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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 products

    Tube life in ST-120


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

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

    Post by davek65 on 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 .
    Bob Latino
    Bob Latino

    Posts : 2916
    Join date : 2008-11-26
    Location : Massachusetts

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

    Post by Bob Latino on 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 $$$.


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