The Dynaco Tube Audio Forum

Would you like to react to this message? Create an account in a few clicks or log in to continue.
The Dynaco Tube Audio Forum

Dedicated to the restoration and preservation of all original Dynaco tube audio equipment - Customer support for Tubes4hifi VTA tube amp and preamp kits and all Dynakitparts.com products


3 posters

    VTA ST120 kt88

    rfbro
    rfbro


    Posts : 27
    Join date : 2014-12-28
    Age : 68
    Location : Vancouver WA

    VTA ST120 kt88 Empty VTA ST120 kt88

    Post by rfbro Thu Jul 18, 2019 4:19 pm

    When I turn my preamp off when the amp is still on my right rear PT 88 has a slight blue glow to it for a second could that be the bias resistor if so what is the value of the Bias resistor
    peterh
    peterh


    Posts : 1823
    Join date : 2012-12-25
    Location : gothenburg, sweden

    VTA ST120 kt88 Empty Re: VTA ST120 kt88

    Post by peterh Thu Jul 18, 2019 4:35 pm

    rfbro wrote:When I turn my preamp off when  the amp is still on my right rear PT 88 has a slight blue glow to it for a second could that be the bias resistor if so what is the value of the Bias resistor
    It's nothing wrong with the vta120, it's a procedural error !
    The vta120 will get a surge when the pre is turned off. This might be damaging to the tubes and should be avoided.
    Better turn the vta120 off first , then after a few seconds the pre.

    At power on, turn the pre on first, and after a while ( 30s ?) turn the vta120 on.
    deepee99
    deepee99


    Posts : 2244
    Join date : 2012-05-23
    Location : Wallace, Idaho

    VTA ST120 kt88 Empty Re: VTA ST120 kt88

    Post by deepee99 Fri Jul 26, 2019 11:36 am

    peterh wrote:
    rfbro wrote:When I turn my preamp off when  the amp is still on my right rear PT 88 has a slight blue glow to it for a second could that be the bias resistor if so what is the value of the Bias resistor
    It's nothing wrong with the vta120, it's a procedural error !
    The vta120 will get a surge when the pre is turned off. This might be damaging to the tubes and should be avoided.
    Better turn the vta120 off first , then after a few seconds the pre.

    At power on, turn the pre on first, and after a while ( 30s ?) turn the vta120 on.

    Yeah. What Peterh said.
    deepee99
    deepee99


    Posts : 2244
    Join date : 2012-05-23
    Location : Wallace, Idaho

    VTA ST120 kt88 Empty Re: VTA ST120 kt88

    Post by deepee99 Fri Jul 26, 2019 11:38 am

    Oops, posted the following twice

    Sponsored content


    VTA ST120 kt88 Empty Re: VTA ST120 kt88

    Post by Sponsored content


      Current date/time is Fri Mar 29, 2024 1:28 am