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    VTA M-125 in custom chassis

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    VTA M-125 in custom chassis

    Post by Guest on Mon Sep 08, 2014 8:49 pm

    My version of the M125 getting close to first power up!
    Front face panel will have a mini retro look VU meter. I will be using 4x KT120's, the transformers are currently being sprayed satin black.

     photo fats2_zps85d4642e.jpg

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    carpenter

    Posts : 4
    Join date : 2014-08-20

    Re: VTA M-125 in custom chassis

    Post by carpenter on Tue Sep 09, 2014 5:06 am

    Lovely! I love how you drilled your vent holes with such precision. Now you need a front/side view of the chassis.

    I've been thinking of using star or hex bolts to avoid that cluttered look of misaligned screw heads.

    I'm also considering placing the speaker ground post in between the 4 ohm and 8 ohm posts. That way, all I have to do is flip the speaker's banana jack 180 degrees to alternate between 4 or 8 ohms.

    mazeeff

    Posts : 122
    Join date : 2014-01-06
    Age : 61
    Location : Grand Rapids, Michigan, USA

    Re: VTA M-125 in custom chassis

    Post by mazeeff on Tue Sep 09, 2014 5:40 am

    Tell us more about that little mini-fan. How are you powering it?

    Mike

    Guest
    Guest

    Re: VTA M-125 in custom chassis

    Post by Guest on Tue Sep 09, 2014 8:40 am

    carpenter wrote:Lovely! I love how you drilled your vent holes with such precision. Now you need a front/side view of the chassis.

    I've been thinking of using star or hex bolts to avoid that cluttered look of misaligned screw heads.

    I'm also considering placing the speaker ground post in between the 4 ohm and 8 ohm posts. That way, all I have to do is flip the speaker's banana jack 180 degrees to alternate between 4 or 8 ohms.

    I wish I could take credit on the plate drilling....but alas....I cannot, it is all professionally done on a CNC milling machine by Front Panel Express. I could never do such precision work.
    I will take the credit for designing the layout though and laying out the vent holes Smile
    The front panel too is all done, I am still waiting on the gauges etc., once I have those will take more photo's.
    The transformers have been painted and I 'll be able to mount those later today and start on the wiring.

    Guest
    Guest

    Re: VTA M-125 in custom chassis

    Post by Guest on Tue Sep 09, 2014 8:47 am

    mazeeff wrote:Tell us more about that little mini-fan. How are you powering it?

    Mike

    the ones I use are a mini 12VDC unit, I buy them in bulk from Hong Kong. At full 12V, they are not the quietest, so I have made up a very simple variable DC power supply using an LM317 regulator, in a TO220 package, and drive them at about 8VDC, I found at that setting they are very quiet and still move plenty of air. Being a variable power supply, I can fine adjust that fan supply voltage to arrive at the best/least 'noise setting'.
    I use a mini fully encapsulated transformer for the 15VAC supply, that same transformer also supplies the VU meter driver board.
    I am using the fans to push air into the chassis. Hot tubes, by the nature of heat, draw air 'out' of a chassis through vent holes, that small fan supplies cooler ambient air into the chassis to aid in the tube cooling.

    MarcVBelgium

    Posts : 83
    Join date : 2013-12-06
    Age : 63
    Location : Antwerp, BELGIUM

    M-125 in custom chassis

    Post by MarcVBelgium on Tue Sep 09, 2014 11:16 am

    This work is just BEAUTIFUL

    Congrats on the work so far..... it's a great job!

    Bob Latino
    Admin

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    Join date : 2008-11-26
    Location : Massachusetts

    Re: VTA M-125 in custom chassis

    Post by Bob Latino on Tue Sep 09, 2014 11:27 am

    Holger,

    Excellent work on that custom version of the VTA M-125 monoblock amp. Yes - post up a photo of the wiring when you get the amp wired ..

    Bob

    audiobill

    Posts : 270
    Join date : 2014-03-13
    Location : Philadelphia

    Re: VTA M-125 in custom chassis

    Post by audiobill on Tue Sep 09, 2014 4:30 pm

    Is that the "soft start" board I see in there?

    Guest
    Guest

    Re: VTA M-125 in custom chassis

    Post by Guest on Tue Sep 09, 2014 4:32 pm

    audiobill wrote:Is that the "soft start" board I see in there?

    it is indeed, I believe that is a great addition to any tube amp in extending power tube life, and the extra cost is minimal

    Guest
    Guest

    Re: VTA M-125 in custom chassis

    Post by Guest on Mon Sep 15, 2014 9:26 pm

    well, the beasty is alive...and sounds just so wonderful!...I had the volume pot wired the wrong way, nearly blew the test speakers off the wall!!!!!!!...not to mention my eardrums!!
    Powere straight up, no worries.

    The wiring is still somewhat temp, I am waiting for the correct handed front panel, the one in the photo is for a 'left handed' chassis, the amp in the photo is actually a 'right handed' chassis.

