Next up a PSE Flea powered amp - the Mighty 71-A

Discussion in 'Tube Audio' started by analog addict, Feb 19, 2018.

  1. Ziradog

    Ziradog AK Subscriber Subscriber

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    +1
     

     

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  2. analog addict

    analog addict Glory or Death!

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    Cleaning up a vintage terminal strip to populate the underside of the chassis. I prefer vintage terminal strips, since they tend to be higher quality then the current Rat Shack type stuff.

    [​IMG]Untitled by Analog Addict, on Flickr

    Have the underside of the chassis populated. The second 5V filament transformer is not gonna be secured in until I can get the inputs and outputs wired up due to ease of work considerations.

    [​IMG]Untitled by Analog Addict, on Flickr

    Unfortunately, the Honey Dew list is calling, so amp building will have to be put on hold for awhile....
     
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  3. s-petersen

    s-petersen Scott Subscriber

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    :lurk: watchin'
     
  4. Tubeglowpio

    Tubeglowpio Active Member

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    Very nice, cant wait for impressions. Were you able to post a schematic for the 45 amp? I'm about to pull the trigger on a 2a3 schematic but a parallel 45 might do he trick.
     
  5. analog addict

    analog addict Glory or Death!

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    Trying a different process this time. Instead of starting with the power supply, I wired up most all the grounds, including the PS caps.

    [​IMG]Untitled by Analog Addict, on Flickr

    Here's where the other 5V transformer will go once the signal side wiring is in....

    [​IMG]Untitled by Analog Addict, on Flickr
     
  6. analog addict

    analog addict Glory or Death!

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    Progress. PS is mostly done, along with the VR circuit. Starting to wire the high voltage side up, but realized I may need a couple of 750 ohm/12W resistors for the cathode circuit. Oh well....

    [​IMG]Untitled by Analog Addict, on Flickr
     
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  7. analog addict

    analog addict Glory or Death!

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    Almost done. Mocked up the final configuration and will be taking some of the superfluous terminal strips out. Also need to run the parallel wiring on the 71A filament and plate connections. The Jensen coupling caps will go in last.

    Soon....

    [​IMG]Untitled by Analog Addict, on Flickr
     
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  8. Mike Stehr

    Mike Stehr Poverty Audio

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  9. s-petersen

    s-petersen Scott Subscriber

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    If those large resistors get hot, I think the heat may not be so good for the caps.
    I think it looks great otherwise.
     

     

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  10. analog addict

    analog addict Glory or Death!

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    Yeah I hear you. That's the common cathode resistor/capacitor set up for the three 71-As. I happened to find a dual resistor of the right value in the box of power resistors. The plan is to bend them away from the resistor(s) towards the bottom plate once everything is soldered into place. Also, hopefully the heat will rise away from the caps once in operating position....

    [​IMG]Untitled by Analog Addict, on Flickr
     
  11. s-petersen

    s-petersen Scott Subscriber

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    I was talking about the green and white ones on the other caps, unless they are temporary.
     
  12. analog addict

    analog addict Glory or Death!

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    Hmmm. I see what you mean. I'll have to check how much power is being dissipated in those resistors. Thanks for the heads up
     
  13. analog addict

    analog addict Glory or Death!

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    Why amp building is a labor of love for me....

    [​IMG]Untitled by Analog Addict, on Flickr

    Or an expression of my OCD/ADD/other abby-normal tendencies and habits.

    [​IMG]Untitled by Analog Addict, on Flickr

    Well, didn't have much time today, given that mulch shoveling took precedence over amp building on SWMBO's list. So, all I got to was the plate wiring from the OPT. Still moving forward however...

    [​IMG][​IMG]Untitled by Analog Addict, on Flickr
     
  14. analog addict

    analog addict Glory or Death!

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    Got a little more ambitious. All that's left is one of the 6SN7 sockets to wire up. Should be done by Sunday

    [​IMG]Untitled by Analog Addict, on Flickr
     

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