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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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Maintarget
Analog Man
6 posters

    VTA ST - 120 Finished and up and running!!!

    Analog Man
    Analog Man
    Analog Man


    Posts : 56
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    • Post n°1

    VTA ST - 120 Finished and up and running!!! Empty VTA ST - 120 Finished and up and running!!!

    Post by Analog Man Sat Sep 21, 2013 1:34 pm

    How sweet it is! This baby sounds awesome, Better than my A500 reference amplifiers. Especially good bass, organ, vocals, ect.
    I seem to prefer the sound of the JJ ECC 802S driver tubes as opposed to the Electro harmonix 12BH7A's
    See link for pics.

    https://s756.photobucket.com/user/hilldwellerstl/library/?sort=3&page=1
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    Maintarget
    Maintarget
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    • Post n°2

    VTA ST - 120 Finished and up and running!!! Empty Re: VTA ST - 120 Finished and up and running!!!

    Post by Maintarget Sat Sep 21, 2013 2:03 pm

    Wow looks nice great to hear
    I had a few (Self inflicted) start up issues that I have sorted out, wife picking up new rectifier tube while I'm stuck at work hopefully tonight I'll be groven on some sweet sound myself!
    Enjoy!
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    Analog Man
    Analog Man
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    • Post n°3

    VTA ST - 120 Finished and up and running!!! Empty Re: VTA ST - 120 Finished and up and running!!!

    Post by Analog Man Sat Sep 21, 2013 2:11 pm

    Maintarget wrote:Wow looks nice great to hear
    I had a few (Self inflicted) start up issues that I have sorted out, wife picking up new rectifier tube while I'm stuck at work hopefully tonight I'll be groven on some sweet sound myself!
    Enjoy!
    Great! Let us know how it comes out. You must be excited.
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    Zimmer64
    Zimmer64
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    • Post n°4

    VTA ST - 120 Finished and up and running!!! Empty Re: VTA ST - 120 Finished and up and running!!!

    Post by Zimmer64 Sat Sep 21, 2013 2:41 pm

    Nice build ! Congratulations and enjoy.
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    Bob Latino
    Bob Latino
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    • Post n°5

    VTA ST - 120 Finished and up and running!!! Empty Re: VTA ST - 120 Finished and up and running!!!

    Post by Bob Latino Sat Sep 21, 2013 4:45 pm

    Analog Man wrote:How sweet it is! This baby sounds awesome, Better than my A500 reference amplifiers. Especially good bass, organ, vocals, ect.
    I seem to prefer the sound of the JJ ECC 802S driver tubes as opposed to the Electro harmonix 12BH7A's
    See link for pics.

    https://s756.photobucket.com/user/hilldwellerstl/library/?sort=3&page=1
    Hi James,

     All the VTA amps really respond well to tube changes .. Especially the center driver tube on VTA ST-70's and VTA ST-120's and the front driver tube on the M-125 monoblocks. It is really not possible to say that any one 12AU7/12BH7 driver tube is a lot better than any other. The reason being that with certain speakers, certain tube types will shine. In the VTA amps you can also use as driver tubes (beside 12AU7/12BH7) 5814, 5963, 6189 and the Mullard made CV4003. There are plenty of USA made 5814, 5963 and 6189 tubes still in circulation that are great sounding tubes in these amps ..

    Bob
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    Analog Man
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    • Post n°6

    VTA ST - 120 Finished and up and running!!! Empty Re: VTA ST - 120 Finished and up and running!!!

    Post by Analog Man Sat Sep 21, 2013 4:55 pm

    Thanks, nice to know.
    I have only one N.O.S. GE 12BH7A. Would it be worth while to put this in the center of the driver board and then the new EH 12BH7A's on the sides?
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    sKiZo
    sKiZo
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    • Post n°7

    VTA ST - 120 Finished and up and running!!! Empty Re: VTA ST - 120 Finished and up and running!!!

    Post by sKiZo Sat Sep 21, 2013 6:26 pm

    Nice!

    So what do you think of those big bottle KT120's?
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    Analog Man
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    • Post n°8

    VTA ST - 120 Finished and up and running!!! Empty Re: VTA ST - 120 Finished and up and running!!!

    Post by Analog Man Sat Sep 21, 2013 7:00 pm

    sKiZo wrote:Nice!

    So what do you think of those big bottle KT120's?
    I love them! Plenty of power and freq. response. Very stable, tough well made tube.Smile 
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    Bob Latino
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    • Post n°9

    VTA ST - 120 Finished and up and running!!! Empty Re: VTA ST - 120 Finished and up and running!!!

