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Octal Bassman?

Discussion in 'Shock Brother's DIY Amps' started by James Ryan, May 28, 2010.

  1. celeste

    celeste Friend of Leo's

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    Being a believer in getting it working right first, lets start with #2.

    My first bet would be a grounding issue at ether the input jacks or the volume pots. Looking at the layout for a 5F6A on schematic heaven, I am reminded why I hold the grounding of old fenders in such contempt.

    Try using clip leads from signal ground to the jack you plug in to and see it that kills the cross talk. If not move the lead to the volume pots and the lug that is grounded.
     
  2. imsilly

    imsilly Friend of Leo's

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    I had an early Fender Deluxe with octal preamp tubes, sounded HUGE when overdriven. Though it did have less gain then later Deluxe's I've heard and less clean headroom. Still sounds like a great idea.
     
  3. James Ryan

    James Ryan TDPRI Member

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    Well, I tried the clip lead idea. Nothing, other than a small reduction in hum, which I addressed by trying another ground configuration with the volume pots.
     
  4. ThermionicScott

    ThermionicScott Poster Extraordinaire

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    Hey, you're getting sound out of it and you haven't fried anything expensive. You're most of the way there -- that's a reason to be hopeful. ;)

    Just for kicks, would you mind posting the voltages on all the pins?
    Are the #2 inputs a little quieter than the #1's? If you're following a layout diagram, perhaps your jacks have the tabs arranged differently.

    That's all I can think of for now.

    - Scott
     
  5. rainedave

    rainedave Tele-Holic

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    I have no idea if this would be of any help, but here's the input detail from the Weber 5F6-A kit. At least it's more clearly drawn.
     

    Attached Files:

  6. James Ryan

    James Ryan TDPRI Member

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    Hey, Scott and rainedave, thanks for the tips. I've been really busy the last week or so and the amp project is kind of on the back burner. But I will take another look at the tab configuration. I'll take some exact voltage measurements again to be sure, but they were pretty on spec according to the voltage sheet I have. I remember pin 6 on the power tube being 456v, which might be a tad hot. I'll post the exact measurements in a day or two.
     
  7. M Fowler

    M Fowler TDPRI Member

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    What filter caps are you using, there on the back in a cap cover or are you using can cap? I didn't see the power supply in the photos.

    Mark
     
  8. rodneyo

    rodneyo NEW MEMBER!

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    Hey! I think i picked up this amp on ebay. James…any thoughts one what is the issue? I replaced the missing output transformer and choke and reconnected the severed wiring.
     
  9. syrynx

    syrynx Tele-Afflicted

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    Bump, in the hope this amp can be fixed.
     
  10. rodneyo

    rodneyo NEW MEMBER!

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    Just got the amp back. Had to send it to someone more knowledgeable. It is up and running and sounds wicked! Ballsy and gritty. Will post pictures.
     
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