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Jud

Semi-Customized DAC Part VI: Ribbons, Mesh, and Teensy, Tiny Screws (Finale for Now)

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"Ken, we're gonna have to take those screws out."

We both started laughing helplessly, in that punch-drunk kind of way you do when you've got to release the stress somehow. "Both" being me and Ken Burton, the master woodworker who not only designed and built the beautiful DAC chassis you'll see more of below, but also had spent an hour or more a couple of nights earlier inserting four tiny screws through tiny washers and 300 micro-inch copper ribbons into thin-walled brass RCA jacks, just to connect the outputs for my DAC. (Ribbons, washers, screws, all from Omega Mikro. Thanks, Ron! - Bauman, one of Omega Mikro's principals.)

Did I say tiny? I think they got these screws and washers from the assembly line where they fasten the flagella on bacteria.

Not only that, but though he'd followed my advice and done the work on a large workbench in case of dropping the screws and washers (the screws had to be pre-inserted in the washers, picked up with tweezers, carefully held in position over the hole in the ribbon and the matching threaded hole in the RCA jack, then tightened - but not too much - with the second-smallest jeweler's screwdriver I could find), no less than three times the screws and washers had popped out of the tweezers, bounced off the work surface and onto the pitted, shadowed, concrete workshop floor below. It was concrete with stone that had mica flecks in it, which just happened to glint exactly like a teensy screw or washer. So we had spent ten or fifteen minutes each time with our hearts in our mouths (no spare screws and washers, we'd have to pay to get more shipped if we couldn't find these) on hands and knees, our faces almost touching the floor, me in a MacGyver moment quickly installing a flashlight app on my iPhone to light up all the nooks and crannies in the rough concrete surface. Miraculously, we'd found both screw and washer all three times, and Ken had finally gotten all four ribbons fastened to the ground and hot connections of the two output jacks. He'd also sleeved each of the two ground ribbons with their insulation, "socks" crocheted - yes, crocheted - of a single strand of #42 gauge, 50 micro-inch insulated, copper wire. Trust me, this is not easy. (Mesh insulation from - yep, you guessed it - Omega Mikro.)

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Ken of Windy Ridge
Woodworks, Woodworker
Extraordinaire and
Master of the Tiny Screws


So I was telling him this had all been a waste - except, as Ken said, desperately searching for something kind, for the fact that it was great practice for next time. And it was all my fault.

I'm right handed, and have a slight hereditary tremor in my right hand. Doh! Couldn't be the left.... This is ordinarily not much of a problem, except for teacups filled to the brim with piping hot tea, or, hmm, just thinking of any random thing here, fine electrical soldering work. In an attack of hubris, I'd tried to de-solder the old Radio Shack wire I'd used for the output connectors in preparation for the ribbons. This was the result:

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I'd taken this shonda (Yiddish for "shame") to Gary Leiby of Electronic Hardware Repair, and he'd patched it to the point where there was once again electrical contact. He'd then soldered the 300 micro-inch ribbons to the board outputs. (Not directly to the outputs, but by using short lengths of very thin - sensing a theme here? - silver-coated copper wire, provided by Ron Bauman of Omega Mikro, soldered to the outputs and then to the ribbons.) It was those ribbons Ken had just spent an hour screwing to the output jacks. But when I took the rig home and hooked it up, though the signal through the mangled output was present, it was lower in level and distorted. I'd need the rig taken apart again, and another board shipped from halfway around the world. Fortunately, my board supplier Albert, who's really responsible for the guts of this DAC, came through like he always does and got me a replacement in just a couple of days.

With the replacement board I returned to Gary with boards, ribbon, mesh, silver wire, and later emailed about a page worth of typed instructions. You see, not only are these ribbons, mesh and wire barrels of fun to work with from a manual dexterity standpoint, the ribbons and mesh are both directional. Also, Ron had told me that although the crocheted mesh was the next best thing to plain air as insulation, it was only the next best thing. If I could get away without it, even better. So I was using the mesh only on one ribbon per pair. Along with the page of directions, I'd cut points onto the ends of the ribbons to show direction, and taped little masking tape arrows onto the mesh. I was glad I wasn't there to see the eye-rolling that I'm sure accompanied Gary reading the instructions and seeing all the little directional arrows on everything. But he was a true professional, calling me only to ask which one of the ribbons connecting the power supply board (these are Omega Mikro's version of heavy duty - thicker, though still quite thin, and a bit wider) should have the mesh on it. I told him it didn't matter, and was once again glad I couldn't see the face that must have accompanied him thinking "I have to be careful of directions with little wire socks, and solder ribbons thinner than aluminum foil, but this doesn't matter?"

