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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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MarcVBelgium
EddieRock
arledgsc
Rich
8 posters

    My first kit ever. My VTA ST-120

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    Jerryfan


    Posts : 7
    Join date : 2014-10-03

    My first kit ever. My VTA ST-120 - Page 2 Empty Re: My first kit ever. My VTA ST-120

    Post by Jerryfan Wed Nov 05, 2014 11:09 pm

    Rich, how do the ARC and the ST120 compare?
    Rich
    Rich


    Posts : 32
    Join date : 2013-01-17

    My first kit ever. My VTA ST-120 - Page 2 Empty Re: My first kit ever. My VTA ST-120

    Post by Rich Thu Nov 06, 2014 12:05 am

    Jerryfan wrote:Rich, how do the ARC and the ST120 compare?

    Hello Jerryfan,
    Both amps are almost the same power and both amps were using kt-120.
    St120 is not as commercial as ARC and ARC is a very well known brand, but I have to admit that overall, I prefer my St120, it is a better match for my dynaudios. ARC is a little bit thin in its sound and seems to lack some authority in bass.
    I prefer the e80cc drivers performance instead the ARC's "supertube" 6H30 driver.
    Btw, vs60 weights about half of St120. Light weight transformers? Maybe.

    Best regards.
    avatar
    Jerryfan


    Posts : 7
    Join date : 2014-10-03

    My first kit ever. My VTA ST-120 - Page 2 Empty Re: My first kit ever. My VTA ST-120

    Post by Jerryfan Thu Nov 06, 2014 12:41 am

    Good to know. Ill be getting my st120 next week. Can't wait!
    Rich
    Rich


    Posts : 32
    Join date : 2013-01-17

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    Post by Rich Sat Nov 08, 2014 11:07 am

    Jerryfan wrote:Good to know. Ill be getting my st120 next week. Can't wait!

    You won't be dissapointed at all.
    It is one of the best amps in market, and yes, even better than many "mega bucks" famous brands amps around.

    Best regards, good luck and enjoy it.
    avatar
    StephenMH


    Posts : 7
    Join date : 2014-08-30
    Age : 68
    Location : Aurora, Co.

    My first kit ever. My VTA ST-120 - Page 2 Empty Dynaco ST70 The Best Minimum Budget Simple Upgrade!

    Post by StephenMH Mon May 18, 2015 7:06 pm

    Rich and or any one else, what made you choose the ST-120 over the others? And I would love to Rebuild a Tube Amp maybe later A Tube preamp. I know Building computers is Different than Building Amps and Preamps. By not having experience in using or reading Schematics is it possible for me to Build a Tube Amp? I have a soldering Machine, took a small workshop at an audio show on soldering. and I seen a few YouTube on Soldering. Is there Hope? Question  Exclamation  bounce    cheers  bounce


    Hi Stephen,

    The VTA ST-120 is just a higher powered version of the VTA ST-70. Both amps use the same driver circuit but the resistors set is slightly different from amp to amp. The VTA ST-120 does not "sound any better" than the VTA ST-70 but it does have about 3 dB of extra headroom over the ST-70. It is nice to have a little extra headroom on musical peaks. Which amp would better suit your needs is determined by ..

    1. The efficiency of your speakers
    2. The size of your room
    3. The type of music and the general loudness level at which you play your music

    Lower efficiency speakers in a large room playing rock music at higher volume levels will need an amp with more power.

    The assembly manuals for all the VTA amp kits are written in a step by step fashion. You don't really need to know how to read a schematic to assemble one of the amps. As long as you can follow directions, use simple hand tools (screwdriver, pliers, wire stripper/cutter) and solder with a soldering pencil, you can build the amp. Rarely does anyone have a major problem in getting one of the amps together and working properly. If you do run into an issue, I am here by Email and/or phone for customer support.

    New Below: 2015-05-18 : 05:01:12 P.M

    Hello Bob,
       Forgive me for getting back late. We found out My Girlfriend got cancer two or three months after I last wrote here. I have Procrastination Skill that I'm taking time to undo. Lol...

       Like I mention Before It would be nice to connect with you before we move from Cambridge, Ma. to Aurora, Co.

