The Dynaco Tube Audio Forum

Dedicated to the restoration and preservation of all original Dynaco tube audio equipment - Customer support for Dynaco VTA tube amp kits, all Tubes4hifi.com products and all Dynakitparts.com products


    My ST-70 Rebuild

    Share

    lwrs10

    Posts : 12
    Join date : 2012-02-29

    My ST-70 Rebuild

    Post by lwrs10 on Thu Mar 01, 2012 7:39 pm

    Bought a couple of ST-70's for $100 bucks recently. Decided they do not sound very good untouched.....




    The restoration has started. Here is what I had to work with....












    As you can see, it is a little bit of a hackjob. Spray paint, terrible wiring job, ETC. Last night the rectifier tube exploded.

    More to come...
    __________________

    lwrs10

    Posts : 12
    Join date : 2012-02-29

    Re: My ST-70 Rebuild

    Post by lwrs10 on Thu Mar 01, 2012 7:41 pm

    Took it apart today so I can get the chassis powder coated gloss black.










    What a project.....took me all morning to get it down like this.

    lwrs10

    Posts : 12
    Join date : 2012-02-29

    Re: My ST-70 Rebuild

    Post by lwrs10 on Thu Mar 01, 2012 7:41 pm

    Growing a freshly painted transformer garden....


    Bob Latino
    Admin

    Posts : 2411
    Join date : 2008-11-26
    Location : Massachusetts

    Re: My ST-70 Rebuild

    Post by Bob Latino on Thu Mar 01, 2012 8:48 pm

    Hi Randy,

    I like the blue color that you chose for your transformers. I love to see start to finish restorations of Dynaco tube gear. Keep this thread alive and show us more photos of the rebuilt amp as it comes together.

    Bob

    lwrs10

    Posts : 12
    Join date : 2012-02-29

    Re: My ST-70 Rebuild

    Post by lwrs10 on Thu Mar 01, 2012 8:56 pm

    Bob Latino wrote:Hi Randy,

    I like the blue color that you chose for your transformers. I love to see start to finish restorations of Dynaco tube gear. Keep this thread alive and show us photos as the rebuilt amp comes together.

    Bob

    I painted them gloss black Bob. The tape is blue. I would have liked to paint them blue, but it would border tacky. For my first tube amp restoration that many people would see I chose a more contemporary color.

    Bob Latino
    Admin

    Posts : 2411
    Join date : 2008-11-26
    Location : Massachusetts

    Re: My ST-70 Rebuild

    Post by Bob Latino on Thu Mar 01, 2012 9:01 pm

    Ok - lol ... My monitor on the computer here must be off a little ... Not just the tape but the transformers look a little blue (at least) on this monitor .. Maybe it's a bluish reflection from the blue sky above ?

    Bob

    anbitet66

    Posts : 132
    Join date : 2009-12-23
    Location : Valley Stream, NY

    Re: My ST-70 Rebuild

    Post by anbitet66 on Thu Mar 01, 2012 9:27 pm

    Hey Randy,

    I have the same SDS 6AU6 board in an ST70 I constructed a little over a year ago. If you keep that board, I'd like an opinion since you can compare the original amp and the one you are rebuilding. I like mine, but some resistor values need to be juggled in order to get the most from the board. Stock values could be a starting point, but cathode and plate resistors need tweaking in my opinion. I'm still working on mine, when I can find the time that is.

    Good luck with your $100 purchase Shocked (no smiley for jealous)

    Tony

    lwrs10

    Posts : 12
    Join date : 2012-02-29

    Re: My ST-70 Rebuild

    Post by lwrs10 on Fri Mar 02, 2012 11:24 pm

    Made some progress today.......

    Got the chassis back form the powder coating place. Got the VTA board in the mail. Built it. Got a solder headache right now.....will assemble the amp tomorrow!














    harpy

    Posts : 94
    Join date : 2012-02-04

    Re: My ST-70 Rebuild

    Post by harpy on Sat Mar 03, 2012 1:20 am

    I like the sleeves on your cap leads and cut just right. Nice attention to detail.

    lwrs10

    Posts : 12
    Join date : 2012-02-29

    Re: My ST-70 Rebuild

    Post by lwrs10 on Sat Mar 03, 2012 1:46 am

    harpy wrote: I like the sleeves on your cap leads and cut just right. Nice attention to detail.


