DIY talk

Discussion in 'DIY' started by Cspirou, Jul 25, 2021.

  1. Cspirou

    Cspirou They call me Sparky

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    I could have sworn there was a general DIY thread but I couldn't really find it.

    Anyway, this is for questions and comments that don't really merit a dedicated thread but are interesting or useful nonetheless.
     
  2. Cspirou

    Cspirou They call me Sparky

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    Starting myself;

    Is there a reason for encasing electronics in epoxy besides trying to prevent cloning?
     
  3. Woland

    Woland Friend

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    Water resistance. The circuit board of my coffee machine is like that.
     
  4. Beefy

    Beefy Friend

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    Also vibration resistance. Important if you are going to send your amp into space.
     
  5. Thad E Ginathom

    Thad E Ginathom Friend

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    I used to make that stuff in one of my hippy-days jobs. I think the brand name was eco-fill. IIRC it might have been an American company, but had sales and some manufacturing facility in West London, UK.

    A couple of guys from the same house worked there, running the huge-rollers machine that mixed and fused the mix. I made up the mix.

    Weird business: almost every batch failed inspection and was chucked out! One day there was an almost perfect batch. The lab guys from upstairs were quizzing me: "Please, please, try to remember what you did different!" I couldn't: it had been just another mix to me.

    One of the ingredients was a very fine carbon powder. It took a week of baths to get it out of the skin pores, so I looked permanently like a 19th-century chimney sweep.

    The place was very low on safety standards, and the day the three of us left, the foreman (who was even related to the MD) left us alone in the office with the phone book pointedly left open at Factory Inspectorate!

    Anyway, not entirely offtopic, but not very useful, this has been My Life In Potting Compound...
     
  6. dBel84

    dBel84 Friend

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  7. Woland

    Woland Friend

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  8. randytsuch

    randytsuch Friend

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    I've seen potting used to prevent arcing in high voltage circuits, especially at high altitudes (airplanes).


    On the diy front, I'm considering building a Class A, pass or firstwatt clone amp to drive my HE6SE's. Might be my next project.

    Randy
     
  9. Cspirou

    Cspirou They call me Sparky

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  10. Beefy

    Beefy Friend

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  11. Cspirou

    Cspirou They call me Sparky

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  12. Cspirou

    Cspirou They call me Sparky

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    Yeah. It seems like his other was a proof of concept. Single rail power supply so capacitors on the input and output. Plate voltage on the nutube is only 24v also.

    On the Sangaku it's a full blown regulated dual rail power supply with B+ at 70V and 40V at the plate. 3rd order distortion is 20dB lower on the Sangaku than the simpler amp.
     
  13. Beefy

    Beefy Friend

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    Indeed. But after a bit more thinking about this, I'm really just a bit bummed about the use of output OPAMPs here. As someone who built several Millett hybrid derivatives with the discrete diamond buffer output, this just seems a bit less fun to put together.
     
  14. Armaegis

    Armaegis Friend

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    I suppose one could always put sockets in and DIY a discrete opamp?
     
  15. Beefy

    Beefy Friend

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    I've never really looked that closely at discrete OPAMPs, are there any suitable for unity gain current buffers?
     
  16. Armaegis

    Armaegis Friend

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    I don't know any off the top of my head other than the pre-made ones by Burson, Sparkos, NewClassD, Sonic Imagery, etc...

    There's a few more in the music/guitar world, but I'm not really familiar with them.
     
  17. Cspirou

    Cspirou They call me Sparky

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    I'm not sure if First Watt amps have enough voltage for an HE6. A typical First Watt supplies 25W into 8Ω which will give you 4W into 50Ω.

    I mean 4W should be enough but I know people that look for more
     
  18. randytsuch

    randytsuch Friend

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    Thanks for the warning. Haven't made any progress, but I hope to soon.

    I suppose I could make a higher voltage power supply, with lower bias current.

    Randy
     
  19. Cspirou

    Cspirou They call me Sparky

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    Pete Millett is really just a tube guy. If you look at his catalogue almost none of his solid state circuits are discrete, preferring to use monolithic components whenever possible. This goes for opamps, regulators and CCS loads. He's often used switch mode supplies as well
     
  20. Armaegis

    Armaegis Friend

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    It's probably enough, but most of us want the bragging rights... o_O
     

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