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    KT-66 question

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    cc43fan

    Posts : 29
    Join date : 2012-01-30
    Age : 53
    Location : Upstate New York

    KT-66 question

    Post by cc43fan on Sun Apr 01, 2012 10:46 am

    I've completed my ST-70 restore, and the amp has about 20 hours on it using EL-34's. It's been rock solid, no hum, buzzing, and bias has stayed spot on. Last night I put KT-66's in the amp, and as soon as it warmed up, the KT-66's flashed bright light at or near the getter and a crackle sound came from the right channel. I instantly shut it down. I put the EL-34's back in and all was fine. I'm using the SDS power supply and VTA driver board. I have a 12AU7 in the center position and 12BH7's on the outside. The KT-66's I purchased are used, and I assumed were good.
    I shut it down as soon as I saw the flash and heard the crackle, but I have no experence with this tube so I don't know if that's "normal", but I'm guessing it's not.

    Can anyone shed some light on what I experenced, any thoughts on what is wrong (if anything), and possible solutions?

    Thanks,
    Chuck

    Tube Nube

    Posts : 603
    Join date : 2008-12-06
    Age : 53
    Location : Calgary, AB

    Re: KT-66 question

    Post by Tube Nube on Sun Apr 01, 2012 11:05 am

    All of them flashed? Are they Mullards?

    cc43fan

    Posts : 29
    Join date : 2012-01-30
    Age : 53
    Location : Upstate New York

    Re: KT-66 question

    Post by cc43fan on Sun Apr 01, 2012 11:14 am

    Tube Nube wrote:All of them flashed? Are they Mullards?

    Only the right channel flashed. I turned it off quickly so I think I didn't give the left channel to flash (or I didn't see it). The tubes are valve art.

    Tube Nube

    Posts : 603
    Join date : 2008-12-06
    Age : 53
    Location : Calgary, AB

    Re: KT-66 question

    Post by Tube Nube on Sun Apr 01, 2012 6:13 pm

    Darn. I thought if they were Mullards, then you'd have your explanation. They flash brighter when they first come on, then settle down.

    cc43fan

    Posts : 29
    Join date : 2012-01-30
    Age : 53
    Location : Upstate New York

    Re: KT-66 question

    Post by cc43fan on Wed Apr 04, 2012 10:26 am

    I solved it. Thanks to those who offered help.

    Alan-14

    Posts : 46
    Join date : 2012-03-31
    Age : 56
    Location : Melbourne - Australia

    Re: KT-66 question

    Post by Alan-14 on Thu Apr 05, 2012 5:35 pm

    What was the problem?

    cc43fan

    Posts : 29
    Join date : 2012-01-30
    Age : 53
    Location : Upstate New York

    Re: KT-66 question

    Post by cc43fan on Thu Apr 05, 2012 7:30 pm

    Alan-14 wrote:What was the problem?

    Tube was bad.

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