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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


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jhoak
davidness
Sal
hawaii.ken
baddog1946
Bob Latino
TMadden
jjones3318
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    Custom M125's

    jjones3318
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    Post by jjones3318 Mon Mar 05, 2012 12:08 am

    I thought I'd post some pics of a pair of custom M125's I'm working on. This is a mirrored design using cherry and aluminum (from FPE) chassis. The bias meters aren't hooked up yet - haven't decided how I want to do it.

    The rest of the system - phono pre, line pre, and separate PSU's for each are of the same design. I'll post pictures of those as I finish them.

    The empty cavity on the face is for an etched brass piece I haven't finished yet.

    What great sound from these amps! They are dead quiet also.

    Custom M125's P1060610
    Custom M125's P1060569
    Custom M125's P1060603
    Custom M125's P1060647
    Custom M125's P1060564
    TMadden
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    Post by TMadden Mon Mar 05, 2012 4:44 am

    Beautiful Work!
    Bob Latino
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    Post by Bob Latino Mon Mar 05, 2012 4:54 am

    Hi John,

    That is one of the best custom builds of a tube amp kit that I have ever seen. You can tell that a lot of thought beforehand and many hours of labor went into the construction your amps. Wow !

    Bob
    baddog1946
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    Post by baddog1946 Mon Mar 05, 2012 6:10 am

    Wow is right!
    What a beautiful job on those 125's. Looks like maple wood chassis sides. Very thoughtful design and the workmanship is excellent. Congratulations!
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    Post by Guest Mon Mar 05, 2012 7:37 pm

    Man those look great - you should definitely think about packaging it as an upgrade - I know I would be interested.
    hawaii.ken
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    Post by hawaii.ken Tue Mar 06, 2012 12:30 am

    WOW!!
    Sal
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    Post by Sal Tue Mar 06, 2012 7:57 am

    Exceptional build quality! Nice upgraded chassis's. A labor of love!

    Sal
    davidness
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    Post by davidness Tue Mar 06, 2012 9:13 am

    I would seriously buy a pair of those from you, assuming you can come up with a way to offer bias selector for the meter, and the price were right. If this is something you'd consider, drop me note. Either as a kit or assembled.


    Last edited by davidness on Tue Mar 06, 2012 11:05 am; edited 1 time in total
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    Post by jhoak Tue Mar 06, 2012 11:03 am

    Still thinking about replacing your VRDs David?
    davidness
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    Post by davidness Tue Mar 06, 2012 11:07 am

    I would trade, even money, my VRD-ST for a pair of these custom M125's. I might even contribute some extra cash.
    mantha3
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    Post by mantha3 Tue Mar 06, 2012 12:43 pm

    I stop into this forum mainly hoping to see posts like this. Well done man
    jjones3318
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    Post by jjones3318 Wed Mar 07, 2012 9:37 am

    Wow - thanks for the kind words. Sorry I've been away - I have to get the rest of the system finished and shipped off by Monday, so I've been heads-down on that.

    I haven't considered kits or selling these. Frankly, they are far to labor intensive and costly with the custom machined pieces (around $1K), and doing the aluminum inlays by hand (x-acto knife and dremel) isn't fun. Especially when you're doing 23 of them.

    The entire design is based on the preamp design, which has been evolving in my head for the past six months. Hopefully that goes well and I can get some pictures up soon.

    mantha3
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    Post by mantha3 Thu Mar 08, 2012 12:45 pm

    Umm, why ya building 23 of em? selling these?
    jjones3318
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    Post by jjones3318 Fri Mar 09, 2012 1:18 am

    23 inlays - not 23 amps. I may build another pair for me, but that'd be it.
    jjones3318
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    Post by jjones3318 Fri Mar 16, 2012 11:33 pm

    I hope to have better pics in the next week or so, but here's what I have now. This first shot is the entire system.

    Custom M125's Img_3712


    This is the line preamp. The small knob on the left is the source selector, and the one on the right is mono, mute, and stereo. There are 2mm LED's for the volume indicators - these are green, orange, or red depending on the level.

    Custom M125's P1060675


    And this last is the preamp power supply - completely independent supplies for each channel. The heaters use a separate transformer located in the chassis and a symmetrical supply. This is overkill, but some aspects of the system were more show than go.

    Custom M125's Photo1
    jjones3318
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    Post by jjones3318 Wed Mar 21, 2012 10:50 am

    To close this out, here's what this was all about: The Knittel Lounge
    Tube Nube
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    Post by Tube Nube Wed Mar 21, 2012 1:20 pm

    Nicely done!
    sKiZo
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    Post by sKiZo Tue Jul 02, 2013 11:09 am

    wOw ... just ... wOw ... well worthy of a bump in case anyone missed it the first time around.

    Beautiful work. One question though ... what's this then?

