Gibson GA8 vs GA9

Discussion in 'Shock Brother's DIY Amps' started by Mongo Park, Apr 7, 2018.

  1. Mexitele Blues

    Mexitele Blues Tele-Meister

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    You're welcome. I plan to keep an eye on your build, hopefully I'll learn something.
     
  2. Mongo Park

    Mongo Park Tele-Holic

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    Iron has already arrived and I have a sheet I will try to bend into shape. As in the correct shape. That is one monsterly big OP transformer, should really put out. I am still collecting parts so it will be slow. I will start a new thread once I get going.
    Cheers Ron. IMG_0149.JPG IMG_0151.JPG
     
  3. Mongo Park

    Mongo Park Tele-Holic

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    I want to revive this thread to thank Mexi-Tele Blues for sharing his point to point schematic with me for this build.
    It has been a few months but is now lives.
    I bent up a Chassie of aluminum and painted it hammered copper colour for some reason this seemed a Gibson like colour. I also made it to sit in the bottom of the cab like a early Gibson. It took a bit of messing with to have it fit in the cab and not have any parts hit the speaker magnet. I was going to use a Canibus Rex speaker.
     
    Last edited: Feb 10, 2019
  4. Mongo Park

    Mongo Park Tele-Holic

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    Here is what it looks like. I have 4,8,&16 ohm outputs which I stills have to connect, running 8 home now. I added a negative feedback switch to cut it, which was the only mod so far.
    I have killer iron from Matt at musical power supply, world class products he has for sure. 33k output transformer for the parallel 6v6’s.
    I am running some “Russian” powere tubes I imagine these thing coming from tank and now happily powering the blues.
     

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  5. Mongo Park

    Mongo Park Tele-Holic

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    The inside is point to point which I am happy to see more builds like this on the forum. I sort of started out this way and have continued on.
    Lots of space to get it all in and not to rats nest looking. I did the heaters up high so they could drop down from above the tube, worked well no hum.
     

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  6. Mongo Park

    Mongo Park Tele-Holic

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    I am wanting to separate the shared cathode resistor/cap. I thought I could bias them separately, but now wondering if I could put in a 6V6 and a 6L6 tube. I have read about switching 6V6 to 6L6 but nothing about one of each. I have the current to run the 6L6 and the output transformer is built to handle it but it is 33k and I don’t know how that will come into play.
    Any input would be appreciated.
     
  7. Mexitele Blues

    Mexitele Blues Tele-Meister

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    Looks fantastic Mongo, congrats.

    Am I correct in assuming that the 6V6's bias resistor would bias a 6L6 on the cold side?
     
  8. Mongo Park

    Mongo Park Tele-Holic

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    If i seperate them the cathode resistor for the 6V6 would be 470 ohms.
    6L6 I am thinking around 250-350 ohms, just as you said, but it also involves the plate voltage and output transformer impedance.
    For my limited knowledge more reading is needed, maybe stare a new thread.
    Cheers Ron
     
  9. Nickfl

    Nickfl Tele-Afflicted

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    I like that you painted the transformer end bells too, thats some nice attention to detail!
     
  10. bigguy12321

    bigguy12321 Tele-Meister

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    Mongo

    Not sure if you have seen this one but here is Magnatone's version of parallel 6v6's.

    May be good for future mods.

    Amp looks great by the way. I really dig point-to-point and yours is very clean.


    magnatone_109-melodier_sch.pdf_1.png

    a
     
  11. Wally

    Wally Telefied Ad Free Member

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    Kudos, Mongo.
     
    Last edited: Feb 11, 2019
  12. FenderLover

    FenderLover Friend of Leo's

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    Look close at the output transformer - the 6V6's are configured for self-splitting and the output is P-P.
     
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  13. bigguy12321

    bigguy12321 Tele-Meister

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    Oops. I should slow down at 1:30am... Thought I saw something I didn't.

    a
     
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