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Luxman DML-02

I got the parts in, but somehow missed ordering the 22K Ohm resistors. So back to mouser for $2.79 in parts.

After building the DML-01 using an SMD for the FET pair and through hole discrete components for the BJT transistor pair and resistors, I thought I could easily hand solder SMD transistor pairs and resistor elements on the DML-02. Wrong. The FET pair was a relatively large component compared to the BJT pair components and resistors. Took me 3 tries and the loss of two components to get the first BJT pair soldered. The resistors were no better but at least I didn't lose any components.

Does anyone know if there are things like a third hand that has at least a micrometer type adjustment for the Z axis? I have gooseneck mounted third hands that are impossible to adjust under the microscope. Also, do they make things such as steady rests for soldering irons? My hands shake enough that it causes a problem when working under a scope.
 
Maybe ask a general question about smd builds in DIY to get answers. Some here have hot air which I think might allow holdingthe component in place while getting it hot enough to solder. Post a pic or two of the task at hand for best responses
 
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Finally built a working module!

An ugly soldering job, but it worked the first time, which is a first for me. The square pins dropped right in the old holes, I didn't have to drill the mounting holes out like I did for the M-12.

I have no way to measure the output in any way to see if it really works properly, all I did was hook it up to my test amp and speakers and listened to it. I just have DACs as input sources so I can't test the phono stage. The noise is gone and the sound level on the left and right channels is equal as best I can tell. My garage amp has VU meters so I could at least visualize something and it looked fine with a 1000Hz test signal.

As everything works now, I don't see any reason to pull the other DMLs. When they fail, it doesn't look like there is a cascade effect. I am going to clean it up and put it all back together and run it for awhile. The faceplate is in poor condition so I am not real motivated to do a lot with this preamp, it was mostly to confirm that I could build a replacement DML-02.
 
That middle pic of the board in the preamp make it look so large the soldering would be easy. But I usually don't see inch long ¼W resistors.

Nice work. Send me a couple, maybe kits, I can give the soldering a try.
 
Blue Shadow said:
This preamp was designed in Luxman's best early era, the time when their 50th Anniversary (1975) Series, the Tim de Paravicini designed M6000 power amp and the matching tuner T-110 and preamp C-1000 (don't know how much work Tim did on these) along with his tube MB3045 power amps. Additionally, their new top of the line gear the Laboratory Reference Series was starting to hit the shelves. The -12 series with the L-10 and L-11 were in their Laboratory Standard Series, their next best products and these came out about 1976. This is well before the Alpine acquisition in 1984. Maybe the proliferation of so much higher end gear caused problems but they seemed to sell a good bit of it. Worthy gear to restore. Be nice to have sources for these DML units.
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Did you have the original potted (black cube) type DMLs in your C-12, or the Luxman factory replacements (small pin mounted board)? Just wondering if there was an audible difference?
 
My originals in the C-12 were the "black box type". It had a repair early on in its life and one was changed to the open board type. The whole system was in storage for several years and when I brought it back out, I had it serviced and a set of matching Hilberink modules installed. The M-12 always had the open board style DML-01s in it but I also had them changed to the Hilberink versions. To answer your question, the system was put away for almost 30 years while I was raising a family. It now sounds amazing. Factoring in that I can't recall how it sounded exactly new other than "GREAT", and my ears are 30 years older, it is tough to make a fair comparison.
 

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  • C12 DMLs and pots installed.jpg
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I bought a C-12 that was missing two modules and had a boxed one, so that inspired me to make all SMD versions that are assembled by JLCPCB. Crossing my fingers that it works when it gets here.

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