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With surface mount
chips
it became practical to have the boards OEM'd to our specification from
a manufacturer in China and then complete them here. When they arrive,
we inspect them to be sure the parts are per our specification and no
substitutions were made. Then we resolder the entire board by
hand using a solder with high penitration and containing silver. Then
we do a 48 hour test to insure
everything is working to spec. At this point we install the analog
stages with matched components and continue to test. The next step is to
install the
finished board into the chassis using a special process that eliminates
90% of the vibration or resonance of the board itself. Yes, tube dampers make tubes sound better
and the same principles are true for solid state components.
This
technique
also
eliminates
micro-cracks
caused
from excessive G-forces
that occur during rough handling during transport and ensures that
fatigue
cracks from vibration in the
solder joints never develop over time . To enhance the
reliability even further, a high temp oil and gas resistant coating is
applied
to the finished board. This does two things; locks the part bodies to
the board eliminating individual resonances of those parts and
insulates the leads and all solder making the board nearly waterproof.
The pin spacing on surface mount chips is not much wider than a human
hair, so it only takes a piece of metal dust to land between them to
create a short and render your DAC useless. This coating virtually
eliminates this possibility and makes the DAC immune to sound changing
humidity as well. We make the chassis to
match our ZBOX tube output stage so that the two products could be used
hand in hand. It consists of heavy gauge steel with a thick baked
on powder coat finish that is almost impossible to scratch. The
finish is on the inside as well, including the holes, ensuring that
rust will never plague the appearance. Like all Decware products, the
jacks are top grade Gold/Teflon RCA outputs, and the best most
expensive IEC connector made. Switches are high grade toggles
with silver contacts. China can make a decent circuit
board. The parts on the board, ie., caps, resistors, chips, etc.,
are not made in China. However, when it comes to RCA jacks, IEC
connectors, chassis, and just about everything else... Chinese parts
are complete junk.
NOTE TO D.I.Y. guys: The company we use in
China to produce the boards for our DAC is also producing their own
version of it and selling it on eBay. Admittedly this gave me
great pause for obvious reasons... but it IS a great opportunity for
someone wanting to build their own DAC and install it into their own
chassis. Of course the DAC on eBay is not going to sound anything
like our ZDAC-1, but if a guy wanted to buy one and figure out which
board version he has, where the errors are on the schematics, what mods
to do and so on, you should be able to get a pretty decent sounding DAC
out of the deal for a reasonable cost. Here is a 130 page
thread on the eBay dac: http://www.diyaudio.com/forums/digital-line-level/137976-experience-diy-dac.html Decware will not be
offering the ZDAC-1 in kit form and will not offer any support or
advise to those who purchase the eBay dac.
FINAL COMMENTS: As everyone knows, tube
amplifiers are our main forte and everything we build here is by hand
one piece at a time. I was very reluctant to use a Chinese
contractor to manufacture our boards for this project. I've got
many dac boards spanning back over the past 5 years that we built and
stuffed here that could be used for this project... and had I used them
it would have avoided the need to write this paper entirely. To
build this DAC board in limited quantities here would have cost me an
additional $300.00 per board. That would have translated into a
much higher
price ZDAC-1 or a watered down version of it that doesn't make the
grade sonically. My goal was to create the very best sound
quality possible for under a grand and to make sure that it was well
above the overwhelming number of sub one thousand dollar dacs already
being sold by other manufacturers. The way I see it,
despite having the board stuffed in China, the parts on it are not
Chinese. We do all the QC and final assembly and soldering by hand
making the ZDAC-1
a FAR CRY from the typical practice of purchasing a finished product
designed and built in China and then re-branding it as so many
manufacturers do.
Steve Deckert
Decware is a trademark of High Fidelity
Engineering Co.
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