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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


    gz34 vs 5y3 vs 5u4

    rfbro
    rfbro

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    gz34 vs 5y3 vs 5u4 Empty gz34 vs 5y3 vs 5u4

    Post by rfbro on Sat May 21, 2016 10:09 pm

    Wondering if it is ok to use a 5y3 or 5u4 in place of a 5ar4 in my ST 120
    Tubes4ever
    Tubes4ever

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    Post by Tubes4ever on Sun May 22, 2016 1:15 am

    rfbro wrote:Wondering if it is ok to use a 5y3 or 5u4 in place of a 5ar4 in my ST 120

    You can't use a 5y3 since it is rated at 125mA max. You can use a 5u4GB as it is rated at 275mA. The recommended bias setting for the ST120 tubes is 50 mA each for a total of 200mA plus about 25mA for the VTA board. The 5U4 will work just fine.
    Bob Latino
    Bob Latino
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    Post by Bob Latino on Sun May 22, 2016 7:55 am

    gz34 vs 5y3 vs 5u4 5voltrectifiertubes
    This chart has been posted before .. You can probably use any of the rectifiers that are 250 milliamp (or higher) rated (MaxPma). All the VTA amps have 4 amp rated 5 volt rectifier filament lines (Famp) so any rectifier rated below 4 amps current draw will work as long as the MaxPma is 250 milliamps or higher.

    Bob


    Last edited by Bob Latino on Sun May 22, 2016 11:09 am; edited 2 times in total
    Tubes4ever
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    Post by Tubes4ever on Sun May 22, 2016 11:00 am

    Bob,

    This should be a sticky. Except change "5 volts bias lines" to 5 volt heater windings.

    Tim
    Bob Latino
    Bob Latino
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    Post by Bob Latino on Sun May 22, 2016 11:14 am

    Tubes4ever wrote:Bob,

    This should be a sticky.  Except change "5 volts bias lines" to 5 volt heater windings.

    Tim

    Hi Tim,

    Thanks for pointing out ... I made an appropriate change in the text of that post .. Don't know why I said "bias" line. The bias line is 55 VAC .. That would sure make that rectifier light up pretty bright but > for a very short time - lol ..

    Bob

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    tubes4hifi
    tubes4hifi
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    Post by tubes4hifi on Sun May 22, 2016 12:17 pm

    Bob & all,
    here's an edited version of the list, only tubes with 250ma or better, and only 8 pin tubes . . .
    gz34 vs 5y3 vs 5u4 5vRectifier
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    Tom

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    Post by Tom on Sat Jun 27, 2020 3:50 pm

    All the alternatives have a much higher voltage drop than the GZ34.

    Anyone knowledgeable about any issues there?
    peterh
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    Post by peterh on Sat Jun 27, 2020 3:58 pm

    Tom wrote:All the alternatives have a much higher voltage drop than the GZ34.

    Anyone knowledgeable about any issues there?
    What "issue" ??

    GZ34 is the recommended tube... And there is no shortage as this is
    a tube in current production from several sources.
    PeterCapo
    PeterCapo

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    Post by PeterCapo on Sat Jun 27, 2020 4:55 pm

    Tom wrote:All the alternatives have a much higher voltage drop than the GZ34.

    Anyone knowledgeable about any issues there?

    A greater voltage drop means the amplifier will make less power. How much less I cannot specifically say. You'd have to get it on a bench and take some measurements. But it will make less power.
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    Tom

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    Post by Tom on Sat Jun 27, 2020 8:31 pm

    Thanks Peter C.
    Peterh, was pricing NOS tubes and some of the alternative tubes are 10% to 20% cost of a NOS mullard GZ34. Was curious why.

    Sponsored content

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