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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


3 posters

    Speaker terminal wiring for VTA70 upgrade

    erniegiro
    erniegiro
    erniegiro


    Posts : 22
    Join date : 2020-08-07
    Location : Atlanta, GA USA
    • Post n°1

    Speaker terminal wiring for VTA70 upgrade Empty Speaker terminal wiring for VTA70 upgrade

    Post by erniegiro Wed Oct 28, 2020 1:18 am

    I've looked at the wiring diagrams for the speaker terminals for the VTA70 upgrade, and as I'm about to undertake the installation
    I'm a bit confused as to what to do with the unused wires and specifically where to attach the wire that goes to the NFB eyelet on the new PCB.

    I intend to use one of the 3 binding post kits, with a common and 2 hot binding posts.

    I intend to only connect taps that go to the 4 & 8 ohm taps - the brown and orange wires, and the common tap - black wire, and roll up the 16 ohm yellow wire so it does not accidentally contact the chassis.

    Does the wire that goes to the NFB eyelet now go to one of the speaker taps in use?

    Thanks in advance for your comments!
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    Bob Latino
    Bob Latino
    Bob Latino
    Admin


    Posts : 3263
    Join date : 2008-11-26
    Location : Massachusetts
    • Post n°2

    Speaker terminal wiring for VTA70 upgrade Empty Re: Speaker terminal wiring for VTA70 upgrade

    Post by Bob Latino Wed Oct 28, 2020 8:32 am

    erniegiro wrote:I've looked at the wiring diagrams for the speaker terminals for the VTA70 upgrade, and as I'm about to undertake the installation
    I'm a bit confused as to what to do with the unused wires and specifically where to attach the wire that goes to the NFB eyelet on the new PCB.

    I intend to use one of the 3 binding post kits, with a common and 2 hot binding posts.

    I intend to only connect taps that go to the 4 & 8 ohm taps - the brown and orange wires, and the common tap - black wire, and roll up the 16 ohm yellow wire so it does not accidentally contact the chassis.

    Does the wire that goes to the NFB eyelet now go to one of the speaker taps in use?

    Thanks in advance for your comments!

    On the original Dynaco ST-70 amps the YELLOW 16 ohm wire went to the 16 ohm terminal on the output speaker strip and then a wire went from the 16 ohm terminal on the speaker terminal strip to the NFB eyelets on the PC-3 driver board (eyelet 12 for the left channel and eyelet 13 for the right channel). On the VTA version of the ST-70 there are 4 and 8 ohm taps so what you can do is to just run the YELLOW 16 ohm wire on each channel directly to the the NFB eyelets on the driver board.

    Bob

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    erniegiro
    erniegiro
    erniegiro


    Posts : 22
    Join date : 2020-08-07
    Location : Atlanta, GA USA
    • Post n°3

    Speaker terminal wiring for VTA70 upgrade Empty Re: Speaker terminal wiring for VTA70 upgrade

    Post by erniegiro Wed Oct 28, 2020 11:18 am

    Bob, thanks for the reply, that makes things clearer!
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    Cl75
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    Cl75


    Posts : 23
    Join date : 2021-07-27
    • Post n°4

    Speaker terminal wiring for VTA70 upgrade Empty Re: Speaker terminal wiring for VTA70 upgrade

    Post by Cl75 Wed Jul 28, 2021 12:06 am

    Hi Bob.I'm about to purchase 2nd hand dynaco st70 with vta moded. There are only 1 red and 1 black at 2 pairs of binding posts. I have 2 sets of speakers 4ohm and 8 ohm. What do I need to do if I want to swap out speakers? I'm a novice in audio equipment, please forgive me if my question is not clear or make sense. Thank you very much.
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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°5

    Speaker terminal wiring for VTA70 upgrade Empty Re: Speaker terminal wiring for VTA70 upgrade

    Post by Bob Latino Wed Jul 28, 2021 8:15 am

    Cl75 wrote:Hi Bob.I'm about to purchase 2nd hand dynaco st70 with vta moded. There are only 1 red and 1 black at 2 pairs of binding posts. I have 2 sets of speakers 4ohm and 8 ohm. What do I need to do if I want to swap out speakers? I'm a novice in audio equipment, please forgive me if my question is not clear or make sense. Thank you very much.

    We do sell 3 post binding posts for the Dynaco ST-70 on the web page below. They are about 1/2 way down on the right. See photo and link below.

    Bob

    Tubes4hifi ST-70 page


    Speaker terminal wiring for VTA70 upgrade TripleSpr-96
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    • Post n°6

    Speaker terminal wiring for VTA70 upgrade Empty Re: Speaker terminal wiring for VTA70 upgrade

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