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    My KT120 / M-125's

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    Dahlberg

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    Re: My KT120 / M-125's

    Post by Dahlberg on Thu Nov 03, 2016 1:41 pm

    It's coming along  Smile

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    LeGrace

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    Re: My KT120 / M-125's

    Post by LeGrace on Thu Nov 03, 2016 3:20 pm

    Love your carpentry skills!
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    Dahlberg

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    Re: My KT120 / M-125's

    Post by Dahlberg on Thu Nov 03, 2016 5:32 pm

    Thanks, some decent tools helps a lot Smile I decided on a very simple profile and
    just added a 45° angle over the corners to make them a bit more durable.
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    LeGrace

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    Re: My KT120 / M-125's

    Post by LeGrace on Thu Nov 03, 2016 6:00 pm

    Dahlberg wrote:Thanks, some decent tools helps a lot Smile I decided on a very simple profile and
    just added a 45° angle over the corners to make them a bit more durable.

    My attempt at doing mitered corners was a total fail. Yours look amazing!
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    Dahlberg

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    Re: My KT120 / M-125's

    Post by Dahlberg on Thu Nov 03, 2016 7:02 pm

    Well without the tools it just doesn't work. Hard enough with them.
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    Dahlberg

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    Re: My KT120 / M-125's

    Post by Dahlberg on Thu Nov 03, 2016 7:23 pm

    This is my dsp xo, no mitred corners and usually turns out good looking.

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    Kentley

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    Re: My KT120 / M-125's

    Post by Kentley on Thu Nov 03, 2016 10:21 pm

    That is simply stunning, sir. The wood knob is superb. All my hats are off. I'm running out of hats.
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    Dahlberg

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    Re: My KT120 / M-125's

    Post by Dahlberg on Fri Nov 04, 2016 3:53 am

    Thanks. To bad I have to build a new one Cool The first one has two hardwired "Unballancers" but
    I'm rebuilding for tubes on all outputs using the pcb's from John Broskie.
    Then there is just not enough space. The sub output is opamp based today and I also had
    the possibility to run a second identical opamp buffer for mid bass for a while, but the
    "Unballancer" came out such a strong solution that I decided to use that for the sub region as well.
    It's all based around the "Najda" dsp and three separate "BuffaloIII" dacs.
    Twisted pear is releasing the "BuffaloIV" using the new "Ess 9038pro" chip in the hopefully not
    so distant future and I'm waiting for the 8-channel version of that dac, the project is on
    a stand still for now. The surprisingly strong result from the output buffer shootout was one of
    the reasons that I decided to try a tube power amp solution in that region as well.

    It's not possible for the sub section though.

    Edit: Picture

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    aguaazul

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    Location : Livermore, CA

    Re: My KT120 / M-125's

    Post by aguaazul on Mon Nov 07, 2016 3:18 am

    Looking good all around!  I'd be interested in looking at the full build history on your DAC solutions if you don't mind sharing.

    Cheers,

    Blue
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    Dahlberg

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    Re: My KT120 / M-125's

    Post by Dahlberg on Mon Nov 07, 2016 6:56 am

    aguaazul wrote:Looking good all around!  I'd be interested in looking at the full build history on your DAC solutions if you don't mind sharing.

    Cheers,

    Blue

    If you do a Google picture search for "najda dahlberg dsp" you will find most of the
    information (at diyaudio). The "Najda thread" is a bit hard to read through (300+ pages)
    but with the pictures to go from you would start at the more relevant pages.

    For information about the new solution a good place to start would be the unbalancer manual.

    http://glass-ware.com/User_Guides/Unbalancer%209-pin%20-PS.pdf

    The "BuffaloIV" doesn't exist yet but the "buffaloIIIse" is what I have been using up till now.

    http://twistedpearaudio.com/digital/buffalose.aspx

    And since this is a picture thread about the M-125 Embarassed Smile

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    LeGrace

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    Re: My KT120 / M-125's

    Post by LeGrace on Tue Nov 08, 2016 2:30 pm

    Mad wiring skills Shocked
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    Dahlberg

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    Re: My KT120 / M-125's

    Post by Dahlberg on Tue Nov 08, 2016 7:49 pm

    Don't know about that, but hopefully it will work when it's done.
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    tubes4hifi
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    Re: My KT120 / M-125's

    Post by tubes4hifi on Sun Nov 13, 2016 3:37 pm

    I tend to keep my oven around 200-225 to cure paint, not any higher, and usually 15-20 minutes is plenty
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    Dahlberg

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    Re: My KT120 / M-125's

    Post by Dahlberg on Sun Nov 13, 2016 6:06 pm

    Well the next time I will use spraypaint I will be more careful with temperature. Bad news about the powder coating as well.
    The "candy gold" didn't turn out good at all and the paintguy thought it was a problem with the powder itself.
    So now there is a new colour in the making. Candy red this time, a quite dark one.


