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    Another KT88 VTA ST 70 question

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    Dave_in_Va

    Posts : 129
    Join date : 2013-04-02

    Another KT88 VTA ST 70 question

    Post by Dave_in_Va on Mon Dec 30, 2013 11:27 am

    This is similar to another question below but I didn't want to hijack the thread as it refers to slightly different amp.

    I have what was supposed* to be a matched set of Psvane KT 88's in my VTA ST 70. I have three of the tubes biased at 49-50 mA but one refuses to go that low. It sometimes sits at around 55 and this morning is reading 64mA.

    The amp sounds great. Should I worry about this? I have a couple of sets of EL34's I could use but I have to admit the 88's look really cool. Also, the system sounds better now but I also have a feeling my system is just breaking in.

    * Too late to return. To Hong Kong.

    EDIT: I forgot to add that I tried squeezing in the pins the pins on this socket.


    Last edited by Dave_in_Va on Mon Dec 30, 2013 9:17 pm; edited 1 time in total (Reason for editing : Additional info.)

    peterh

    Posts : 642
    Join date : 2012-12-25
    Location : gothenburg, sweden

    Re: Another KT88 VTA ST 70 question

    Post by peterh on Mon Dec 30, 2013 12:50 pm

    Dave_in_Va wrote:This is similar to another question below but I didn't want to hijack the thread as it refers to slightly different amp.

    I have what was supposed* to be a matched set of Psvane KT 88's in my VTA ST 70. I have three of the tubes biased at 49-50 mA but one refuses to go that low. It sometimes sits at around 55 and this morning is reading 64mA.

    The amp sounds great. Should I worry about this? I have a couple of sets of EL34's I could use but I have to admit the 88's look really cool. Also, the system sounds better now but I also have a feeling my system is just breaking in.

    * Too late to return.
    An unstable tube should be replaced. Something is wrong with it.
    If your tube vendor has been kind enough to label the tubes with bias info, then he could send another matching tube to you.

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