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Gary of Electronic Hardware Repair,
Electronics Builder and Repairman
Extraordinaire, Solderer of
Micro-Thin Ribbons

What I'd given Gary was a PITA full of fiddly bits; what I picked up from him looked like the insides of a real electronic component. The one bit of advice he gave me was to point out that the power supply ribbons ran right past a couple of brass board standoffs, and if they came in contact, "That would not be good."

Back to Ken's for The Reattachment of the Tiny Screws. First though, mindful of what Gary had said, I asked Ken to wrap a single thickness of extremely thin packaging tape (a suggestion of Ron Bauman's for insulating places where mesh won't do) around each of the board standoffs in the path of the power supply ribbons. Then, finally, the tiny screws and washers. Ken laid a towel over the workbench so this time the screws and washers wouldn't bounce. (He did drop a screw and washer just once, and I'm happy to report the towel worked!) I drove home with my heart in my mouth, hoping the result this time would be different. I inserted the analog output interconnects, USB and SPDIF cables, turned on the computer and fired up Audirvana Plus, and finally, plugged in the power cord. Nothing snapped, crackled, popped, or went up in smoke - but it hadn't the last time. Audirvana Plus recognized the unit - but it had the last time. I turned on the amp, flipped off the mute switch on the preamp, turned up the volume, started a track playing, and...



:)

It does subjectively sound better to me than it did when it was a bunch of boards lying on a piece of plywood outputting through Radio Shack wires and jacks. Now the electronics are mounted on a 1" thick maple board, which sits on heavy brass feet, which sits on a 2" thick maple block, which sits on cork-and-rubber sandwich feet. The internal power supply connection to the USB/SPDIF input board, the connections for the USB/SPDIF input switch, and the analog output connections are all Omega Mikro ribbons. The four transformer secondaries all have John Swenson's "snubber" circuits wired across them (elegantly soldered by Gary). There is still a bunch of wiring that's, erm, wires - which demonstrates, I suppose, that there's a limit to my craziness.

It's been breaking in for the past week or so (not 24/7, but pretty consistently). Yesterday it had reached the point where everything was very, very clear, and was starting to sound sweeter and more musical: "Hunh, didn't realize that track was so beautifully played." Some music is just breathtaking at this point ("Tigers" and "Stewart's Coat" on the Acoustic Sounds DSD download of Rickie Lee Jones' "Traffic from Paradise" left me with a smile that wouldn't go away). And each track sounds so different from all the others. So it's been worth it.

Here's how it looks:

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Updated 05-18-2014 at 09:25 PM by Jud

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Comments

  1. sandyk's Avatar
    Hi Jud
    Great work, and even nicer to see that it has further improved as electros etc. stabilise.
    I can relate to your comments about tiny screws and tweezers, and it's even more frustrating when there is carpet on the floor, and you need to get down on your hands and knees with a powerful torch to try and find them again. Sometimes you even get lucky!
    I can also relate to the slight tremor in the hand, which for me appears to be partly BP related.
    I cracked up my GP with a comment I made about a further use of tweezers for us old geezers.
    "Sprinkle it with pepper, and when it sneezes,grab it with the tweezers."

    Fell free to have that bit deleted.

    Kind Regards
    Alex
  2. Blake's Avatar
    Looks great Jud! The Omega Mikro ribbon interconnects are so thin and fragile (having owned these myself), that must have been quite the challenge. Eventually, I would be curious if you could provide some subjective comparisons between the sound of this DAC and your prior DAC's.
  3. esimms86's Avatar
    Jud, your DIY DAC is a thing of beauty! You should post your 6 part adventure as an article in CA. Congratulations!

    Esau

    P.S.
    - It's obvious that you've been spending a little time at the Mapleshade store. The woods blend quite nicely.
  4. Superdad's Avatar
    Great work Jud!
    I love the bench you made for my MusiCaps to rest on. Is there anything holding them in place besides the wire tension? They are not particularly microphonic, but I bet that 3/8" thick strips of Mortite clay between each of the caps would be a good thing. It would space them apart evenly, act as damping material, and keep them from going anywhere. If you don't want to see ugly putty strips along the top, then form and slide in some fat triangle strips to in between them at the bottom, wood side. That would be even better since after squishing it all together, the putty will also fix the caps more firmly to the wood bench.

    Enjoy the fruits of your labor!

