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


    Woody/Glass/Copper M125 build

    Share

    vtshopdog

    Posts : 60
    Join date : 2015-07-11
    Location : UT, USA

    Woody/Glass/Copper M125 build

    Post by vtshopdog on Fri Dec 04, 2015 7:17 pm

     photo IMG_1888_zps81lnzcq6.jpg

    My snail pace M125 build is finally functional, sounds nice, still dialing and breaking it in plus fumbling around with assorted driver tubes (will have some spare GE 12bh7's - PM me if interested)  Dragged this out for almost 6 months, but there was never any intention of trying to move fast.  Long and winding road lead me to actually finish the wood TT plinth started 14 months ago plus collect and organize all the cabling behind my cabinet (Ha ha - the extra monoblock AC cord broke my threshold for cable clutter)

    I made a handful of cosmetic (W.A.F. = thumbs up!!) and chassis modifications:

    A dozen or so 1/4" vent holes in bottom chassis pan, one centered under each tube and others at corners.
    Bolt on aluminum feet in place of stick on rubber.
    Filtered IEC socket
    Teflon silver plate wire
    4 & 8 ohm output binding posts and some AudioPhool RCA plugs
    Glass panel to cover driver board (total P.I.T.A. !!  Failed my DIY glass fab attempt - needed to be rescued by professionals at local glass shop ...)
    Wood "fenders" on the sides and a copper strip on front bottom to cover chassis seams.
    Stainless hardware for tranny bell covers, defaulted to metallic black paint after mocking up with several colors.
    Shot some metallic silver that was leftover from my TT rebuild over self etching primer on the quad caps - turned out surprisingly nice to my eye as the raw cap is, well, raw.

    Thanks to Bob for ridiculously fast response to my occasional questions.

    Cheers, Tim


     photo IMG_1889_zpsnr2wiu0f.jpg

     photo IMG_1876_zps9igdgbnf.jpg

     photo IMG_1887_zpsj79ko29e.jpg

     photo BOTTOM_zps0kbupprp.jpg

    pedrocols

    Posts : 62
    Join date : 2014-11-24
    Location : Western MA

    Re: Woody/Glass/Copper M125 build

    Post by pedrocols on Fri Dec 04, 2015 7:28 pm

    I like it a lot!

    PeterCapo

    Posts : 380
    Join date : 2008-12-05

    Re: Woody/Glass/Copper M125 build

    Post by PeterCapo on Fri Dec 04, 2015 8:01 pm

    Very nice work.

    Kentley

    Posts : 300
    Join date : 2015-03-06
    Age : 64
    Location : Worcester, MA

    Re: Woody/Glass/Copper M125 build

    Post by Kentley on Fri Dec 04, 2015 8:25 pm

    I love three things about these:
    The meticulous build quality under the hood.
    The quad cap finish.
    The exquisite touch of the copper strip.
    Bravissimo!!!

    Maintarget

    Posts : 208
    Join date : 2013-02-10

    Re: Woody/Glass/Copper M125 build

    Post by Maintarget on Fri Dec 04, 2015 8:28 pm

    Very Impressive build, simple yet elegant touches that really make it your own, Nice work!!!

    vtshopdog

    Posts : 60
    Join date : 2015-07-11
    Location : UT, USA

    Re: Woody/Glass/Copper M125 build

    Post by vtshopdog on Fri Dec 04, 2015 8:53 pm

    Kentley wrote:I love three things about these:
    The meticulous build quality under the hood.

    Umm, maybe:
    If you look closely at photo you will see that amp has inverted polarity on the input wires.  Color coded wire made the brain fart easier to find though.  These were literally the last two solder connections I made in the entire project (hey, it was late!)  

    That amp no make'em sound, only weak cross talk if I cranked up volume.  After 6 months assembly I was literally plugging them in for first time just as some house and dinner guests came in the door - (PANIC - marginally social nerd wants to go in basement and mess with his electronics stuff when we have company . . . . . )

    Two weeks later when I finally installed the wood sides one of the mounting screws cut the insulation on the input wire on the other amp effectively duplicating the issue by grounding signal to chassis.  That amp stop make'em sound too

    pedrocols

    Posts : 62
    Join date : 2014-11-24
    Location : Western MA

    Re: Woody/Glass/Copper M125 build

    Post by pedrocols on Fri Dec 04, 2015 8:56 pm

    I would definitely buy a pair of the "wood fenders" from you if you make me some!

    sKiZo

    Posts : 1287
    Join date : 2013-04-01
    Location : Michigan USA

    Re: Woody/Glass/Copper M125 build

    Post by sKiZo on Fri Dec 04, 2015 9:10 pm

    Lookin' FINE!

    Good match for the rest of your equipment too. That's always a nice touch.

    Wanna have some fun once you get em burned in - tape over the holes in the bottom plate and take temp readings on both ... I think you'll be surprised at how much those holes drop the operating temperatures. Bonus points if you report back on the results.

    skriefal

    Posts : 116
    Join date : 2011-09-20
    Location : Utah, USA

    Re: Woody/Glass/Copper M125 build

    Post by skriefal on Fri Dec 04, 2015 10:31 pm

    I'm no longer the only owner of M-125s in Utah?  Smile

    Looks good!

    Bob Latino
    Admin

    Posts : 2378
    Join date : 2008-11-26
    Location : Massachusetts

    Re: Woody/Glass/Copper M125 build

    Post by Bob Latino on Sat Dec 05, 2015 9:35 am

    Nice job Tim .. The glass covers for the driver boards and those wooden side "fenders" really make your amps unique ..

