My project "JLH-69"

Discussion in 'DIY' started by Zampotech, Feb 8, 2019.

  1. mdr30

    mdr30 Acquaintance

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    I'm a bit confused regarding discussions of power/headphone amps in this thread, but if you have a JLH germanium headphone amp going (kit or finished) I would certainly be interested. My SW51 is doing excellent service.
     
  2. Zampotech

    Zampotech Friend

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    A small update to this forgotten theme. The day before yesterday, we received a long-awaited batch of printed circuit boards, including boards for the JLH-69 power amplifier

    [​IMG]

    There are no ready-made amplifiers now. There is only a prototype. The production of amplifiers on germanium transistors was frozen due to the lack of the possibility of manufacturing cases.
    Now I have the opportunity to make cases, and this project will be unfrozen.
     
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  3. Cspirou

    Cspirou They call me Sparky

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    oooooooo

    I assume PCBs are available for sale?
     
  4. Zampotech

    Zampotech Friend

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    I think this project can be open and anyone can order these printed circuit boards. Direct delivery from the manufacturer is likely to be cheaper

    Link to order directly from the manufacturer.

    Of course, this is for amateurs who know which side to take the soldering iron from:)

    PS I will provide the layout of the elements and the electrical diagram a little later.
     
    Last edited: Mar 18, 2021
  5. Sqveak

    Sqveak Friend

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    What kind of pricing are you aiming for with the MAGISTER?

    Is it possible to anodise the heatsinks to match the body of the ampifier or reduce contrast with the wood stain?
     
  6. Zampotech

    Zampotech Friend

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    The estimated cost of the amplifier will probably be $340-$360

    I have already given these coolers for electroplating before. To be honest, it turned out badly, it turned out not a deep black color, but an incomprehensible brown.
    I was advised to change the technology to create an oxide film with further boiling in an aniline dye. Maybe everything will turn out well.
    Of course, the combination of black, silver and wood color hurts the eyes.
     
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  7. BobApelsin

    BobApelsin New

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    pcb was made and delivered half their estimated time .Now just knowledge of rest of components :)
    regards magnus
     
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  8. Zampotech

    Zampotech Friend

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    Schematic diagram of the amplifier with the nominal values of the elements. a little later I will give a picture of the arrangement of the elements. The amplifier needs a stable +24 power supply..30V/5A

    [​IMG]
     
  9. joch

    joch Friend

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    This is madness! I want one just for its cute VU meter eyes!
     
    Last edited: Mar 26, 2021
  10. Zampotech

    Zampotech Friend

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    For those who made this PCB, I publish the location of the elements.

    [​IMG]
     
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  11. Superexchanger

    Superexchanger Friend

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    Dropping by for the first time in a few months to acknowledge the elegant solution to the VU metering issue. Just superb.
     
  12. msommers

    msommers High on Epipens

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    +1 I'm in
     
  13. Sqveak

    Sqveak Friend

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    If this equates to joining a queue then I'm waiting in line.

    Sign me up for one magister speaker amp please!

    @Zampotech how many are you planning to make once your design graduates from prototype to production?
     
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  14. Zampotech

    Zampotech Friend

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    I don't have a list yet, and I don't know the number yet. Now I devote all my energy and time to the production of SW51, because I am behind the production schedule. After I start sending, my hands and head will be free and I will seriously take up other projects, including JLH 69.
    The rest of the projects can be completed much faster, since the most slippery stage of work, the production of enclosures, is now in my hands and I do not depend on suppliers.
    Potentially the maximum number of JLH69 now is 34 pieces (according to the number of VU meter) Probably this amount will be enough for everyone.
     
  15. Empyah

    Empyah Facebook Friend

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    Hi,

    very interested in your work, and it is a pleasure to watch your enterprise and number of satisifed customers
    grow over the months.

    Wanted to ask if anything changes with the power output in watts at 8 Ohm of the amp (I barely understand the basics of eletronic engineering and wonder if the power will be enough to get 87db bookshelfs loud in a 16 by 23 feet room) other than the design being improved with better parts than the Alibaba "original"?

    And if you can still use the speaker version with headphones like the HE6 with an adapter?

    Thanks in advance for your answer and all the best to you and your company!

    Edit: and please count me in on the list if possible! :) +1
     
    Last edited: Apr 29, 2021
  16. Zampotech

    Zampotech Friend

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    To get the highest power with minimal distortion from the JLH 69 amplifier, you need to adjust the electrical mode (the power supply voltage and the rest current of the transistors) for a specific load.
    This means that it is expected to produce two models of this amplifier. One for a load of 4-6 ohms, the second for a load of 8-16 ohms. Of course, the JLH 69-4/6 model can work with a load of 8-16 ohms, and vice versa. But the maximum power in this case, the amplifier will not give.
    This, of course, to some extent deprives it of its universality. But the musicality of this amp makes up for this disadvantage.
    The maximum power of this amplifier is 2x10 watts. For a room of 16x23 feet and a speaker sensitivity of 87 dB, this amplifier can provide a comfortable volume, but will not be able to provide listening to music with your stomach, as in a nightclub. For this amplifier, speakers of higher sensitivity are suggested.

    PS A universal amplifier for a load from 4 to 8 ohms is technically possible. But it will be a cyclopean design because of the huge radiators. In such an amplifier, the quiescent current should be as for a load of 4 ohms, and the supply voltage as for a load of 8 ohms. This will increase the heat load on the radiators by about 4 times. We must not forget that the JLH 69 is a Class A amplifier, where most of the power consumed goes into heat.
     
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    Last edited: Apr 30, 2021
  17. Empyah

    Empyah Facebook Friend

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    So which one would be the correct for my speakers - I presume the 8-16 Ohm version is for headphones?
    I am not sure since the Alibaba version says it is set up for loads of 4-8 Ohm.

    Edit: Incoherent jibberish
     
    Last edited: Apr 30, 2021
  18. Zampotech

    Zampotech Friend

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    For your 8 ohm speakers, the 8-16 ohm version will be optimal.

    I am sure that Chinese engineers know about the features of the JLH amplifier that work best with a specific load, but Chinese (and not only Chinese) marketers have their own special opinion on this.
     
  19. Friday

    Friday Friend

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    What about 8 ohm speakers that dip to 4 ohms in the bass? I am guessing the 8-16 ohm version is still more suitable
     
  20. Zampotech

    Zampotech Friend

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    Yes, version 8-16 will be better
     

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