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    6550 bias?

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    jhoak

    Posts : 46
    Join date : 2009-10-16
    Age : 58
    Location : Central Florida

    6550 bias?

    Post by jhoak on Sun Sep 25, 2011 6:52 pm

    Next week a buddy of mine is bringing me a matched quad of Winged C 6550s for me to check out in my ST-120. Very Happy

    Should I bias them any differently than my KT88s or KT120s?

    I wouldn't think so but thought I should probably ask rather than blow up about $200 worth of tubes that I don't own.

    THANX!
    jhoak

    Westy56

    Posts : 58
    Join date : 2011-05-09
    Location : Albuquerque

    Re: 6550 bias?

    Post by Westy56 on Sun Sep 25, 2011 9:03 pm

    jhoak wrote:Next week a buddy of mine is bringing me a matched quad of Winged C 6550s for me to check out in my ST-120. Very Happy

    Should I bias them any differently than my KT88s or KT120s?

    I wouldn't think so but thought I should probably ask rather than blow up about $200 worth of tubes that I don't own.

    THANX!
    jhoak

    I can't speak for the 120's, but you could probably run the 6550 10-15 milliamps less than the kt88 with good results.
    This will help extend the life without degradation to the sound.

    They will probably bias differently as far as where your adjustment pot setting are turned compared to the kt88.



    Steve

    Bob Latino
    Admin

    Posts : 2376
    Join date : 2008-11-26
    Location : Massachusetts

    Re: 6550 bias?

    Post by Bob Latino on Sun Sep 25, 2011 10:21 pm

    6550 tubes are not a "strong" a tube in handling high voltage as a KT88 or KT120. I have used them here before in a VTA ST-120. Personally, I just bias them the same as a KT88. Dave has a good point though in that maybe in the VTA ST-120 the bias should be dropped a little when using 6550 output tubes. Anytime you can operate an output tube at a lower bias level, the tube will last longer.

    Bob

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