    Post by Bob Latino Sat Sep 21, 2013 7:01 pm

    Analog Man wrote:Thanks, nice to know.
    I have only one N.O.S.  GE 12BH7A. Would it be worth while to put this in the center of the driver board and then the new EH 12BH7A's on the sides?
    Yes - It would be worth a try .. The center (voltage amplifier) tube has more influence on the sound of the amp than the two side (phase splitter/inverter) tubes ..

    Bob
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    Analog Man
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    • Post n°10

    VTA ST - 120 Finished and up and running!!! Empty Re: VTA ST - 120 Finished and up and running!!!

    Post by Analog Man Sat Sep 21, 2013 7:05 pm

    Bob Latino wrote:
    Analog Man wrote:Thanks, nice to know.
    I have only one N.O.S.  GE 12BH7A. Would it be worth while to put this in the center of the driver board and then the new EH 12BH7A's on the sides?
    Yes - It would be worth a try .. The center (voltage amplifier) tube has more influence on the sound of the amp than the two side (phase splitter/inverter) tubes ..

    Bob
    Thanks! I also found that I have some N.O.S. JAN 5814 , but I only have two. Maybe I'll try the N.O.S. GE 12BH7A in the middle and the two JAN 5814 on the sides as well.
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    Dave_in_Va
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    • Post n°11

    VTA ST - 120 Finished and up and running!!! Empty Re: VTA ST - 120 Finished and up and running!!!

    Post by Dave_in_Va Sat Sep 21, 2013 9:17 pm

    I have lots of 12AU7's and 5963's but found most of them to be microphonic in my pre amp (SP/PH 10). Would the middle position in the VTA ST 70 be a more forgiving spot to try some of these tubes. They sure look NOS.
    Thanks.
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    Analog Man
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    • Post n°12

    VTA ST - 120 Finished and up and running!!! Empty Re: VTA ST - 120 Finished and up and running!!!

    Post by Analog Man Sat Sep 21, 2013 9:20 pm

    Dave_in_Va wrote:I have lots of 12AU7's and 5963's but found most of them to be microphonic in my pre amp (SP/PH 10). Would the middle position in the VTA ST 70 be a more forgiving spot to try some of these tubes. They sure look NOS.
    Thanks.
    Yes! According to Bob Latino, the center position on the driver board is the most influential on the sound. As I have experimented, I found that this is true!
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    Bob Latino
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    • Post n°13

    VTA ST - 120 Finished and up and running!!! Empty Re: VTA ST - 120 Finished and up and running!!!

    Post by Bob Latino Sat Sep 21, 2013 9:25 pm

    Dave_in_Va wrote:I have lots of 12AU7's and 5963's but found most of them to be microphonic in my pre amp (SP/PH 10). Would the middle position in the VTA ST 70 be a more forgiving spot to try some of these tubes. They sure look NOS.
    Thanks.
    Dave,

     That center position driver tube is LESS forgiving of hum, noise, microphonics or any other tube abnormality. If that center tube has any issues, the issues wil be passed on throughout the amp ..

    Bob
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    Analog Man
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    • Post n°14

    VTA ST - 120 Finished and up and running!!! Empty Re: VTA ST - 120 Finished and up and running!!!

    Post by Analog Man Sat Sep 21, 2013 9:28 pm

    Bob Latino wrote:
    Dave_in_Va wrote:I have lots of 12AU7's and 5963's but found most of them to be microphonic in my pre amp (SP/PH 10). Would the middle position in the VTA ST 70 be a more forgiving spot to try some of these tubes. They sure look NOS.
    Thanks.
    Dave,

     That center position driver tube is LESS forgiving of hum, noise, microphonics or any other tube abnormality. If that center tube has any issues, the issues wil be passed on throughout the amp ..

    Bob
    Thanks for that! You sure are a wealth of knowledge. I really appreciate you!
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    Analog Man
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    • Post n°15

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    Post by Analog Man Sat Sep 21, 2013 9:30 pm

    Would tube shields help on the center driver tube?
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    sKiZo
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    • Post n°16

    VTA ST - 120 Finished and up and running!!! Empty Re: VTA ST - 120 Finished and up and running!!!

    Post by sKiZo Sat Sep 21, 2013 11:43 pm

    Tube shields ...

    - Can reduce microphonics in a microphonic tube
    - Can increase noise in an otherwise clean tube
    - Can reduce noise in a high gain amp
    - Can change the tone by increasing grid capacitance
    - Can cause noise due to sympathetic vibration
    - All of the above
    - None of the above
    - Some of the above

    There ... hope that helps ... clown 
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    • Post n°17

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