    Last edited by Dahlberg on Thu Nov 17, 2016 9:36 am; edited 1 time in total
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    Dahlberg

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    Re: My KT120 / M-125's

    Post by Dahlberg on Thu Nov 17, 2016 9:35 am

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    Dahlberg

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    Re: My KT120 / M-125's

    Post by Dahlberg on Sat Nov 19, 2016 11:09 am

    I could not help myself so I had to see how it looked with tubes in place. It turns out a bit lighter on camera then it looks.  Very Happy

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    LeGrace

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    Re: My KT120 / M-125's

    Post by LeGrace on Sat Nov 19, 2016 3:40 pm

    Stunning! What did you do with the power switch? Have you considered brass plaques for the front?
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    Dahlberg

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    Re: My KT120 / M-125's

    Post by Dahlberg on Sat Nov 19, 2016 5:22 pm

    The power switch is on the back, you can see part of it on an earlier picture. I'm not planning for any brass plaque, hmmm.
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    Dahlberg

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    Re: My KT120 / M-125's

    Post by Dahlberg on Wed Jan 04, 2017 9:03 am

    Got them fired up yesterday, and got some slight hum. Trying a screened feedback cable today to see if that solves it. Got a tip at diyaudio from a Canadian guy who had the same issue, apart from that it was a rawing review Smile Mine sounds promising Smile
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    vtshopdog

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    Re: My KT120 / M-125's

    Post by vtshopdog on Wed Jan 04, 2017 10:42 pm

    Dahlberg wrote:Got them fired up yesterday, and got some slight hum. Trying a screened feedback cable today to see if that solves it. Got a tip at diyaudio from a Canadian guy who had the same issue, apart from that it was a raving review Smile Mine sounds promising Smile

     Do I understand correctly that you are replacing the yellow(usually?) wire that runs from the O.T. to PCB with a splice of shielded cable?

    Beautiful build BTW
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    Dahlberg

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    Re: My KT120 / M-125's

    Post by Dahlberg on Thu Jan 05, 2017 10:32 am

    vtshopdog wrote:
    Dahlberg wrote:Got them fired up yesterday, and got some slight hum. Trying a screened feedback cable today to see if that solves it. Got a tip at diyaudio from a Canadian guy who had the same issue, apart from that it was a raving review Smile Mine sounds promising Smile

    Do I understand correctly that you are replacing the yellow(usually?) wire that runs from the O.T. to PCB with a splice of shielded cable?

    Beautiful build BTW

    Thanks Smile
    Yes it's the yellow one. I cut it short just leaving a few centimeters for connetion to a screened
    cable that I connected to the pcb. The screen is only connected to ground at the input board.
    I'm using twisted wire for the line level input, maybe a screened cable would be an idea there as well Idea

    So first initial listening impression Cool

    I really like the synergy they create with my 300b amps. Everything just seems to fit better together
    resulting in a more relaxed and natural listening experience. I have a gain structure that is based
    on the possibility to go to full blast without distroying anything and full blast now feels less loud (less distortion?).
    Wood intruments and percusion sounds more natural, the lower notes on saxophone are just fenomenal.
    Dynamics are at least as good as earlier or even better, I'm leaning to the second on that.
    For now the only thing that could use some attention is the lowest bass region, where they leave over to
    the subs. It seems that I have lost some definition in that area. Maybe another rectifier solution and also try the 8 ohm tap ?

    I'm only using them from 65-350hz.
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    Dahlberg

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    Re: My KT120 / M-125's

    Post by Dahlberg on Mon Jan 09, 2017 11:46 am

    There are some small adjustments left but it's slowly coming in to place Very Happy



















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    Dahlberg

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    Re: My KT120 / M-125's

    Post by Dahlberg on Tue Jan 10, 2017 12:10 pm

    So now the feedback wire is relocated as described in the picture and I
    measured 3,5mV ac of the speaker connections. The lowest value measured
    so far Smile  The remaining audible hum is almost non existant and I'm not going
    to loose any sleep over it. In due time I will try some other tubes for input.
    I'm using 5814A tubes for now, no idea if they are noisy or not.

    Only difference is that in my amps the wire comes closer to the bottom of the cabinet.
    Thanks to Bob and some other guy at DIYAUDIO for pointing this out. Smile



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    pedrocols

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    Re: My KT120 / M-125's

    Post by pedrocols on Tue Jan 10, 2017 6:41 pm

    Very nice! I have mine for a little over two years now and still running strong. I suspect I will have to shortly get some new tubes.
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    Dahlberg

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    Re: My KT120 / M-125's

    Post by Dahlberg on Tue Jan 10, 2017 7:44 pm

    Thanks, I'm doing some evaluation regarding what output tap to use. Tomorrow.

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