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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


    M-125 Build

    Dave_in_Va
    Dave_in_Va

    Posts : 382
    Join date : 2013-04-02

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    Post by Dave_in_Va on Thu Nov 07, 2019 11:26 am

    KenGaler
    KenGaler

    Posts : 76
    Join date : 2019-10-11

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    Post by KenGaler on Thu Nov 07, 2019 12:57 pm

    Thank you
    KenGaler
    KenGaler

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    Post by KenGaler on Fri Nov 08, 2019 3:11 pm

    Button head screws softened it up.

    M-125 Build - Page 2 Model-Front-4
    KenGaler
    KenGaler

    Posts : 76
    Join date : 2019-10-11

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    Post by KenGaler on Sat Nov 09, 2019 5:29 pm

    AC Controller

    M-125 Build - Page 2 AC-Unit-Front

    M-125 Build - Page 2 AC-Unit-Rear
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    audiobill

    Posts : 421
    Join date : 2014-03-13
    Location : Albany, NY

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    Post by audiobill on Sun Nov 10, 2019 10:52 am

    Very cool!
    KenGaler
    KenGaler

    Posts : 76
    Join date : 2019-10-11

    M-125 Build - Page 2 Empty Metal

    Post by KenGaler on Mon Nov 25, 2019 12:41 pm

    Between the two amps and the AC unit there are a total of 18 parts that need to be machined. Most need machining on 2-4 sides. The first quote I received using 304 SS was just under $6K. AL was only about $500 less. GASP!

    I got lucky and a friend of a friend has a CNC in his garage. He quoted $2100 for AL. So, I'm going with that.

    Ken
    KenGaler
    KenGaler

    Posts : 76
    Join date : 2019-10-11

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    Post by KenGaler on Thu Dec 12, 2019 10:14 am

    PCBs came in

    M-125 Build - Page 2 B-Filter-PCB

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    avi.inc

    Posts : 61
    Join date : 2009-08-03
    Age : 67
    Location : L.A.

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    Post by avi.inc on Fri Dec 13, 2019 7:26 pm

    KenGaler
    KenGaler

    Posts : 76
    Join date : 2019-10-11

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    Post by KenGaler on Tue Dec 17, 2019 10:58 am

    avi.inc wrote:This is what the pro use.

    https://en.wikipedia.org/wiki/Speakon_connector

    I do like them and may wind up changing to them. Thanks
    Dahlberg
    Dahlberg

    Posts : 132
    Join date : 2016-09-27
    Age : 59
    Location : Sweden

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    Post by Dahlberg on Tue Dec 17, 2019 6:54 pm

    I used the Neutrik STX series  for a project, they are really nice  Cool

    M-125 Build - Page 2 663-nlt4fp

    M-125 Build - Page 2 659-nlt4mx
    KenGaler
    KenGaler

    Posts : 76
    Join date : 2019-10-11

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    Post by KenGaler on Wed Dec 18, 2019 12:03 pm

    Some electronics porn, PCBs stuffed.  Waiting for cleaner to come in so a bit dirty.  I added 3D printed mounts on the pre-amp PCB to keep the caps from moving too much.

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    M-125 Build - Page 2 Pre-Amp-stuffed
    Dahlberg
    Dahlberg

    Posts : 132
    Join date : 2016-09-27
    Age : 59
    Location : Sweden

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    Post by Dahlberg on Wed Dec 18, 2019 6:59 pm

    Looks nice Smile I'm guessing you are skipping the "supplementary cap module", but what's R2 for ?
    KenGaler
    KenGaler

    Posts : 76
    Join date : 2019-10-11

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    Post by KenGaler on Thu Dec 19, 2019 11:21 am

    Dahlberg wrote:Looks nice Smile I'm guessing you are skipping the "supplementary cap module", but what's R2 for ?

    Yeah, I replaced the cap module and the chassis cap. R2 is just a 500K bleeder, about 1/2w.
    KenGaler
    KenGaler

    Posts : 76
    Join date : 2019-10-11

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    Post by KenGaler on Thu Dec 19, 2019 1:33 pm

    I'm in a bit of a pickle. I have the transformers ready for painting but nowhere warm enough to paint them. Can't inside because it's toxic, the garage is too cold even in NC. ERG! Maybe I can use a couple space heaters in the garage.
    Dahlberg
    Dahlberg

    Posts : 132
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    Age : 59
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    Post by Dahlberg on Thu Dec 19, 2019 7:36 pm

    A couple of halogen flood lights gets pretty hot. Don't know if anyone sells them anymore though, it's all LED now so....

