6550's in a Fender Twin RI

Discussion in 'Amps/Cabs Tech Corner: Amplifier, Cab & Speakers' started by mbruffey, Mar 19, 2006.

  1. mbruffey

    mbruffey Supporting Member

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    Would 6550's work in a Fender Twin RI (15"-'05) with nothing more than a bias adjustment? Would they stress transformer(s)? Thanks, Mark
     
  2. Dave C

    Dave C Gold Supporting Member

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    Yes they would stress transformers , heater current is almost double for one thing(1.6a vs .9a). For more power and headroom I'd suggest 7581a which is a drop in and rebias replacement.
    Dave C
     
  3. donnyjaguar

    donnyjaguar Member

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    Wow, that filament only draws 1.6mA ? ;)
     
  4. Swarty

    Swarty Member

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    So just try a pair. They bias very closely to 6L6s. A pair will also match up closer to the 4 ohm load than a quad would.
     
  5. Dave C

    Dave C Gold Supporting Member

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    Oops, sorry guys I had the heater current as ma instead of amps , my bad , it was late , I've edited my post to reflect this.
    Dave C
     
  6. mbruffey

    mbruffey Supporting Member

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    hmmmm, I run duets in the Twin all the time, as it's cheaper to test different output tubes.

    2 x 1.6 = 3.2
    4 x .9 = 3.6

    So two 6550's would actually be easier on the tf than 4 6L6's. Am I right? If so, I might try them.

    Mark
     
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  7. Dave C

    Dave C Gold Supporting Member

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    Sounds like a plan to me Mark . I'd give it a whirl.
    Dave C
     

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