    Best,
    ALex C.
  5. Jud's Avatar
    Quote Originally Posted by esimms86
    Jud, your DIY DAC is a thing of beauty! You should post your 6 part adventure as an article in CA. Congratulations!

    Esau

    P.S.
    - It's obvious that you've been spending a little time at the Mapleshade store. The woods blend quite nicely.
    Hi Esau, thanks.

    The base that the brass footers are sitting on is a Mapleshade 2" base of "ambrosia" or "wormy" maple. Also, the base of the DAC chassis itself, which the circuit boards and footers are fastened to, is the same material - it started as a 2" Mapleshade block that Ken planed down to 1".

    The top and sides of the DAC are comprised of two different species of wood, both of which we found on an exploratory trip to a rural lumber mill not far from here. What you see on the sides and most of the front (and the back plate as well) is curly maple. The other species - the air holes and the big square piece inset into the top, and the cutouts of the sun, clouds, and mountains glued onto the front - is an African wood called sapele. This particular grain pattern is called "pommele," meaning "apples," due to the appearance of ring patterns from some angles.

    The maple on the chassis and in the 2" Mapleshade base is finished with a light slightly yellowish stain called "Colonial Maple." This was my preference as well as Ken's of the stains and clear finish we tried. It helped bring out the curly maple grain pattern, and will also help keep a consistent look, as clearcoated maple tends to yellow a bit over time anyway.

    The sapele is clearcoated. There was no stain we tried that looked anything like as spectacular as that natural grain pattern with no color added at all.
  6. Jud's Avatar
    Quote Originally Posted by Superdad
    Great work Jud!
    I love the bench you made for my MusiCaps to rest on. Is there anything holding them in place besides the wire tension? They are not particularly microphonic, but I bet that 3/8" thick strips of Mortite clay between each of the caps would be a good thing. It would space them apart evenly, act as damping material, and keep them from going anywhere. If you don't want to see ugly putty strips along the top, then form and slide in some fat triangle strips to in between them at the bottom, wood side. That would be even better since after squishing it all together, the putty will also fix the caps more firmly to the wood bench.

    Enjoy the fruits of your labor!

    Best,
    ALex C.
    Thank you, Alex - your MusiCaps are an important part of the fine sound of the piece. The leads are under little or no tension, so what's holding the caps is simply their own slight weight. I'll ask Ron Bauman about the Mortite - he and Pierre Sprey (the Omega Mikro/Mapleshade folks) have some specific ideas about vibration control.

    The "bench" was a result of thinking about how to run the output ribbons. I knew the caps without any support would just crumple the ribbons onto the circuit board, possibly causing a short circuit, so I asked Ken to make a little bridge for the caps to sit on. It turned out to be less fuss to just run the ribbons under the board, but I decided to keep the bridge in preference to zip-tying the caps, which is how they'd been fastened before.
  7. Jud's Avatar
    Quote Originally Posted by Blake
    Looks great Jud! The Omega Mikro ribbon interconnects are so thin and fragile (having owned these myself), that must have been quite the challenge. Eventually, I would be curious if you could provide some subjective comparisons between the sound of this DAC and your prior DAC's.
    Thanks Blake. Great question, and I've been mulling it over as this new version of the DAC is breaking in. Of course this is all as subjective as it can be, and involves memories of some DACs relatively long gone, but I'm going to give it the old college try.

    When I replaced the Schiit Bifrost with the original version of this DAC, what I immediately noticed was a larger soundstage and a more open, airy sound. When I say larger soundstage, I don't mean that the soundstage was artificially inflated, but that there seemed to be a larger space for the soundstage of each individual piece of music to exist in. Squashed soundstages were squashed; but the recordings I had that were made in cathedrals, for example, gave a better impression of those vast spaces.

    With the Bifrost I'd never changed the Audirvana Plus default oversampling settings, so what I heard was a mix of the Audirvana Plus default filter settings and the Bifrost's filter (since max input for the Bifrost is 192kHz). The new DAC allowed 352.8/384kHz input, and I've always oversampled to those resolutions since getting this DAC (everything other than DXD and DSD), so I've never actually heard this DAC's own interpolation filters. I began experimenting with the A+/iZotope filter settings, settling after not too long on those that sounded best to my ears. Of course I really should have a look at a scope simulation to tell me just what the results really are, and eventually I will do that. And perhaps after these most recent changes I should listen again.

    The results of the filter experimentation were what seemed like the right balance between an open, airy sound and enough "grit" (what I sometimes refer to as the "rosin on the bow" regarding strings), plus better subjective localization of instruments and vocals within the soundstage. I was helped in this by playing a Jordi Savall DSD the day after having seen him in concert from about 20 feet away. I tweaked the filter settings until they best corresponded with my memory of his sound from the previous night.