    Your project is inspiring and it gave me some new ideas now that I've decided to keep the amps so , thanks Smile
    KenGaler
    KenGaler

    Posts : 76
    Join date : 2019-10-11

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    Post by KenGaler on Sat Dec 21, 2019 12:27 pm

    Dahlberg wrote:A couple of halogen flood lights gets pretty hot. Don't know if anyone sells them anymore though, it's all LED now so....


    Good thought, I'll run down to home depot and see what they have.

    Your project is inspiring and it gave me some new ideas now that I've decided to keep the amps so , thanks Smile

    I wish I thought to add VU meters.
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    audiobill

    Posts : 421
    Join date : 2014-03-13
    Location : Albany, NY

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    Post by audiobill on Sun Dec 22, 2019 12:20 pm

    In the winter, I've sprayed warm transformers in the cold garage, then brought inside to dry.

    Repeat for 2-3 coats.

    KenGaler
    KenGaler

    Posts : 76
    Join date : 2019-10-11

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    Post by KenGaler on Thu Jan 09, 2020 12:59 pm

    I wound up having a freak warm day and got the trannys painted. Also, I got the machined parts in. I cleaned them up, sanded and then used Scotch Brite and WD-40 to brush them. They're presently at the plating co getting a Chromate Clear. I should have them tomorrow or Monday.

    Finally, the most fun part is about here, the wiring. :-)
    KenGaler
    KenGaler

    Posts : 76
    Join date : 2019-10-11

    M-125 Build - Page 2 Empty AC Control Unit

    Post by KenGaler on Tue Jan 14, 2020 11:56 am

    The machined parts are back.  Pics of the AC Control Unit.  

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    M-125 Build - Page 2 Finished-AC-Unit-Low

    M-125 Build - Page 2 Finished-AC-unit-rear
    KenGaler
    KenGaler

    Posts : 76
    Join date : 2019-10-11

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    Post by KenGaler on Thu Jan 16, 2020 11:46 am

    Finally ready for wiring but I really need to work on customers projects for a bit before they dis-own me. This project is addictive.

    M-125 Build - Page 2 Chassis-pre-wring-top

    M-125 Build - Page 2 Chassis-pre-wiring-bottom
    KenGaler
    KenGaler

    Posts : 76
    Join date : 2019-10-11

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    Post by KenGaler on Thu Jan 16, 2020 1:37 pm

    Because I made so many mods I really can't use Bob's excellent wiring instructions. I'll wire both amps at the same time, in layers starting with the most unlikely-to-be-changed parts first such as filaments, Bias meter, fan, primary, output.. then work my way up to the signal lines. I'll yellow line the schematic as I go.
    Dahlberg
    Dahlberg

    Posts : 132
    Join date : 2016-09-27
    Age : 59
    Location : Sweden

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    Post by Dahlberg on Thu Jan 16, 2020 7:04 pm

    Beautiful work so far Very Happy The TDK/Epcos caps needs a couple of days to settle, say 50-100h or so. I replaced the "two cap arrangement" for two of these instead (600v/220uf) and it worked out just fine.
    KenGaler
    KenGaler

    Posts : 76
    Join date : 2019-10-11

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    Post by KenGaler on Sat Jan 18, 2020 11:13 am

    Dahlberg wrote:Beautiful work so far Very Happy  The TDK/Epcos caps needs a couple of days to settle, say 50-100h or so. I replaced the "two cap arrangement" for two of these instead (600v/220uf) and it worked out just fine.

    Thank you
    KenGaler
    KenGaler

    Posts : 76
    Join date : 2019-10-11

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    Post by KenGaler on Sat Jan 18, 2020 11:14 am

    All nets except the signal lines.

    M-125 Build - Page 2 Wiring-before-signals
    KenGaler
    KenGaler

    Posts : 76
    Join date : 2019-10-11

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    Post by KenGaler on Thu Jan 23, 2020 4:10 pm

    All wired!
    Made some changes.  

    - The retro cloth wire is nice but doesn't work for the heater wiring.  Too bulky.
    - I'm not planning on ever using a tube rectifier so I removed the white heater wires and terminated.
    - After a lot of thought and talks with a couple audio mentors I removed the audio GND from the chassis and tied it to Chassis GND via a 10 ohm resistor.  (See section 9 here https://sound-au.com/earthing.htm#s6 )

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