help with a little tube amp design

Discussion in 'The Projects Forum' started by simon74, Apr 8, 2010.

  1. simon74

    Thread Starter New Member

    Apr 8, 2010
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    hi guys well lovely looking site .
    anyway iam looking to build a little tube amp.
    i have some tubes laying around old ones
    and a power an sound transformer
    well i have allsorts of old bits an bobs lying around .
    and well ive been looking around the net ,seeing if possible to build a small custom
    amp with parts i have and can source with little cash .

    now i have some tubes an ecc83 ,an ecl82
    im not lookign to build a pumping amp just somthing really as a learning piont.
    as always with learning instruments well always looking for the next challenge.
    so if anyone out their would or could offer help in possibly designing a small
    amp around 1 or both these tubes ,i would really appreiciate it .
    and well if i could help you in anyway at all i would love to .
    so please any great amp men out their please
     
  2. SgtWookie

    Expert

    Jul 17, 2007
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    The ECC83 is equivalent to the 12AX7A, which are high-mu (high gain) twin triodes.
    The characteristics and curves are the same as type 6AV6.

    Usually, you'd want to use something like a 12AU7A or 12AY7, which are medium-mu twin triodes for an audio amplifier. With the ECC83, you may wind up with excessive noise due to the high gain. Hissss...

    The ECL82 is equivalent to the 6BM8; it is a high-mu miniature triode/power pentode, designed for use in TV applications. The pentode unit is used as an audio output tube, and the triode used as as an oscillator and/or audio frequency voltage amplifier.
     
  3. simon74

    Thread Starter New Member

    Apr 8, 2010
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    Thanks for the responce.
    I was looking at the small tube amp
    in the tutorals section,
    somthing i may have a go at.
    but im not understanding the car starter motor.
    Also i have been spending lots of time reading up on the tubes,
    also the dangers.all advise appreiciated.
     
  4. Bychon

    Member

    Mar 12, 2010
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    Thanks for describing the tubes in American terms, wookie. Almost all early guitar amplifiers started with a 12ax7 (ecc83) and I think the 6BM8 would make a good tone recovery stage and audio output. After all, these 2 tubes represent one more gain stage than a Fender Princeton or an early Supro. I say it's a guitar amplifier waiting to be born.
     
  5. SgtWookie

    Expert

    Jul 17, 2007
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    One topic per thread, please - otherwise, things get confused very quickly. If you need help with the car starter motor, please start a new thread with a new subject title something like "Confused about car starter motor".

    Tubes/valves require a high voltage supply in order to work properly. You must use extra caution when working with such high voltages.

    You need to start by finding datasheets for the ECL82 and ECC83 tubes/valves. I have them in a book, but my scanner is down at the moment.

    Finding the datasheets for electronic devices is really a fundamental skill that you will need. I suggest using the Google search engine, using appropriate keywords.

    Note that the plate voltages for the two halves of the ECL82 are different; the triode (100v typ) being about 1/2 the pentode (200v typ).
     
  6. SgtWookie

    Expert

    Jul 17, 2007
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    I actually did that more or less for my own convenience, as I looked them up in my vintage 1970 RCA Receiving Tube Manual that I bought as a teenager. The manual has lots of details, but it's sorted by the American numbers, not European numbers - which makes the process rather like an Easter egg hunt. ;)

    If I had Googled them to begin with, it would have saved me a good bit of time. Note that if you start a Google search for the ECL82, 6BM8 pops up before you even have a chance to hit Enter! :eek: :cool:
    That sounds like an interesting idea. ;)

    Since this is a "Ye Olde Junque Bachs" type of project, probably the next thing to do (after our OP locates the datasheets for the tubes/valves) is to figure out what the voltage and current ratings of the transformer inputs/outputs are.

    He'll also need some high voltage caps for the plate supply. If he's going to use salvaged electrolytic caps, re-forming the dielectric will be another little task to perform.
     
  7. simon74

    Thread Starter New Member

    Apr 8, 2010
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  8. SgtWookie

    Expert

    Jul 17, 2007
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    Well, see if you can find a schematic for the device that you salvaged the components from. That will be a help in determining what you have.
     
  9. simon74

    Thread Starter New Member

    Apr 8, 2010
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    ive been given these shcametics to look at .
    And have been told are based upon the same.
    Other than these i will have to seriously dig to find the actual petro scott schametics.

    and thankyou very much.
    fidelity3.jpg
     
  10. bertus

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    Apr 5, 2008
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    Last edited: Apr 8, 2010
  11. simon74

    Thread Starter New Member

    Apr 8, 2010
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  12. Wendy

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  13. simon74

    Thread Starter New Member

    Apr 8, 2010
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    hello ,and yes, i have looked at the tube amplifier in the text book.
    The automotive ignition coil,I don t have ready at hand.
    I also found it a very interesting read.one of the best tutorials
    I have found on any website.also lots more Interesting and easy to learn projects.
    of which i have spent most of the day reading through.
    Now iam looking to get more hands on,as i do learn more this way.
    and look forward to learning more everyday,i might be getting old.
    But well never too old to learn ,thankyou ,simon :)
     
  14. bertus

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    Apr 5, 2008
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  15. simon74

    Thread Starter New Member

    Apr 8, 2010
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    many thanks bertus.

    well i have been reading an reading.
    i now think my best option is to start doing the simple things,
    and well get a good grounding on them.
    i do now think my thought and expectations were possibly too high.
    and well,i do realise i should keep things basic learn a little slower.
    do some small tutorials and experiments,before attempting any larger projects.
    iam certainly learning more by the day i must admit,and a nice guitar amp
    one day,would be lovely to build,as i like to build my own cigarbox guitars.
    well most the reason that triggered my idea to try my own amp,and well tube,with it being i beleive the best sound ,but never having owned 1.
    so yes well step by step iam sure i will get to building an amp to play my
    homemade guitars through .and also thanks for all the great help.
    i really appriciate it ;)
     
  16. bertus

    Administrator

    Apr 5, 2008
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    simon74 likes this.
  17. simon74

    Thread Starter New Member

    Apr 8, 2010
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    thanks bertus.
    well certainly one for me to read their .
    much appreiciated ;)
     
  18. Bychon

    Member

    Mar 12, 2010
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    41
    My favorite tube book is, Beginner's Guide to Tube Audio Design by Bruce Rozenblit. It is beginner level, but it has the math, and it is a handy reference for all those things you have to look up because you're so used to working with transistors.
     
  19. simon74

    Thread Starter New Member

    Apr 8, 2010
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    iam so used to working with transistors ,:rolleyes:
    forums dear me.
     
  20. 100Dave

    New Member

    May 4, 2010
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    for anyone reading this whole post, i believe that the original poster was refering to the project located here :http://www.allaboutcircuits.com/vol_6/chpt_5/19.html

    When he references "car starter motor" I think he means the ignition coil that is used in the circuit which is from an automotive application.
     
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