    Can't take credit for that one. Just following Bobs wonderful instructions.

    lwrs10

    Posts : 12
    Join date : 2012-02-29

    Re: My ST-70 Rebuild

    Post by lwrs10 on Sat Mar 03, 2012 9:55 pm

    And a teaser pic. Will do a full update once i finish everything...



    lwrs10

    Posts : 12
    Join date : 2012-02-29

    Re: My ST-70 Rebuild

    Post by lwrs10 on Mon Mar 05, 2012 11:34 am

    And its finished. I put the front panel on upside down so had to fix that. I did the best I could with the wiring working with the old cloth wire from the transformers and my lack of experience with this(my first amp I have built). Anyways......let me know what you think!












    Last edited by lwrs10 on Mon Mar 05, 2012 3:10 pm; edited 1 time in total

    stewdan

    Posts : 161
    Join date : 2010-03-07
    Age : 78
    Location : Houston Texas

    Re: My ST-70 Rebuild

    Post by stewdan on Mon Mar 05, 2012 3:05 pm

    Hi --

    To me your craftmanship is superb!!

    I guess the important question is "how does it sound??"

    How much did the powder coating of one chassis and bottom plate cost?

    Good Listening,
    Stew

    lwrs10

    Posts : 12
    Join date : 2012-02-29

    Re: My ST-70 Rebuild

    Post by lwrs10 on Mon Mar 05, 2012 3:12 pm

    stewdan wrote:Hi --

    To me your craftmanship is superb!!

    I guess the important question is "how does it sound??"

    How much did the powder coating of one chassis and bottom plate cost?

    Good Listening,
    Stew

    it sounds great! alot better than I expected it to. The powder coat only cost $30. But the chassis was so pitted it did not turn out as good as i wanted it too....

    stewdan

    Posts : 161
    Join date : 2010-03-07
    Age : 78
    Location : Houston Texas

    Re: My ST-70 Rebuild

    Post by stewdan on Mon Mar 05, 2012 3:33 pm

    Hi Again --

    Nice to hear that they sound good to you. They should improve with continued breakin. You can also do some tube rolling. The center tube seems to make a lot of difference on the VTA70. There have been some posts about which 9-pin tubes sound the best.

    I have some Dynaco Mark III Mono Amps and I have tried different Driver Cards on them. To me and others that I played them for, the best sounding driver was Roy's VTA/MK3 Low Gain Board, which is basically 1/2 of your ST-70 board.

    Recently, I acquired a set of his VTA/MK3/Octal Driver boards that use 6SN7 tubes and am anxiosly awaiting some parts before I can complete the pair.

    Enjoy listening to your "new" ST-70!!

    Stew

    tubes4hifi
    Admin

    Posts : 1286
    Join date : 2008-11-30

    Re: My ST-70 Rebuild

    Post by tubes4hifi on Thu Mar 08, 2012 3:58 am

    your 2nd photo down (post 12), that's the kind of photo I like, that's the way I listen to my music,
    dark, with just the tube glow and the music . . . .
    permission to add another great customer photo on my website?
    I might need to add my own gallery of favority customer photos!

    lwrs10

    Posts : 12
    Join date : 2012-02-29

    Re: My ST-70 Rebuild

    Post by lwrs10 on Thu Mar 08, 2012 9:32 pm

    tubes4hifi wrote:your 2nd photo down (post 12), that's the kind of photo I like, that's the way I listen to my music,
    dark, with just the tube glow and the music . . . .
    permission to add another great customer photo on my website?
    I might need to add my own gallery of favority customer photos!

    Sure thing! I would be honored!

    tubes4hifi
    Admin

    Posts : 1286
    Join date : 2008-11-30

    Re: My ST-70 Rebuild

    Post by tubes4hifi on Fri Mar 09, 2012 12:25 am

    thanks much!!

    Sponsored content

    Re: My ST-70 Rebuild

    Post by Sponsored content Today at 6:22 pm


      Current date/time is Sun Dec 04, 2016 6:22 pm