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    5963 lasted 2749h

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    peterh

    Posts : 679
    Join date : 2012-12-25
    Location : gothenburg, sweden

    5963 lasted 2749h

    Post by peterh on Tue Oct 11, 2016 2:42 pm

    An uninteresting nerdy reports that noone really needs :

    When i started my vta-70 i installed an hour-meter.
    ( http://www.ebay.com/itm/Rectangle-LCD-Hour-meter-gauge-924-48-90-volt-golf-cart-forklift-9-80VDC-generic-/121052465515?hash=item1c2f4a096b )
    It currently shows 2749h.
    Today had to repace a 5963 due to ac-leaking from filament, detectable as
    a wining sound, overtones from dirty mains.

    So far a GZ34 has been replaced ( at app.900h ) 6550 and remaining 5962
    ticks on.

    And it still sounds wonderful , in fact there has been no change since it was new.

    Thanks Bob !

    10-E-C

    Posts : 87
    Join date : 2014-02-12
    Age : 63
    Location : upper east tn

    Re: 5963 lasted 2749h

    Post by 10-E-C on Tue Oct 11, 2016 8:54 pm

    peterh wrote:An uninteresting nerdy reports that noone really needs :

    When i started my vta-70 i installed an hour-meter.
    ( http://www.ebay.com/itm/Rectangle-LCD-Hour-meter-gauge-924-48-90-volt-golf-cart-forklift-9-80VDC-generic-/121052465515?hash=item1c2f4a096b )
    It currently shows 2749h.
    Today had to repace a 5963 due to ac-leaking from filament, detectable as
    a wining sound, overtones from dirty mains.

    So far a GZ34 has been replaced ( at app.900h ) 6550 and remaining 5962
    ticks on.

    And it still sounds wonderful , in fact there has been no change since it was new.

    Thanks Bob !

    I like the 5963 tubes, I have a pair of Phillips in my M125s and couldn't be happier.

    Kentley

    Posts : 335
    Join date : 2015-03-06
    Age : 64
    Location : Worcester, MA

    Re: 5963 lasted 2749h

    Post by Kentley on Tue Oct 11, 2016 9:48 pm

    Actually, Peter, I think this is very interesting. The only surprise here is the relative durability of your GZ-34s. Perhaps it is due to the more modest demands on that tube in the ST-70 - but still...so many of us struggle with our rectifiers in ST-120 and M-125 land.
    If my math is correct, at 4 hours per day (?!?!) you've been running relatively trouble-free for well over two years.
    One might expect that the time is coming for a new set of output tubes - hope you have as much luck with your next set.
    I've not had one 5963 blow on me in 20 months - I've rotated six or eight, and though some are less microphonic and noise-free than others, they are all as solid as Gibraltar. Great tubes. RCA and Sylvania alike.
    How's the incoming AC? I suspect it's nice and steady and clean.
    Keep up the yeoman work. We're counting on you for your steadfast input, which is both joyous and insightful.

    Bob Latino
    Admin

    Posts : 2411
    Join date : 2008-11-26
    Location : Massachusetts

    Re: 5963 lasted 2749h

    Post by Bob Latino on Wed Oct 12, 2016 8:41 am

    5963, 5814 and 6189 tubes are military/industrial versions of a 12AU7. They were made primarily for the US military but were also used in industrial test gear in the 1960's and 1970's. They were made primarily by GE, RCA and Sylvania and (IMHO) are better than most currently made 12AU7 driver tubes .. I have a good stock of these tubes and ship them as driver tubes for all customers that want a tube set with their VTA amp kit. If you go out there and look for these on Ebay or other web sites that sell tubes, the 5963 versions tend to be a little less costly than 5814 or 6189 versions but I find no real advantage of one over the other. IMHO all three are of equal quality and getting 5000+ hours out of these is fairly normal. Yep .. Every now and then you might get a noisy or microphonic piece but as a class, these tend to be less noisy/microphonic than other types of tubes like the 6DJ8/6922 type tubes. The British military version of this tube is the Mullard CV4003. The Mullard CV4003 tubes, however, are getting very pricey .. If you can find a CV4003 under $50, you are doing good.

    Bob

    peterh

    Posts : 679
    Join date : 2012-12-25
    Location : gothenburg, sweden

    Re: 5963 lasted 2749h

    Post by peterh on Wed Oct 12, 2016 8:58 am

    I have no problem that one 5963 did not reach 5000h, i find it quite normal that some will last longer and som shorter.
    This particular one has developed both a "filament-to-cathode leak" and i also discovered that it
    has developed micronophony. This can happen with any tubes. My contribution is the use of a
    hours meter which makes it possible to get accurate figures instead of estimated guesses.
    For symmetry reasons i also changed the other driver tube, also to a JJ ecc82. The central amp-tube
    is still there ( and will so until it breaks )

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    Re: 5963 lasted 2749h

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