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OT Primary question

Discussion in 'Amp Tech Center' started by DucDone, Jan 13, 2021.

  1. DucDone

    DucDone Tele-Meister

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    Hi. I have a question about the two primaries on my Hammond 1650t shown in the pic. Could anyone explain the use of the two extras here? (Screen grid tap?) Other than plate/B+?
     

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  2. Jon Snell

    Jon Snell Tele-Holic

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    Wally likes this.
  3. Squawker

    Squawker Tele-Holic

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    The "extras" can be tied to the screen grids when running in ultra-linear mode (UL). It's generally a hifi thing, but I believe some bass amps do it too.

    It's something in between running in normal pentode mode, and strapping a pentode into triode mode (including beam-tetrodes under the general category of pentodes :p) The Hifi guys will tell you that triodes offer the best sound reproduction, but UL will give you more power and possibly suit rock music better, without going to the "extreme harmonic distortion" of pentodes. In the guitar world we like harmonic distortion :)
     
  4. DucDone

    DucDone Tele-Meister

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    So in a tube amp, what should I do with it?
     
  5. Jon Snell

    Jon Snell Tele-Holic

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    Anodes to the 'P' connections. Screen grids either to conventional HT or to SG connections. Some switch in either for a choice of Pentode mode, (Screen grids to HT) and Ultra Linear Mode (Screen grids to tappings , usually at 43% of winding).
    UL will produce more power, (Fender style, full bluesy and clean) Pentode (more gain and more second harmonic distortion). The choice is purely yours.
     
  6. DucDone

    DucDone Tele-Meister

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    Could I omit them, that is not using them?
     
  7. Squawker

    Squawker Tele-Holic

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    Yes. Shrink wrap the ends and coil. Fasten with a cable strip.

    You can cut them short if you know for sure that the OT will never be reused in an UL design - your choice.
     
  8. DucDone

    DucDone Tele-Meister

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    Thanks.
     
  9. timfred

    timfred Tele-Meister

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    If your amp has NFB, you might want to try the OT in UL configuration but with NFB disconnected. UL is a type of feedback, and together with NFB it can be sterile but by itself it might be a great sound for you.
     
  10. Wally

    Wally Telefied Ad Free Member

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    There are guitar amps other than the SF Fender UL amps from 1977-1981 that utilize Ultralinear outputs. The famed Dr. Z Carmen Ghia for one The Carmen Ghia amp was built on the basis of the Hammond AO35 reverb amplifier. Dr Z’s Rt. 66 is another that uses UL output.
     
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