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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

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    ST-70 kit: 1000 hours+ later, now better than ever!


    Posts : 108
    Join date : 2008-12-09
    Location : BC, Canada

    ST-70 kit: 1000 hours+ later, now better than ever! Empty ST-70 kit: 1000 hours+ later, now better than ever!

    Post by JunkyJan Sun Jul 18, 2010 1:53 pm

    Hi Bob and all

    My ST-70 kit + VTA board I built last winter is running great and now actually seems to be sounding better! Having built it myself I was kind of worried that small issues relating to bad soldering joints etc might surface over time, however the amp is still dead-quiet and perfectly clean-sounding (no humming etc), the Gold Lion KT66 tubes are still running beautifully (I have seen some complaints on the guitar amp forums regarding the reliability of modern Gold Lion KT88 tubes, so I have been a bit suspicious - seems the KT66 variant is fine). I would guess that it has been running in excess of 1000 hours over the past 18 months and it has been a joy to listen to.

    I have discovered Triode mode (my kit had the Triode/Pentode switches), I initially did not really notice a difference between the two modes but lately realised that there are subtle difference - I think I actually prefer Triode operation for small Jazz ensembles and Classical music, when I go back into my Progressive and Industrial Rock mood, Pentode operation seems to sound better.

    Because of the success I had with this amplifier I am now a Dynaco "Fanboy", I am gearing up to build myself a pair of Mk. III monoblocks. Additionally, I am hoping to build the VTA preamplifier as well (I am still running my ST-70 in a "hybrid" configuration with a solid-state NAD 114 preamp - reason being that the NAD preamp has a VERY good sounding built-in moving coil phono amplifier).

    Best regards!
    -- JunkyJan in BC, Canada
    Bob Latino
    Bob Latino

    Posts : 3172
    Join date : 2008-11-26
    Location : Massachusetts

    ST-70 kit: 1000 hours+ later, now better than ever! Empty Re: ST-70 kit: 1000 hours+ later, now better than ever!

    Post by Bob Latino Mon Jul 19, 2010 6:11 pm

    Hi JunkyJan,

    Glad to hear that your VTA ST-70 kit is running well. Yes - the differences between triode and pentode are subtle and I think that your take on the two modes is accurate. Rock music is usually better in pentode but acoustic jazz and VOCALS sound really nice in triode.

    The Gold Lion KT66's are great in the ST-70 and the Gold Lion KT88's are great in the VTA ST-120 or Dynaco Mark III's. The only issue is the price. These are premium tubes and the prices are higher than most KT66 or KT88 tubes. I have had a quad of the Gold Lion KT88's in my ST-120 for about 2 years now with no issues. These tubes have maybe 2000 hours on them and still sound great. I tested them about a month ago and they still test near new.


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