    The next change was Superdad's caps. Prior to this, the DAC wasn't making any egregious errors of commission that I could hear; but after replacing the original caps with Superdad's, the DAC became much more musical. Instruments sounded more like themselves, vocals sounded more natural - it was the aural equivalent of setting the proper color saturation on an image that had been a little washed out before.

    While the chassis work and rewiring were taking place, I listened through the Geek Out. Nice little portable unit, and great for plane trips, but at home it didn't compare to the new DAC, nor to my recollection of the Bifrost.

    Since getting back the redone DAC:

    - Right from the outset, transients, bass and soundstage were noticeably improved from before the new chassis and wiring. Drums had more immediate impact; bass was very clean, no trace of thudding/drumlike sound, but instead real notes played by real fingers or bows on real strings, though for rock and bass there was no lack of impact. With soundstage, again not artificial inflation but an expansion of the field within which each track's soundstage can be placed.

    - Next, after some break-in, I began to notice tremendous clarity. Rickie Lee Jones is not exactly the queen of enunciation, but on the Traffic from Paradise DSD I could easily hear lyrics I'd had to strain to catch before. Again, this was not an artificial clarity. Grit was there when it should be (various Los Lobos, Tom Petty and Keith Richards/Rolling Stones tracks), but not when it shouldn't.

    - Currently, after further break-in, I'm noticing two addtional things: (1) A degree of realism to vocals I've never experienced in my home audio system. Singers aren't just disembodied voices; when I close my eyes it sounds like people who have not only mouths but chests. (I find myself closing my eyes more often when listening.) I recall hearing this from an audio system just once before, years ago. (One of Mike Moffat's preamps, which he designed before pretty much inventing the modern DAC with Theta, was in that system.) Other instruments sound more real as well, but it was the vocals that struck me the most, particularly when well recorded as they are on various Mark Knopfler/Dire Straits tracks, or Jakob Dylan's first solo album. (2) Each track sounds so different from every other one. They're all wonderful, but all individual. I always kind of shake my head when I read about how a system improvement revealed shortcomings in a recording and made the listener like it less. Yes, the Beatles, Sam Cooke, etc., tracks from the '60s or before are very obviously not recorded like the stuff done with more modern equipment. But they are the very best renditions of those tracks I've ever heard. Just terrific to hear that stuff and be transported back to the same pure joy of my early days listening to those songs in cars, on transistor radios, on 45 rpm records....

    Hope that helps, Blake. :) Questions welcome.
  8. manisandher's Avatar
    Hey Jud, really, really nice. Would love to take a listen to it one day...

    Just a quick question though. I understand the thinking behind using a wooden chassis from a vibration POV. But was there any consideration given to the EMI/RF shielding that something like a copper chassis would have offered?

    Cheers, Mani.
  9. Jud's Avatar
    Quote Originally Posted by manisandher
    Hey Jud, really, really nice. Would love to take a listen to it one day...

    Just a quick question though. I understand the thinking behind using a wooden chassis from a vibration POV. But was there any consideration given to the EMI/RF shielding that something like a copper chassis would have offered?

    Cheers, Mani.
    Hi Mani. The approach re EMI/RF was taken from Omega Mikro/Mapleshade and is non-traditional. Perhaps it has something to do with living in a semi-rural area, but whatever it is, it seems to have worked out. The piece is, to my ears at least, absolutely silent electrically and mechanically. (I realize electrical measurements would be better but haven't taken them - don't have equipment and wouldn't know how.)

    What I take to be the O-M/M approach appears to me to be concerned to a greater degree than usual with chassis and internals. When Pierre Sprey of Mapleshade does mods to old electronics, he replaces their metal chassis with wood. I don't know precisely why, but my guess is that having lots of aluminum around the electronics may shield outside EM fields, but may well reshape and reflect internal EM fields throughout the box. I'd suppose the same could be the case with copper.

    Some design choices were made with the idea of reduced EMI - the R-core transformer and snubber circuits across the secondaries. The internal ribbons are probably not of a length to pick up RF, though other frequencies might be in play. The Mapleshade power cord as well as (I believe) the signal conductor for the USB cable employ twisted pair wiring. When listening to music the laptop runs on battery, has no external connections other than the USB to the DAC, and has all non-essential functions including wi-fi turned off by an optimization script.

    Still, there's no doubt this setup is far from immune to EMI/RF. I think I am probably lucky to live where I do, with low population density and no nearby overhead wires (utilities are buried).

