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    Against my religion, but . . .

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    deepee99

    Posts : 1260
    Join date : 2012-05-23
    Location : Wallace, Idaho

    Against my religion, but . . .

    Post by deepee99 on Sat May 24, 2014 4:53 pm

    I just tweaked the bias on the new KT-120s up a bit, to about 65/tube (1.3v on the meter) and indeed the sound opens up quite a bit at both ends. Wonder what this would to to tube life?

    Bob Latino
    Admin

    Posts : 2378
    Join date : 2008-11-26
    Location : Massachusetts

    Re: Against my religion, but . . .

    Post by Bob Latino on Sat May 24, 2014 5:33 pm

    The higher you bias the amp, the longer the M-125 amp stays in Class A before switching over to class AB1. This does have a subtle effect on the sound of the amp - usually for the better - BUT - as you well know > the higher the bias the shorter the tube life and the higher the bias the more current the amp uses and the more heat the amp produces. I have run the bias on my own M-125's up to 75 milliamps per tube. The amps ran noticeably hotter and sounded fine - BUT - I do not recommend doing this. It puts a strain on the power transformer and the rectifier has to work harder also.

    Bob

    deepee99

    Posts : 1260
    Join date : 2012-05-23
    Location : Wallace, Idaho

    Re: Against my religion, but . . .

    Post by deepee99 on Sat May 24, 2014 5:53 pm

    Bob Latino wrote:The higher you bias the amp, the longer the M-125 amp stays in Class A before switching over to class AB1. This does have a subtle effect on the sound of the amp - usually for the better - BUT - as you well know > the higher the bias the shorter the tube life and the higher the bias the more current the amp uses and the more heat the amp produces. I have run the bias on my own M-125's up to 75 milliamps per tube. The amps ran noticeably hotter and sounded fine - BUT - I do not recommend doing this. It puts a strain on the power transformer and the rectifier has to work harder also.

    Bob

    Well, I'll try .65 for awhile, see if it's worth it. I just checked the xformers and they're warm to the touch but not hot, about the same as .6.
    I believe I read that sKiZo runs his at about two volts, but then again, we haven't heard from him for a while. Perhaps there is a smoking black hole. This would not be good.

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