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     photo bbopper1_zpsd78beff7.jpg

    colin86325

    Posts : 41
    Join date : 2014-04-01

    Re: VTA M-125 in custom chassis

    Post by colin86325 on Tue Sep 16, 2014 6:43 am

    She's a beauty!
    On a side note, would there be an improvement if you clocked one of the chokes 90 degrees?

    Bob Latino
    Admin

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    Re: VTA M-125 in custom chassis

    Post by Bob Latino on Tue Sep 16, 2014 9:21 am

    colin86325 wrote:She's a beauty!
    On a side note, would there be an improvement if you clocked one of the chokes 90 degrees?

    The chokes are mainly passing DC .. They are there to "choke off" small amounts of AC riding on the DC before the audio signal is dropped onto the DC B+. Because almost no AC is passing through the choke, there is virtually no interaction either between the two chokes or between the chokes and the power transformer.

    Bob

    Guest
    Guest

    Re: VTA M-125 in custom chassis

    Post by Guest on Tue Sep 16, 2014 9:28 am

    Bob Latino wrote:
    colin86325 wrote:She's a beauty!
    On a side note, would there be an improvement if you clocked one of the chokes 90 degrees?

    The chokes are mainly passing DC .. They are there to "choke off" small amounts of AC riding on the DC before the audio signal is dropped onto the DC B+. Because almost no AC is passing through the choke, there is virtually no interaction either between the two chokes or between the chokes and the power transformer.

    Bob

    you took the words right out of my mouth! :-)

    PeterCapo

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    Join date : 2008-12-05

    Re: VTA M-125 in custom chassis

    Post by PeterCapo on Tue Sep 16, 2014 3:27 pm

    Very nice!

    colin86325

    Posts : 41
    Join date : 2014-04-01

    Re: VTA M-125 in custom chassis

    Post by colin86325 on Tue Sep 16, 2014 4:15 pm

    Ah, good to know Smile

    mantha3

    Posts : 298
    Join date : 2010-11-10

    Re: VTA M-125 in custom chassis

    Post by mantha3 on Tue Sep 16, 2014 7:59 pm

    Excellent Job. Get a shot of the two side by side when you are done

    Guest
    Guest

    Re: VTA M-125 in custom chassis

    Post by Guest on Fri Sep 19, 2014 8:24 pm

    OK, here are shots of the finished unit. This is the 'right handed' version, I have added a 'left handed' version, but I cheated, by just 'mirroring' the right hand version.

     photo bbopperrh1_zps17abf83a.jpg

    right handed version

     photo bbopperlh_zpsa9f79d52.jpg

    left handed version

     photo bbopperrh2_zps776956bc.jpg

     photo bbopperrh4_zps7bd53892.jpg

     photo bbopperrh6_zpsd510d0c0.jpg

     photo bbopperrh7_zpsa5d01546.jpg


    Guest
    Guest

    Re: VTA M-125 in custom chassis

    Post by Guest on Mon Oct 13, 2014 5:42 pm

    here are 'both' handed versions, in a different wooden chassis

     photo BBopper21_zpsdbade123.jpg

    Bob Latino
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    Re: VTA M-125 in custom chassis

    Post by Bob Latino on Mon Oct 13, 2014 7:20 pm

    Nice work Holger ..

    mantha3

    Posts : 298
    Join date : 2010-11-10

    Re: VTA M-125 in custom chassis

    Post by mantha3 on Mon Oct 13, 2014 7:21 pm

    NICE!!!!

    mantha3

    Posts : 298
    Join date : 2010-11-10

    Re: VTA M-125 in custom chassis

    Post by mantha3 on Mon Oct 13, 2014 7:29 pm

    PS - I have the same VU meter kit in a preamp I built. It is nice. I did have a problem with the body of the meter breaking from the face. I got a replacement and ran a bit of epoxy where the body fits to the face to reinforce.

    You may want buy a back up pair of meters just in case.

    Guest
    Guest

    Re: VTA M-125 in custom chassis

    Post by Guest on Mon Oct 13, 2014 11:07 pm

    mantha3 wrote:PS - I have the same VU meter kit in a preamp I built.  It is nice.  I did have a problem with the body of the meter breaking from the face.  I got a replacement and ran a bit of epoxy where the body fits to the face to reinforce.  

    You may want buy a back up pair of meters just in case.  

    thanks for the heads up, will keep an eye on them and yes, I do have plenty of spares!

    wgallupe

    Posts : 85
    Join date : 2014-05-18
    Age : 62
    Location : Central Mass.

    Re: VTA M-125 in custom chassis

    Post by wgallupe on Tue Oct 14, 2014 8:20 am

    Those are beautiful!

    deepee99

    Posts : 1337
    Join date : 2012-05-23
    Location : Wallace, Idaho

    Re: VTA M-125 in custom chassis

    Post by deepee99 on Tue Oct 14, 2014 3:13 pm

    wgallupe wrote:Those are beautiful!
    Yup.

    thompson12

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    Age : 55
    Location : Lehigh valley pa

    Re: VTA M-125 in custom chassis

    Post by thompson12 on Sun Dec 06, 2015 6:52 pm

    Did you connect the VU meters on you amp if so how

    thanks Mitch

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