Starting a Stromberg Carlson ASR-444 amp build

Discussion in 'Tube Audio' started by s-petersen, Jan 12, 2018.

  1. primosounds

    primosounds SE KT120 w/ 6J5G drivers. LCLC ps + 2 x 5ar4 Subscriber

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    Terra, 21st century CE
    In Lieu of the 6u8 try the ecf82. It should be a better all around tube. I believe it is a drop in replacement
     

     

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  2. knockbill

    knockbill Addicted Member

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    7,351
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    Very nice,,, what are those flat yellow caps?
     
  3. s-petersen

    s-petersen Scott Subscriber

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    4,329
    Location:
    Middletown,New York
    I'll see if I have some ECF-82''s, Thanks!
    The flat caps are 3.9 mfd 350v polypropylene caps, I bought about 100 of them about 15 years ago
     
    Last edited: Feb 16, 2018
  4. s-petersen

    s-petersen Scott Subscriber

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    4,329
    Location:
    Middletown,New York
    I still have to figure out the cathode balance circuit, and add balance pots and a cathode bypass cap, I decided to keep the tube sockets to provide a balance check
    I still have some temporary parts installed, The input jacks are just for testing.
    pilot lights.jpg close.jpg
     
  5. knockbill

    knockbill Addicted Member

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    7,351
    Location:
    SE PA
    Another winner!! did you listen to any music yet?
     
  6. s-petersen

    s-petersen Scott Subscriber

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    4,329
    Location:
    Middletown,New York
    Just started. It sounds pretty good on my test speakers, without the bypass caps installed, At least this one is quiet, it has almost no hum with my ear to the speaker. My "Mullard type" amps had a background noise level that was not ideal,I think the power transformer coupled to the chassis and gave me some hum I couldn't quite get rid of, The EF-86's also had a bit of rush in the background as well.
    I think I have to adjust the bias down a little. 6L6GC 445v 50ma 300 ohm cathode resistors.
     
    Last edited: Feb 14, 2018

     

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  7. knockbill

    knockbill Addicted Member

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    7,351
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    Sounds very promising,,, some of the PTs I'm measuring have Faraday shields, they may help the PT noise problem,,, this amp looks like it will put out some power... I have an amp or two I built that could use a quieter PT, and/or choke,,, plan to look in to it soon..
    I just noticed the wire notch you cut for the transformer, nice touch...
     
  8. s-petersen

    s-petersen Scott Subscriber

    Messages:
    4,329
    Location:
    Middletown,New York
    That was actually a factory Dynaco design, I haven't modified the SS chassis,except the holes for the cap mount had to be elongated. This chassis is a tank, laser cut and pretty thick.PITA to cut and modify, else I would have cut out the original cap mount out, instead of making a dummy cap to fill it.
     

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