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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


4 posters

    Voltage Amplifier Tube on VTA

    mantha3
    mantha3


    Posts : 303
    Join date : 2010-11-10

    Voltage Amplifier Tube on VTA Empty Voltage Amplifier Tube on VTA

    Post by mantha3 Sat Apr 16, 2011 10:38 pm

    I'm learning as I go and digging it. I've been trying to understand fully the ST120 amp I now own. I've been looking at the schematic and tracing all the parts... what does what. cool stuff

    I have the book Beginners Guide to Tube Audio Design... I also have been looking at Booxhound Amp also to learn. This amp is real stripped down. Looking at this and understanding this amp helps as it is real basic. I then can look at the ST120 schematic and I get what most of everything does.

    I am not really getting what is going on in the 12AT7 in the center spot. I don't get why only 1 is needed. I would think the amp needs 2 of these. each tube would handle a channel and have the signal run to the grid (assuming 2 tubes)... Then the Cathode and Plate do what they do. I don't get how the center 12at7 handles both R and L channels. Do both channels go to the grid? then the amplified signal is then split to R and L ?

    Just trying to learn. This site rocks!


    Thanks all!
    Andy
    Luddite
    Luddite


    Posts : 233
    Join date : 2009-02-04
    Age : 74
    Location : Texas

    Voltage Amplifier Tube on VTA Empty Re: Voltage Amplifier Tube on VTA

    Post by Luddite Sat Apr 16, 2011 11:31 pm

    mantha3 wrote:
    I am not really getting what is going on in the 12AT7 in the center spot. I don't get why only 1 is needed. I would think the amp needs 2 of these. each tube would handle a channel and have the signal run to the grid (assuming 2 tubes)... Then the Cathode and Plate do what they do. I don't get how the center 12at7 handles both R and L channels. Do both channels go to the grid? then the amplified signal is then split to R and L ?

    Just trying to learn. This site rocks!


    Thanks all!
    Andy

    Andy,

    The short answer is that the 12AT7 is a dual triode. In other words it is basically two triode tubes contained within a single glass envelope. I'll leave further elaboration to those more astute tube experts here on the forum.

    Best Regards,
    Charlie
    mantha3
    mantha3


    Posts : 303
    Join date : 2010-11-10

    Voltage Amplifier Tube on VTA Empty Re: Voltage Amplifier Tube on VTA

    Post by mantha3 Sun Apr 17, 2011 8:58 am

    Ahhh

    I was digging around the net a bit more after I read this from you Ludite. I think I'm getting it a little more from seeing this -

    Voltage Amplifier Tube on VTA 12AT7

    So I'm guessing the right channel is running on one side (say it drives one grid via pin 7)and then the left is running the other (pin 2)...

    This helped a lot. I think I'm getting the phase splitters now a little better as well. So you have two signals out of phase... I'm guessing the 12AT7 is having a signal phase handled on each side of the tube... So one phase signal drives the Grid on pin 7 and then the signal out of phase goes to pin 2's grid.

    Lots going on in these little 12AT7 tubes! Having fun learning.


    Thanks
    ATM
    avatar
    Disles1


    Posts : 17
    Join date : 2010-12-21
    Location : Calgary, Alberta

    Voltage Amplifier Tube on VTA Empty Re: Voltage Amplifier Tube on VTA

    Post by Disles1 Thu Apr 21, 2011 6:49 pm

    mantha3 wrote:I'm learning as I go and digging it. I've been trying to understand fully the ST120 amp I now own. I've been looking at the schematic and tracing all the parts... what does what. cool stuff

    I have the book Beginners Guide to Tube Audio Design... I also have been looking at Booxhound Amp also to learn. This amp is real stripped down. Looking at this and understanding this amp helps as it is real basic. I then can look at the ST120 schematic and I get what most of everything does.

    Thanks all!
    Andy

    Andy, thank you for posting the link to Booxhound. I too am learning about tubes, amps, etc. and so your experiences help me. Ken in Calgary.
    mantha3
    mantha3


    Posts : 303
    Join date : 2010-11-10

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    Post by mantha3 Thu Apr 21, 2011 8:15 pm

    Nice

    Beginners Guide to Tube Audio Design is a decent book. It is written more for push / pull tube amps which is good for us ST70/ST120 etc owners. I think Tubes4hifi have an amazon store selling it so you can support these guys
    Roy Mottram
    Roy Mottram
    Admin


    Posts : 1839
    Join date : 2008-11-30

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    Post by Roy Mottram Thu Apr 21, 2011 9:19 pm

    yes, ANY book or music or anything Amazon sells, if you buy it thru our website we make about 2% on it, not much, but hey . . . .
    so if you want something semi-expensive I can add it to the store anytime, or anytime you're buying some music . . . .
    http://astore.amazon.com/tub02-20

    Sponsored content


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