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    Voltage Amplifier Tube on VTA

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    mantha3

    Posts : 298
    Join date : 2010-11-10

    Voltage Amplifier Tube on VTA

    Post by mantha3 on 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

    Posts : 235
    Join date : 2009-02-04
    Age : 66
    Location : Texas

    Re: Voltage Amplifier Tube on VTA

    Post by Luddite on 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

    Posts : 298
    Join date : 2010-11-10

    Re: Voltage Amplifier Tube on VTA

    Post by mantha3 on 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 -



    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

    Disles1

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

    Re: Voltage Amplifier Tube on VTA

    Post by Disles1 on 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

    Posts : 298
    Join date : 2010-11-10

    Re: Voltage Amplifier Tube on VTA

    Post by mantha3 on 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

    tubes4hifi
    Admin

    Posts : 1261
    Join date : 2008-11-30

    Re: Voltage Amplifier Tube on VTA

    Post by tubes4hifi on 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

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