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    Weird KT66 problems...

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    Corona

    Posts: 32
    Join date: 2010-03-11

    Weird KT66 problems...

    Post by Corona on Mon May 10, 2010 11:15 pm

    So after reading all of the praise on the BNB kt66 gold lion tubes I decided to get a quad of them to use in my st70. Got them today and gave them a go. They biased alright and I set them all to 430-440 to start with. I left the amp playing for a while and didn't notice any problems. When I turned out the lights to look at them in the dark I noticed some rather strange things.
    1-The plates were glowing dull red in some areas Shocked This is only noticeable in the dark. The KT88's I have only glow like that if the bias is set to something crazy like 900+ on that one tube.
    2-Looking through the plates of the tubes there are some weird blueish purple streaks between the plates or something. At higher bias like 450+ they put out a noticeable amount of light from the tubes. These are NOT like the blue glow from the glass on my sovtek kt88's from electrons hitting the glass in areas.

    I promptly turned the bias all the way down to 380-390 per tube and the plates were still glowing dull red in the dark. Tried switching it to triode mode to further reduce the the power to the tubes. Still glowing red.

    It actually plays music alright, but at idle with the preamp turned off one channel has a noticeably louder buzz or some kind of noise. With the kt88's back in they're both extremely quite at idle.

    Also the power transformer is getting hot ?faster? than with the kt88's. Surely something is wrong here.

    thevic24

    Posts: 29
    Join date: 2010-01-31

    Re: Weird KT66 problems...

    Post by thevic24 on Tue May 11, 2010 5:17 pm

    Sounds to me like you may have a bad tube or tubes. Are they all glowing red?

    Sometimes if a tube gets bounced hard enough during shipping it can knock the plates and what not out of alignment causing your problem.


    -Vic

    Corona

    Posts: 32
    Join date: 2010-03-11

    Re: Weird KT66 problems...

    Post by Corona on Tue May 11, 2010 5:48 pm

    thevic24 wrote:Sounds to me like you may have a bad tube or tubes. Are they all glowing red?

    Sometimes if a tube gets bounced hard enough during shipping it can knock the plates and what not out of alignment causing your problem.


    -Vic
    Well if it was only one of the tubes I could see that. All 4 have glowing plates though and the bias is only set at like .390-.400 per tube.

    Is this just normal for the gold lion kt66 tubes? It's not like they're glowing brightly or anything. The room has to be dark just to notice the plates glowing dull red in a few areas. Anyone else have them and can comment on this?

    avi.inc

    Posts: 53
    Join date: 2009-08-03
    Age: 61
    Location: L.A.

    Re: Weird KT66 problems...

    Post by avi.inc on Tue May 11, 2010 7:56 pm

    Can you post a pik of how it looks?

      Current date/time is Sun Oct 26, 2014 12:53 am