       I had enough time to think what direction to go with my Two Dynaco ST70(Bought both from E-Bay). One was Rebuild from ground up; last year I had it hooked up for about a year(replace my Jolida JD801A one of my Favorite tube Amps needed Speaker terminal). Then it went out(Panic for a few second) Lol..; found out it was the fuse(did not put back in the setup instead use BK ST1400). It might need the Bios calibrated, maybe the tubes upgraded(everything was working before the fuse went out).

       The second Dynaco is in Original Condition when I last hook it up, was working. One of the Reason I Bought it because the chrome was in Great shape and of course it works. Will like to find out the Best way to Rebuild or Upgrade for the Best Sound and Best Value. I have Champagne taste and Beer pocketbook. I would like to do it my self. If I don't I've got someone in mind That repairs and upgrade etc...; he already have a Driver board for the 6Au6 tube set by Triode for about $75.
    http://www.triodeelectronics.com/st70boardparts.html If I upgrade it, would like to keep it simple with less parts if possible. It will not be my main amp; I have a collection of other Amp and Preamp. Yes this is one of the many hobbies I have(maybe to many). Lol Thank You for you Help!  

       When I save enough, thinking about getting the Dynaco ST120 later.
    (A.)The Speakers are the Von Schweikert VR-4jr; Recomed Power 20-300, Sens. 89, 6 ohms avg. http://www.enjoythemusic.com/magazine/equipment/1204/vonschweikertvr4jr.htm
    (B.)Room size about 9ft-W, 10ft-L, 8ft-H
    (C.)My Main Love is Funk Jazz, Fusion Jazz and Funk! Other music is Classical and getting more into Traditional Jazz like Miles Davis(his fault), John Coltrane and Thelonious Monk(Loving the Monk) Etc...the list is growing on me(maybe age- hit the big sixty May 2)

       The Second Speaker is the Definitive Technology BP2002TL that's more for my Hometheater(sometimes music and Video music concerts). Mike Allen President of Jolida Tube said to use all tubes for Hometheater Surround. I was fortunate to buy that JD801A(he said for me to get). It was a Good ideal I thought tubes are less fatigue on the Ears. The downside take up a lot of room. Maybe in the future just for the Front-L-R for the Hometheater. Like I had it before the Move from Cambridge, Ma. Now I have a separate room one for Hometheater and one room for the Music. Later for the Man Cave in the Basement future plans Etc..  

      Almost forgot, A first time for me, What is the easiest and Simplest way to Calibrate the Bios on the Dynaco ST70?

       Again Thank You for Your Time and Patients! Enjoy the Best of a Healthy Soulful Prosperous Life! & Allow the Music To Heal!  farao

    Peace, Love and Soulful Oneness! Stephen
    avatar
    StephenMH


    Posts : 7
    Join date : 2014-08-30
    Age : 68
    Location : Aurora, Co.

    My first kit ever. My VTA ST-120 - Page 2 Empty Congratulation on your Dynaco ST120!

    Post by StephenMH Mon May 18, 2015 7:27 pm

    Hello Rich,

       Read the Above from me to Bob. Forgive me for getting Back Late(like real Late).

       When I finish getting My two Dynaco ST70 up to part; I'm Thinking of getting the Dynaco ST120 or close to it. When I get my budget right.

        Congratulation on getting your ST120 Back! cheers   How is it working out for You?

    Enjoy the Best of a Healthy Soulful Prosperous Life! & Allow the Music To Heal!  
    Peace, Love and Soulful Oneness! Stephen


    Last edited by StephenMH on Mon May 18, 2015 7:36 pm; edited 1 time in total
    Bob Latino
    Bob Latino
    Admin


    Posts : 3260
    Join date : 2008-11-26
    Location : Massachusetts

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    Post by Bob Latino Mon May 18, 2015 7:31 pm

    "Almost forgot, A first time for me, What is the easiest and Simplest way to Calibrate the Bios on the Dynaco ST70?"

