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Headroom, Chokes, and Transformers -- Tweed Pro, Super, and Bandmaster

Discussion in 'Amps/Cabs Tech Corner: Amplifier, Cab & Speakers' started by sabby, Dec 23, 2005.

  1. sabby

    sabby Member

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    I'm interested in making -- er, having made -- a Weber 5E5A/5F4/5E7 kit with Mercury Magnetics choke transformers. I want to be able to run both 6V6s and 6L6s, with the former probably getting most the work in the small places I get to play.

    I'm interested using in lowering the headroom and output. So I'm thinking of using the smaller Pro choke and a Pro multi-tap OT. I understand these are the smallest. I'm also thinking of using the low B+ tap on the Weber PT.

    Does anyone here know if this will reduce the actual output from say 20w (6V6)/35w (6L6) to around 15w/25? Or, will this configuration just be more flabby and compressed than going with the 5F4/5E7 choke and OT?

    Thanks. :BEER
     
  2. bob-i

    bob-i Member

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    I don't quite understand why you want to build a Weber kit, and replace the primary parts, xformers. Why not scratch build what you want?

    That said, the difference in volume from 20 to 15 watts is almost nothing. Why not just build it as spec'd and use an attenuator?
     
  3. Shea

    Shea Member

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    Plus, if you try to restrict your output power by deliberately undersizing the OT, you'll definitely have reduced bass response and maybe some splatty-sounding distortion too.

    Shea
     
  4. mr coffee

    mr coffee Gold Supporting Member

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    I have used their twin sized iron in a high power twin and it sounds killer
     
  5. bob-i

    bob-i Member

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    Honestly, you won't hear much difference in the power output. Running 6L6's and 6V6's at the same B+ voltage will only be 2-3 Db difference in power.

    You might think about a switch. You could lower the B+ a tad for the 6V6's.
     
  6. number9

    number9 Member

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    I agree with the other poster... if you are going to get a kit, then change the
    parts that make up 60% of the cost of the kit, why not build your own, or
    get someone to build you a kit with those parts already?

    Secondly, lowering the choke inductance will not lower headroom that much,
    if any, and you will end up with less bass, and less of other things you want.

    I suggest either a lower B+ switch, or triode mode switch, or change the front
    end plate resistors and cathode resistors to put it totally symmetric, but at a lower
    bias point for less gain. This will give you more control over headroom...

    Just my $0.02.
     
  7. sabby

    sabby Member

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    Thanks for the responses, all. As for the price of the kit, the speakers, cabinet, chassis account, and other sundry small parts account for almost all of it. The transformers are free if one buy the rest of the amp parts from Weber. What a deal. :cool:

    I already use an attenuator. I was only hoping to get a couple of amps in one box. Still, I'll be happy with one good one.
     
  8. Shea

    Shea Member

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    If I were you, I'd just build a normal tweed Pro or tweed super, and just swap between 6L6s (or some nice old-school 5881s) and 6V6s. That's what I do with a 5F8A twin clone I made. The volume drops just enough to make the difference between insanely friggin' loud and just really loud. Just make sure the 6V6s can handle the B+ voltage - when in doubt, use JJs.

    Shea
     

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