical experience, I fear they would be a waste of money, and whilst I was fairly handy at electronics in school, my practical knowledge is, in reality, zero...

    Cheers.
     
  2. Tony L

    Tony L Administrator

    There are some amazing YouTube channels covering audio amp theory, repairs and diagnostics. Checkout Blueglow Electronics, Electronics Old & New, and Uncle Doug for starters. The later is mostly valve guitar amps, but much the same and lots to learn. For more general electronics EEV Blog is very good. I tend to have this sort of content along with vintage computer restoration channels (of which there are many) on in the background and I do certainly seem to be picking some stuff up, though I’m still a way away from being able to fault-find (I can solder reliably and neatly so can recap working audio or computer kit etc).
     
  3. MJS

    MJS Trade: Consultant at WH Audio

  4. martin clark

    martin clark pinko bodger

    Great recommendation, @MJS

    Mr Carlson is excellent for long-form explanation videos, for years now. And he's always applied the same carefully explained diligent repair explication to the (often- ancient) tools he subsequently uses to then repair other items. It doesn't matter that a lot of tools of choice are valve-based - with and RF bias, often: the lessons, the carefully-explained methodology, are the same for any electronic repair task.
     
    Last edited: Nov 6, 2019
  5. rescuest3ve

    rescuest3ve pfm Member

    Amazing, thanks for the replies, guys. That's plenty to get my teeth in to for a good few months, I would say!
     
  6. Arkless Electronics

    Arkless Electronics Trade: Amp design and repairs.

    And for the totally opposite view.... you can't learn electronics from "how to" videos and "a little bit of knowledge is a dangerous thing".
    It WILL take many years to learn enough of both the theory and practical side before you will be doing less harm than good.
     
    narabdela, Zeusum, davidjt and 3 others like this.
  7. a.palfreyman

    a.palfreyman pfm Member

    Interestingly was reading up about class T amps and using air-core chokes on the output filters (on DIY audio). You couldn't guess that these act as antenna in the AM band which could get you into trouble!
    AP
     
  8. Arkless Electronics

    Arkless Electronics Trade: Amp design and repairs.

    In one of my past jobs in R&D we had to abandon class D as it could interfere with emergency services radios. I'd been trying to kill the project off for 2 years but this finally did it!
     
    a.palfreyman likes this.
  9. cooky1257

    cooky1257 pfm Member

    Cartridge re-tipping to keep you active;-)....I can't think of any 'occupation' that would demand you remain more still.
     
    lazycat likes this.
  10. martin clark

    martin clark pinko bodger

    +1 for need this practical side.

    One route might be to buy a reputable and well-documented kit for something you'd find useful - say from Velleman, a preamp or the like - and try building it: so you not only understand what the outcome it, but how it works and practice of troubleshooting in the build. Once you have it running you can go around the circuit and really study it , find thr AC and DC voltages and currents in each element and use it for study/ developing comprehension of how it really works, without imperiling anything more complex.
     
    rescuest3ve likes this.
  11. Jim Audiomisc

    Jim Audiomisc pfm Member

    The above seems a good idea to me. The snag is the relative sparsity these days of examples of kits of good audio equipment. The old way tended to be a mix of home DIY for years - when magazines published designs - or 'sitting next to Nellie' at work. Which these days might be more like finding a local 'Guru'. I have wondered if any "man shed" groups in the UK get into audio, or if it is all woodwork/metalbashing/car-repair.

    FWIW in recent years I've occasionally bought a cheap kit from CPC to give me a circuit board and components, then bodged something different onto the board. This can be handy for small experiments.

    Decades ago I learned a lot from HFN articles. But back then they would publish DIY designs and advice, and run technical articles on how things worked, etc. Alas, UK audio mags are now essentially 'consumer' focussed and don't want to scare away readers with complicated stuff like circuit diagrams or technical details which risk them needing to know some basic maths, etc.

    Finding items from ye olde Wireless World on the americanradiohistory site might help, though. (You can tell I'm old fashioned as I prefer text and diagrams to videos. :) )
     
    Julf and rescuest3ve like this.
  12. Arkless Electronics

    Arkless Electronics Trade: Amp design and repairs.

    I'm with you on that one! I'm a proud Luddite and would generally ignore anything that was a video and not text with diagrams!
     
  13. rescuest3ve

    rescuest3ve pfm Member

    This is why I wanted to go to some sort of course, see: to make sure I know how NOT to kill myself before I start tinkering.
     
  14. colasblue

    colasblue pfm Member

    Is there any part of not doing a completely crap job due to lack of qualifications and previous experience you might like to consider?

    When I was at uni our student bar was called the Gorton and District pensioners Hang gliding Society. Perhaps you'd like to be its first genuinely interested member?????
     
  15. Jim Audiomisc

    Jim Audiomisc pfm Member

    To avoid death, two rules ab intio.

    1) Only make things you can power from a few AA cells or PP3's.

    2) Use a bench PSU that will go up to about +/-40V and has an adjustable current limiter.

    ...erm, OK, three rules

    3) Work on a surface that insulates and isn't easily flammable 8-]

    Star with small low voltage/current circuits, and work yer way up. Cheaper way to learn than burning the house down. :)

    I don't know what you may have already done. But an easy audio start is to build some of the small kits for, say, a headphone amp, tone controls, etc. Then experiment to see how they could be improved. Show your working on the DIY section so others can chip in.

    For something like a preamp or tone controls batteries can work very well. Their drawback is ensuring they are charged/replaced as needed. But once something works well with batteries you can worry about a mains PSU if you need one.

    Creep up on power amps by making low power simple ones first. Then use at first with a bench psu. Look at it this way: A 40V few amp bench supply means you can get over 100 watts peak. And initial tests can be with lower voltages and the limiter wound down a bit to avoid singeing your eyebrows if the circuit is wired up badly.

    Initial tests with speakers should use a fuse in series. Yes, it messes up the sound a bit, but can save the speakers. Easier to replace a fuse than a speaker.
     
    Julf and rescuest3ve like this.
  16. Arkless Electronics

    Arkless Electronics Trade: Amp design and repairs.

    A build yourself an amplifier class would be more practical... A simple valve pre or similar. I had this idea maybe 25 years ago and was thinking of combining it with top nosh made by a near Michelin star chef mate who is an audiophile... a weekend residential course for say £1K and you take away the amp you've built.
     
    rescuest3ve likes this.
  17. a.palfreyman

    a.palfreyman pfm Member

    That made me smile, does it mean he's nearly a Michelin star chef!

    To the OP, Elliott Sound Products also has some good technical stuff you can read up on his website:
    https://sound-au.com/

    AP
     
  18. Arkless Electronics

    Arkless Electronics Trade: Amp design and repairs.

    You've left me on that one.... is that not what I said?
     
  19. Tony L

    Tony L Administrator

    Rift Amps, a maker of really good valve guitar amps (I have one), run a course which seems exceptional value at £1299 given you end up with a lovely point to point-wired boutique guitar amp (link).
     
    rescuest3ve likes this.
  20. Shadders

    Shadders pfm Member

    Hi,
    I think it was a play on words. Near as in close, as opposed to near as in not quite a Michelin starred chef.

    Regards,
    Shadders.
     

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