    If it is a stock Dynaco ST-70 with the stock driver board and bias pots > Get your multimeter and set if for 0 to 2 volts DC. Place the red probe in the hole on one of the front tube sockets that say "Biaset 1.56 V". Place the black probe anywhere on the chassis and turn the bias pot for that channel until your meter reads 1.56 volts. Then do the same thing on the other channel. NOTE - Dynaco ran their tubes hard with a fairly high bias current. (50 milliamps per each output tube) Conventional wisdom now is to set the bias a little lower at about 1.25 volts per channel. This will give about 40 milliamps of bias current per each output tube. The amp will sound the same and the output tubes will last longer.

    Bob
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    StephenMH


    Posts : 7
    Join date : 2014-08-30
    Age : 68
    Location : Aurora, Co.

    My first kit ever. My VTA ST-120 - Page 2 Empty Re: My first kit ever. My VTA ST-120

    Post by StephenMH Mon May 18, 2015 7:58 pm

    Bob Latino wrote:"Almost forgot, A first time for me, What is the easiest and Simplest way to Calibrate the Bios on the Dynaco ST70?"

    If it is a stock Dynaco ST-70 with the stock driver board and bias pots > Get your multimeter and set if for 0 to 2 volts DC. Place the red probe in the hole on one of the front tube sockets that say "Biaset 1.56 V". Place the black probe anywhere on the chassis and turn the bias pot for that channel until your meter reads 1.56 volts. Then do the same thing on the other channel. NOTE - Dynaco ran their tubes hard with a fairly high bias current. (50 milliamps per each output tube) Conventional wisdom now is to set the bias a little lower at about 1.25 volts per channel. This will give about 40 milliamps of bias current per each output tube. The amp will sound the same and the output tubes will last longer.

    Bob

    WoW! Bob You're Fast!

       So you say changing and Calibrating the Bios have nothing to do with the Sound Quality?
    I do not have them hooked up at this moment; will do within the next two days.

       On my other Rebuild ST70 will that be different? They're not all the same because of the Driver Board?

       On my Multimeter it has V-AC DC and mA-AC DC Which One? Question  

    Thank You for Your Help! Stephen
    Bob Latino
    Bob Latino
    Admin


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    Post by Bob Latino Mon May 18, 2015 8:06 pm

    If the driver board is a stock driver board or a replacement stock type driver board, then what I mentioned above will still hold true. If you have a different driver board then, then the bias instructions may be different. If you can post photos of the tops of your ST-70's, we can figure it out for you ..

    You set the meter to V (volts) and make sure that you are on the DC scale (not the AC scale).

    Bob
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    StephenMH


    Posts : 7
    Join date : 2014-08-30
    Age : 68
    Location : Aurora, Co.

    My first kit ever. My VTA ST-120 - Page 2 Empty Re: My first kit ever. My VTA ST-120

    Post by StephenMH Mon May 18, 2015 8:42 pm

    It says DC in the top Left hand side. and the numbers are moving in the middle. Even tho its
    not hooked up to anything is that normal?

    When I do The Bios Calibration, I will take some pictures of it. Which I want to do any how. Believe it or not, another one of my Hobbies is Photography!

    Keep this up will be an Audio Electrician(just sort of kidding, I'm a wanna be)!  lol!
    You're Great Thanks again!
    Stephen
    deepee99
    deepee99


    Posts : 2244
    Join date : 2012-05-23
    Location : Wallace, Idaho

    My first kit ever. My VTA ST-120 - Page 2 Empty Re: My first kit ever. My VTA ST-120

    Post by deepee99 Mon May 18, 2015 10:03 pm

    Hello Rich in Mexico. Beautiful build. You made a great choice.

    Rich likes this post

    Rich
    Rich


    Posts : 32
    Join date : 2013-01-17

    My first kit ever. My VTA ST-120 - Page 2 Empty Re: My first kit ever. My VTA ST-120

    Post by Rich Sun Aug 16, 2020 1:26 am

    Well, long time ago since I built this amp, and after I sold it to a good friend, this week I`ve got it back!
    Some mods have been done like KT90 tubes instead of original KT120, WBT Input and output outlets fitted at the back as well as an IEC power connector.
    After more than 7 years, still working flawless.

    https://photos.app.goo.gl/P7N7u46Gbwt81z7BA
    https://photos.app.goo.gl/98us4o9Jx1b9HfJf8
    https://photos.app.goo.gl/AYCymSacJfyVesS86

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