    Custom M125's Ps-filter

    I figure either a filter or step down for the time delay board?
    jjones3318
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    Post by jjones3318 Tue Jul 02, 2013 12:05 pm

    Just a relay.  I used real Bulgin non-latching switches for power and Ti's driver board for the switch: http://www.amb.org/audio/epsilon24/.  The un-insulated connections are on the LV side.  They should be insulated but I didn't have time - I built the entire system; 6 custom chassis, the design of over 30 custom metal pieces, the art on the brass memorial badges, rebuilt the turntable, etc. in 30 days.  I had the night before to debug it before I had to pack it and next day all ~500 lbs of it to Austin TX.  The speaker cabs were done outside.

    No pressure Smile 

    This pair use GZ33 rectifiers so there's no need for a time delay board.  Frankly, I don't believe in time delay circuits anyway - I've never seen proof of cathode stripping on anything less than transmitter tubes running at multi-KV voltages.  This system was built as a memorial for a co-worker, so it's more show than go.  These days I use well regulated solid state supplies.

    Here's an updated link to the article I wrote on it: http://blog.moodmedia.com/2012/03/sxsw-barry-knittel-lounge/



    JP
    sKiZo
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    Post by sKiZo Tue Jul 02, 2013 12:37 pm

    Aha ... I mistook the board for the TDR that Bob provides as an option. My bad. I went with a latching switch myself, but it has the "halo" led lighting built in. That board might be an elegant option for providing power for the LED while still isolating it from the amp. I understand they can be a bit noisy.

    No pressure ... right. Quite the tribute though ... I can imagine your friend tapping his foot and smiling every time somebody fires up a goodie ...

    Also went wandering thru the website and it looks like you have a fun place to work. One thing caught my eye there ... "in-store media specialist that uses a mix of music, visual and scent media" ... a veritable assault on the senses! Begs the question of what all sorts of augmentation you've added to your own home system ... I've got a lot of lights (old school incandescents, LED lightbars, and the occasional laser or two), but I draw the line on smell-o-vision. Wink
    jjones3318
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    Post by jjones3318 Tue Jul 02, 2013 1:24 pm

    Nah, you're not going to pick up any discernible noise from LEDs, especially in a power amp. The Chinese copies of the Bulgin switches I could get my hands on felt cheap, so I went with the real deal which necessitated the driver board due to using a momentary switch.

    It was a fun place to work. I left in November of last year, shortly after it was sold.

    Currently I'm a bit of a purist with my system - full range speakers, 300B amps, and no preamp aside from the phono stage. I prefer low light, no distractions, and listen with my eyes closed.

    I've enjoyed every piece of gear and every step on my audio journey. I'm not sure where it'll ultimately go, but this stopover works well for me for now.

    peterh
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    Post by peterh Tue Jul 02, 2013 1:59 pm

    jjones3318 wrote:Just a relay.  I used real Bulgin non-latching switches for power and Ti's driver board for the switch: http://www.amb.org/audio/epsilon24/.  The un-insulated connections are on the LV side.  They should be insulated but I didn't have time - I built the entire system; 6 custom chassis, the design of over 30 custom metal pieces, the art on the brass memorial badges, rebuilt the turntable, etc. in 30 days.  I had the night before to debug it before I had to pack it and next day all ~500 lbs of it to Austin TX.  The speaker cabs were done outside.

    No pressure Smile 

    This pair use GZ33 rectifiers so there's no need for a time delay board.  Frankly, I don't believe in time delay circuits anyway - I've never seen proof of cathode stripping on anything less than transmitter tubes running at multi-KV voltages.  This system was built as a memorial for a co-worker, so it's more show than go.  These days I use well regulated solid state supplies.

    Here's an updated link to the article I wrote on it: http://blog.moodmedia.com/2012/03/sxsw-barry-knittel-lounge/



    JP
    Sorry but i do not understand the circuit, is it a momentary switch , then how do one shut off the power ? ( if it's a make/break switch i get the idea)

    jjones3318
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    Post by jjones3318 Tue Jul 02, 2013 2:20 pm

    The driver circuit here http://www.amb.org/audio/epsilon24/ drives a relay. Each momentary contact closure toggles the relay between on and off.

    It's an overly-compicated solution, but was necessary when the Bulgin switches were the only game in town if one wanted that look. Today there are plenty of alternative switches that are copies of the Bulgin look.
    peterh
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    Post by peterh Tue Jul 02, 2013 2:44 pm

    jjones3318 wrote:The driver circuit here http://www.amb.org/audio/epsilon24/ drives a relay.  Each momentary contact closure toggles the relay between on and off.  

    It's an overly-compicated solution, but was necessary when the Bulgin switches were the only game in town if one wanted that look.  Today there are plenty of alternative switches that are copies of the Bulgin look.  
    It's late here ...  But i still don't get the function. The K1 relay is part of overload indicator. Is the external relay ( across D3 ) a toggle-relay ? But then the crydon D1240 has no "toggle" it will turn on at 3-24V and stay on ...
    Am i missing something ?

    Ahhh, i get it, Q2 and Q3 constitutes a bistable flipflop( vippa as we call it). Nice !

    I once made a simular in function but used a 9V battery for "power on", holding was supplied from the amp itself. Thus i saved the constant power and associated transformer. The 9V battery lasted for years and years ...

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