    So EMI/RF was considered, but from a non-traditional point of view that led to a decision not to use a metal chassis.
  10. Jud's Avatar
    Mani, further thoughts:

    I remember just a brief remark in one of Demian Martin's (1audio) comments here at CA re the importance of minimizing vibration in audio components. Now good speaker stands of course I can see, but why electronics? What I thought of, possibly correctly, possibly erroneously, was components or wiring vibrating with reference to other internals and/or the chassis, and thereby setting up internal EM fields interacting with each other and internal components in unpredictable ways. So perhaps the O-M/M approach is a way of both minimizing vibration and minimizing the amount of metal nearby that may generate or unpredictably affect EM fields.
  11. sandyk's Avatar
    Hi Jud
    There is a similar philosophy from Richard Dunn of Nene Valley Audio. (N.V.A. ) who originally used only wood, and wouldn't use metal screws either.
    Regards
    Alex

    Special casework - all NVA cases are made from non-magnetic materials, carefully anodised and glued to eliminate even the minimal magnetic effects of conventional screws.
    NVA Index Frame
  12. barrows's Avatar
    Hey Jud,

    Looks good. I would not worry too much about RF issues with the wood chassis, typically aluminum chassis need to be about 0.5" thick with no holes to really provide a good shield (like CNC machined from block chassis on Ayre R Series gear). In any case, in a DAC, there is a lot of internally generated RF on the USB interface and the DAC chip itself, so shielding may just reflect internal RF around in the case, letting it escape may even provide better sound... I usually prefer damping RF fields if I think there are any sonic problems which I might attribute to RF contamination, as damping materials actually absorb and diffuse the RF energy, rather than just bouncing it around.
    the wood probably results in a very non-resonant chassis, and that probably provides some real sonic benefits. I would do something to fix the output caps in place and damp them from resonances, I affix mine (Clarity MRs) to birch ply and carbon fiber platform in my chassis with silicone, then the platform is fixed to the chassis using double sided foam tape. I bet on your wood shelf affixing them with perhaps a bunch of Blu tack would be really good.
  13. cjf's Avatar
    Very nice work.

    I may have missed it and can't quite tell in the pics but are you using a two prong AC receptacle with no earth connection? The wood chassis would seem like a perfect platform for such a configuration. I guess anything one can do to reduce the possibilities of power grid related noise entering the system is a bonus :)
  14. Jud's Avatar
    Quote Originally Posted by cjf
    Very nice work.

    I may have missed it and can't quite tell in the pics but are you using a two prong AC receptacle with no earth connection? The wood chassis would seem like a perfect platform for such a configuration. I guess anything one can do to reduce the possibilities of power grid related noise entering the system is a bonus :)
    Hi cjf. 3-prong receptacle (Furutech rhodium plated with fuse holder for easy changing - using HiFi Tuning Supreme). To reduce interactions with external power, I've got John Swenson's "snubber" circuits across all the transformer secondaries.
  15. Superdad's Avatar
    Good morning Jud.
    I agree with cjf. You should give a listen to your DAC with the power line ground lifted (easiest to either unscrew/unhook the green wire in the connector at one end of your paower cable, or temporarily use a "cheater" plug).

    30 years ago I began floating/lifting the grounds of all the gear in my system--to great sonic benefit (makes ground loop hum a distant memory as well).. There is nothing worthwhile on the ground lines of your house power that you want creeping into your system. If you are really worried about safety (does it rain in your listening room?), then keep your power amp grounded but float every other component.

    I don't want to go further off topic, but choosing the better sounding side of the AC line and putting all your gear on that side of the line is also a worthwhile exercise.

    Best regards,
    Alex
  16. Jud's Avatar
    I did try the cheater plug thing a few years ago, and did not hear a positive difference. Whether it would change things for the better now, I don't know. Easy enough to try, I've still got the cheater plugs. :)
  17. YashN's Avatar
    It looks to me that you could have use the anti-vibration platform as the very platform to build the DAC with.
  18. Jud's Avatar
    Quote Originally Posted by YashN
    It looks to me that you could have use the anti-vibration platform as the very platform to build the DAC with.
    Hi YashN, sorry to be so late in replying. I actually did something like what you suggest. The base of the DAC itself is another platform like the one you see below the DAC. The only difference is that the platform is 2" thick, while the base of the DAC was planed down to 1" thickness to make it practical to work with.
  19. YashN's Avatar
    No prob, Jud. I forgot to say this look very sweet. Well done!