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    Another Tube newbie ST120 build

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    pigface

    Posts : 70
    Join date : 2011-04-10
    Location : pittsburgh

    Another Tube newbie ST120 build

    Post by pigface on Sat Apr 23, 2011 1:18 pm

    After much thinking on wether to buy a used tube amp or build a kit amp I deceied to
    build a ST120 . The thinking was because I know little about electronics or sterio design .
    And I never have built anything like this before !
    I now know a little more than before but that is still little Shocked . I did a bunch of reading on this
    fourum and others and alot of reviews to help with the build .

    The kit is well thought out and comes with very good instructions and diagrams that
    made it easy . So almost anyone could build this kit .

    I decided to get the power supply upgrade caps with the kit. After reading a few good
    reviews on coupling caps I decided to go with the Mundorf silver and oil caps of the factory specs , as
    the coupling cap upgrade . And like another build on here , upgrade the resistors with
    Tantalum resistors . I also did the diode mod for the rectifier socket and added a Ericson
    GFCI plug to help with rectifier life , Since we have been having more short and long
    power outages here the last couple years . And the reset on plug works perfect .

    The build went pretty easy with only a couple mistakes that I cought after double , triple
    and quadruple checking everything during the build . The circut board which I thought
    would give me the most headaches turned out to be the easiest part !
    I decided to go with the KT120 power tubes . And Mullard CV4024 outer tubes a
    Telefunken 12AT7 center tube and a Mullard GZ33 rectifier . I also bought a couple
    copper cap rectifiers just in case .

    After finishing all the soldering , and pluging it in , the preamp tubes lit right up and after
    plugging all the power tubes in they lit up perfect too and biased up the first time ! Much
    to my suprise . It is perfectly quiet and sounds awesome . This is my first tube amp and
    I’m hooked . And it does seem to sound better because I built it myself . Twisted Evil


    Here it is with some of the wireing complete . I used the 4 ohm taps for my old infinity kappa speakers I'm useing .


    Pretty much complete.




    Inital start up was with the weber copper cap rectifier just in case , I didn't want to blow up a expensive mullard !
    if something wasn't right . The switch back to the Mullard did seem to knock down the power a bit .




    Temporary setup.


    It shure looks nice in the dark !

    j beede

    Posts : 316
    Join date : 2011-02-07
    Location : California

    Re: Another Tube newbie ST120 build

    Post by j beede on Sat Apr 23, 2011 1:42 pm

    Very nice. Sounds like you had plenty of fun building your amplifier--very good. I like how you routed and tied off the wires. I never get tired of seeing triode and pentode tubes glow. Yes, you did well to use new components in building a "fresh" amp. If you happen to have lots of old, unused oil filled caps you can always ship them to me for proper disposal Wink

    Luddite

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

    Re: Another Tube newbie ST120 build

    Post by Luddite on Sat Apr 23, 2011 3:24 pm

    Superb workmanship...everything looks great...enjoy!

    Uh, by the way, you don't happen to live in Oklahoma do you? If I didn't know better, I would swear that your first picture was taken in my old workshop. Same panelling, same pegboard, and same bench surface...some kinda' coincidence!

    Best Regards,
    Charlie

    ArlanB

    Posts : 52
    Join date : 2011-01-23
    Age : 69
    Location : Santa Cruz, California

    Another Tube Newbie ST120 Build

    Post by ArlanB on Sat Apr 23, 2011 5:53 pm

    Your images do not reflect a first time builders effort. You work is excellent. I know that you will enjoy the ST120 more and more as the hours go by. I purchased one of the first 3 ST120 kits that Bob Latino produced almost 3 years ago. I ordered my kit in stock form without upgrades and have not had a single regret. The amp worked on the first smoke test and have not looked back. The only trouble that I have had is with the power tubes. First three sets were of Eastern European manufacture and all three sets had failures within nine months or less. The reissue of a famous British brand lasted only 11 days. Currently I am using KT88SC tubes issued by an oriental manufacture under the Penta Labs name. They are now almost a year old with over 400 hours and are continuing to prove to me that not all things oriental are bad.

    Kit building can be fun. I know, this is my eight kit build. I started in high school in the early 60's with another well known kit manufacturer and ended with this kit. Now I am looking to build a new preamp. It never ends when you have the bug.

    Regards,

    ArlanB

    pigface

    Posts : 70
    Join date : 2011-04-10
    Location : pittsburgh

    Re: Another Tube newbie ST120 build

    Post by pigface on Sat Apr 23, 2011 6:28 pm

    Charlie , Im in pittsburgh, so , no not your workshop . Did yours have all kind of fishing tackle crap on the wall too? Smile

    Arlan , I'm lucky as I'm good with my hands and can usually build something when I put my mind to it . I think it took me a little less than 15-20 hours to build this , And had fun doing it too. Looking back at the pictures I could have spent a little more time making the circut board look a little neater ( I'm a little impatient sometimes Embarassed ) but it would still play the same .
    I always looked in on the kids in highschool shop classes that were building radios and such but never had any interest in it then .
    I've also been thinking of doing a preamp also ( since my old Carver seems to be getting a weak right channel). But it seems , I don't know , tougher and more things to go wrong and since I have little hope of troubleshooting it myself , and seeing the post on the SP12 scared me . But I might try it anyway . That or the phono preamp.
    Thanks for the comments.

    Luddite

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

    Re: Another Tube newbie ST120 build

    Post by Luddite on Sun Apr 24, 2011 2:10 am

    pigface wrote:Charlie , Im in pittsburgh, so , no not your workshop . Did yours have all kind of fishing tackle crap on the wall too? Smile

    Well, not out in the shop, just lots of general and woodworking tools at one end and my "tech" bench at the other. While I lived there (12 years), I built a Dynaco ST70 amp, PAS3 preamp, a tube headphone amp, and a pair of folded horn speakers. Since I moved back to Texas, I've built an SET amp, an (octal) tube preamp, a Dynaco ST35, and a pair of "clone" Dynaco A25's, plus I rebuilt a Dynaco FM3 tuner. I'm planning at least one more project (another "PAS" preamp) before the old hands get too stiff to have the necessary dexterity.

    Best Regards,
    Charlie

    mantha3

    Posts : 298
    Join date : 2010-11-10

    Re: Another Tube newbie ST120 build

    Post by mantha3 on Mon Apr 25, 2011 10:11 pm

    Nice Amp! I may have to do some silver in oil caps one day.

    Run the Copper Cap if you decide to turn the amp up pretty loud. Sounds better and the nice Mullard will be in a safe place!

    The sound will just get better and better for the next 100 some hours. Enjoy!

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