    Bob

    vtshopdog

    Posts : 60
    Join date : 2015-07-11
    Location : UT, USA

    Re: Woody/Glass/Copper M125 build

    Post by vtshopdog on Sat Dec 05, 2015 1:59 pm

    sKiZo wrote:Lookin' FINE!

    Good match for the rest of your equipment too. That's always a nice touch.

    Wanna have some fun once you get em burned in - tape over the holes in the bottom plate and take temp readings on both ... I think you'll be surprised at how much those holes drop the operating temperatures. Bonus points if you report back on the results.

    Covering the vent holes is a great idea, will try it and post result - I'm kind of curious to see what the variance is as added them purely to indulge my "belt and suspender" OCD tendencies.  (plus I just plain love cutting operations on 16 ga stainless - NOT!!)

    deepee99

    Posts : 1260
    Join date : 2012-05-23
    Location : Wallace, Idaho

    Re: Woody/Glass/Copper M125 build

    Post by deepee99 on Sat Dec 05, 2015 3:23 pm

    skriefal wrote:I'm no longer the only owner of M-125s in Utah?  Smile

    Looks good!
    Hey, Idaho counts as part of Utah, doesn't it?

    Vtshopdog, agree with all the others. That is one beautiful M-125 build, and a testament to the true OCD nature of the tube audiophile.

    skriefal

    Posts : 116
    Join date : 2011-09-20
    Location : Utah, USA

    Re: Woody/Glass/Copper M125 build

    Post by skriefal on Sun Dec 06, 2015 12:25 pm

    deepee99 wrote:
    Hey, Idaho counts as part of Utah, doesn't it?

    Close enough!

    MontanaWay

    Posts : 767
    Join date : 2014-02-06
    Age : 58
    Location : Cameron, Montana

    Re: Woody/Glass/Copper M125 build

    Post by MontanaWay on Sun Dec 06, 2015 6:58 pm

    that is a brilliant build!
    Awesome!

    vtshopdog

    Posts : 60
    Join date : 2015-07-11
    Location : UT, USA

    Re: Woody/Glass/Copper M125 build

    Post by vtshopdog on Sun Dec 06, 2015 7:47 pm

    skriefal wrote:I'm no longer the only owner of M-125s in Utah?  Smile

    Maybe....

    Blowing smoke about building myself - I actually bought them for $50 from a homeless guy in Pioneer Park - you better go check your equipment rack......

    vtshopdog

    Posts : 60
    Join date : 2015-07-11
    Location : UT, USA

    Re: Woody/Glass/Copper M125 build

    Post by vtshopdog on Sun Dec 06, 2015 7:52 pm

    MontanaWay wrote:that is a brilliant build!
    Awesome!

    I got lots of ideas from looking your gear - its all gorgeous  

    Really wanted VU meters, but no way taking on the task of making big holes in 16ga stainless.  Stuff is tough as nails - wrecked a $35 bit on my power nibbler just enlarging output post holes 12mm each

    deepee99

    Posts : 1260
    Join date : 2012-05-23
    Location : Wallace, Idaho

    Re: Woody/Glass/Copper M125 build

    Post by deepee99 on Sun Dec 06, 2015 7:53 pm

    vtshopdog wrote:
    MontanaWay wrote:that is a brilliant build!
    Awesome!

    I got lots of ideas from looking your gear - its all gorgeous  

    Really wanted VU meters, but no way taking on the task of making big holes in 16ga stainless.  Stuff is tough as nails - wrecked a $35 bit on my power nibbler just enlarging output post holes 12mm each

    That's why God invented machine shops!

    vtshopdog

    Posts : 60
    Join date : 2015-07-11
    Location : UT, USA

    Re: Woody/Glass/Copper M125 build

    Post by vtshopdog on Fri Dec 11, 2015 9:15 pm

    sKiZo wrote:Wanna have some fun once you get em burned in - tape over the holes in the bottom plate and take temp readings on both ... I think you'll be surprised at how much those holes drop the operating temperatures. Bonus points if you report back on the results.

    Ok took a stab at this last few days by covering my 12 added 1/4" vent holes on one amp.  
    First up, my Harbor Freight laser IR thermometer does not deal with glossy surfaces very well and measurements on tubes were not very consistent.  (the instructions suggest applying a piece of duct tape to objects to be measured "making sure to allow enough time for the tape to reach ambient temperature")(I'm fresh out of high temp duct tape, so didn't go there)

    After some futzing, developed a way to get semi consistent measurements on tubes, so give or take here is what I found:

    Transformers and driver board - no real difference
    Front power tubes - about 3-5 F cooler with venting
    Rear power tubes - 10-12 F cooler
    WZ68 - 8-10 F cooler
    Quad cap 3-5 F cooler
    Chassis - Power tube area was about 5-8 F cooler, no real difference elsewhere

    One thing of note is that the differential tended to increase when amps were driven harder and generating more heat.  No surprise as adding some venting at the margins will likely help as things tend to get warm and speed of air travel in convection increases.

    All in all a simple mod if you have a drill press.  (tip - go buy a new black oxide or HSS bit, avoid Ti coated bits for SS as they seem to cut very poorly)

    Sponsored content

    Re: Woody/Glass/Copper M125 build

    Post by Sponsored content Today at 9:29 pm


      Current date/time is Fri Sep 30, 2016 9:29 pm