Do I need to rebias my SF Deluxe reevrb.

Discussion in 'Amps and Cabs' started by squeally dan, Feb 8, 2008.


  1. squeally dan

    squeally dan Member

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    I've been using my Deluxe with a pair of 6L6's instead of 6V6's. I took it to a local tech for rebiasing when I made that change. Today I called him to let hin know that I might go back to the 6V6's and he said there was no need to rebias when doing so because it is silver face. Is this right? Don't I needto rebias it when going from 6L6's back to 6V6's?
     
  2. Blue Strat

    Blue Strat Member

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    You need to find a new tech.

    Yes, you must rebias for ANY power tube change.
     
  3. Top Geezer

    Top Geezer Member

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    I had the same situation on my SF DR. I took mine in for a service and the amp tech told me there was no bias pot on this amp (apparently some of the newer SF's were not made w/ a biasing pot), my amp tech added one so you could rebias the tubes correctly.

    Sounds like you need to add one too.
     
  4. Rosewood

    Rosewood Member

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    Boy that's weird unless he just let the 6l6's run with the 6v6 bias, nah, nobody would do that.
     
  5. squeally dan

    squeally dan Member

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    He said that when he put in the 6L6's he rebiased according to the directions I provided. But now he said changing back won't require a rebias. Looks like I need to try someone else.
     
  6. Blue Strat

    Blue Strat Member

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    I recommend getting yourself a bias probe and doing it yourself.
     
  7. slider313

    slider313 Silver Supporting Member

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    It may have had a balance bias, but it still would have some range of adjustment to an extent. If the tech couldn't find the bias pot.............
     
  8. Blue Strat

    Blue Strat Member

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    Deluxes never went to "bias balance" pots and every one of the 100s I've seen had a bias pot including late '70s versions, of which I own two.

    Even if an amp doesn't have a bias pot, you still have to bias it unless it's "cathode biased".
     
  9. squeally dan

    squeally dan Member

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  10. Blue Strat

    Blue Strat Member

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    Seriously, get a bias probe. That amp is VERY easy to bias. You don't even have to pull the chassis.
     
  11. squeally dan

    squeally dan Member

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    Ok. What type of probe woud you recommend? I've never done it but I'm all for learning how. I'm kinda sick of relying on other people to fix my stuff and wondering if they are doing it right? Can I figure out how to do it without watching someone else do it first?

    I actuallyly fixed my reverb pan this week by resodering a lose wire. Didn't know how to use one of those but I did it without killing myself. Maybe I can do this also.
     
  12. JDJ

    JDJ Supporting Member

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    Google Ted Weber speakers. Buy the Bias Rite.
     
  13. Blue Strat

    Blue Strat Member

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    www.tedweber.com Bias Rite or Google Bias King.

    There should be instructions. It's a bit mysterious the first time, but isn't everything? Definintely not rocket science and it will save you a lot of time dragging it to the tech.
     
  14. Dave

    Dave Member

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    There are easy to follow instructions on Ted's site. There's also a link to a bias calculator.

    :AOK
     
  15. squeally dan

    squeally dan Member

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    OK, I'm going to give it a a shot.

    Is it just as easy on a black face pro reverb?
     
  16. mcgriff420

    mcgriff420 Member

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    I just picked up this bias meter from Alessandro, the only concern I could forsee is if you have a tight tube location in a head format you might have to pull the chassis.

    [​IMG]
     
  17. Blue Strat

    Blue Strat Member

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    Yes, and the same for any black or silverface Fender with a bias pot (some Silver Faces have bias balance pots that would need to be converted).

    All '60s and '70s Fenders with bias pots are accessible from under or inside the chassis.
     
  18. squeally dan

    squeally dan Member

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  19. squeally dan

    squeally dan Member

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  20. squeally dan

    squeally dan Member

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    How do I locate the bias adjust trim pot?

    Sorry for all the questions.
     

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