The Dynaco Tube Audio Forum

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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


2 posters

    Tube life in ST-120

    davek65
    davek65


    Posts : 15
    Join date : 2011-01-22
    Location : Pittsburgh

    Tube life in ST-120 Empty Tube life in ST-120

    Post by davek65 Wed Aug 10, 2011 2:04 pm

    When i built the ST-120 i also purchased an Hour meter to keep track of tube life and
    just overall use of the amp . As the time of over 1000 hours has been logged 2 of the
    original set of Gold Lion KT88's i installed have lived their life . 1 last week and 1 today .

    Both ended with grid shorts . I replaced the fuse with a 4 amp mini breaker i purchased through
    Webber that makes the Copper Rectifiers . It mounts through the hole where the original fuse
    holder was . It's just more convenient than using a regular fuse . My amp is on a permanent
    wall shelf in the basement where it's nice and cool and plenty of air around it . It's
    the place of many past amps .

    So my finding it that the average power tube life is around 1000 + hours per tube .
    Whats your take on this .
    Dave
    Bob Latino
    Bob Latino
    Admin


    Posts : 3258
    Join date : 2008-11-26
    Location : Massachusetts

    Tube life in ST-120 Empty Re: Tube life in ST-120

    Post by Bob Latino Wed Aug 10, 2011 2:47 pm

    Hi Dave,

    Output tubes such as KT88's SHOULD have an average useful life of maybe 2000 to 3000 hours. Sad to say that the tubes made now in Russia, China and the Slovak Republic just don't seem to last as long as those made in the USA, Great Britain and Germany in the 1950's and 1960's. The quality control, the materials and the manufacturing process were undoubtedly better in days gone by. This is the reason you see NOS Mullard GZ34's going for $150+ and NOS Tung-Sol, Genalex, Telefunken, Siemans etc. tubes going for big $$$.

    Bob

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