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


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Jim McShane
danskman
tTube
j beede
GP49
Bob Latino
frank
baddog1946
erlingt
edgobb
xlr8
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    6p3s-e report

    frank
    frank
    frank


    Posts : 97
    Join date : 2011-02-14
    Location : Pacific Northwest
    • Post n°26

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    Post by frank Sun Dec 22, 2013 11:43 pm

    xlr8 wrote:I hear supplies might be drying up, which is unfortunate. Thankfully, I think I acquired enough early on to last me the rest of my life, so I'll let you guys fight over/pay for the leftovers lol!!

    This truly is a shame. I only have the 8 tubes originally purchased. Wish I had more.
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    allenmmusic10003
    allenmmusic10003
    allenmmusic10003


    Posts : 14
    Join date : 2013-08-24
    • Post n°27

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    Post by allenmmusic10003 Mon Dec 23, 2013 9:21 pm

    While browsing the inventories of eBay sellers that carry this tube, I ran across the 6N2P-EV (billed as a 12AX7 equivalent). Anyone heard of or had any experience with them?

    They're affordable. Thus, my optimism is tempered.

    Merry Christmas
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    Bob Latino
    Bob Latino
    Bob Latino
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    Posts : 3263
    Join date : 2008-11-26
    Location : Massachusetts
    • Post n°28

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    Post by Bob Latino Mon Dec 23, 2013 9:32 pm

    fswidecki wrote:
    deluxmon wrote:This is an new question posted in an older string.....I see Bob's suggestion of biasing the Russian  6p3s-e tubes at 40 to 50 milliamps per tube. Would this mean that one could bias these tubes at
    .400 -.500 VDC?
    ...Pete

    Nope, please go back and reread that post. Unless your amp has characteristics with which I am not familiar, the bias should be between 1.248v and 1.56v per PAIR of output tubes. That would be between 0.624v (haha) and 0.78v per tube.

    'Frank

    Frank,

    What happens is this .. Dynaco used a 15.6 ohm bias resistor not a 10 ohm bias resistor on the original ST-70 - SO - the 1.56 bias voltage on a STOCK ST-70 equates to 100 milliamps per PAIR OR 50 milliamps per EACH output tube. Using the 1.248 bias voltage with a single 15.6 ohm bias resistor equates to 80 milliamps per each output tube PAIR or 40 milliamps per each output tube.

    The VTA amps use a 10 ohm bias resistor - SO - .400 VDC on an ST-70 equates to 40 milliamps per each output tube.

    Bob
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    frank
    frank
    frank


    Posts : 97
    Join date : 2011-02-14
    Location : Pacific Northwest
    • Post n°29

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    Post by frank Tue Dec 24, 2013 3:05 am

    Oops, sorry. Your way is simpler/better. Thanks for the correction.

    Would it be possible/practical to swap out my bias resistors for 10ohm ones? Makes more sense to me. I've yet to compare my bias to a dry-cell battery.


    Last edited by fswidecki on Tue Dec 24, 2013 3:11 am; edited 1 time in total (Reason for editing : Added question)
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