Sunday, May 17, 2015

Using the Audio-GD DAC 19

Given that I have one tri-amped system and one bi-amped system, all using digital crossovers and EQ, I need 5 DAC's just for those.  These should all be PCM DAC's, according to my current thinking, and I plan to phase out the use of Behringer DCX 2496's and use all Behringer DEQ 2496's, since the DEQ's have digital output and allow use of external DAC's.  I can program the DEQ's to act just like one side of a crossover.  Currently I use two of the DCX's, and they provide 4 out of 5 of the DAC's that I need for my multiamped systems.  The one and only separate DAC currently in use is in the #1 most important location--driving the amplifier which drives the Acoustat 1+1's in my living room system.  Ever since I figured out how to use the DEQ as a crossover last year, I have been using an Onkyo RDV-1 as my DAC (it has a front panel switch which enables DAC-only mode) for the extremely transparent 1+1's.  The RDV-1 was a $4000 DVD-Audio player with PCM 1704 DACs, clock circuitry from Apogee, and built to very high audiophile jewelry standards (for example, all capacitors are a custom version of Nichicon Gold Tune…Onkyo apparently had a special relationship with Nichicon).  It has been compared with some of the best DACs available today, and with the PCM DAC it avoids the sigma delta mist.  When I switched from using the DCX to drive the 1+1's to using the RDV-1, it was a revelation, however it was not a very controlled experiment because the DCX has this positively charming 10V RMS output for 0dB, which wastes at least 9dB of potential dynamic range into a typical system like mine, since the amplifier only requires about 3V for peak output…and I basically never even approach peak output either.  So there were other reasons why switching from the delta sigma DAC's in the DCX 2496 to the RDV-1 made things much better.

Well that leaves 4 DAC slots to fill with new PCM DAC's.  One of the most highly touted online (and an incredible bargain) has been the Audio-GD DAC 19.  That was one of the very first new production 1704 DAC's I read about, and remained highest on my list.  Lite Audio's offerings seem positively pedestrian from a design standpoint compared with the Audio-GD.  Audio-GD pushes the limits of design in what seem like good ways (though I might argue with some).  It brings to mind the design ideas of James Bongiorno, John Curl, Dan D'Agostino, and Nelson Pass.  Minimalist FET circuitry, direct coupled, with no feedback.  (Personally, I'd be happy with the best technology opamp, the TI OPA 211.  It's extremely hard to top that with discrete circuitry.)  Actually the RCA outputs may not be direct coupled, the website only says that the current mode outputs (an interesting idea I may use in the future) are direct coupled.  If there are coupling caps, they are either some nice looking electrolytics, some very small WIMA's, or both.  I don't have the schematic.  I'm happy to have a fully solid state unit since I think tube DAC's are faddish and noisy.  In principle a decent tube DAC could be made, but it seems no commercial company bothers to design optimal tube products.  (And especially not Audio Research in it's Golden Age preamps including up to SP-10.  It's amazing these are so poorly optimized, yet so highly regarded.)  Where tubes are used, it's most often for a kind of sonic nostalgia.  But Lite Audio does make a highly regarded solid state unit that is more expensive than this, the model 83, and I'd consider it, if not for the fact it seems to have soft input switching, and if that loses mode during power outages, I'd scratch it from my list, at least for the bedroom DACs where there is no UPS (certainly don't want any "sealed" but actually H2 leaky batteries in the bedroom).

So when the Audio-G_D DAC 19 came back on the market as the Anniversary Edition, my only question was how many to order.  I decided to play it safe and just order one.  What if it didn't meet my expectations in some way?  What if it had the oily chemical smell as I have found with many products made in China?

Update 7/3/15:  The very slight and not especially unpleasant oily smell that I could smell through the vent holes in the DAC 19 has disappeared after a couple months of continuous usage.  I would not have used it previously in the bedroom.  But even initially it was absolutely nothing like a few previous products from China that required return or discard due to strong chemical smell.  Well only very slightly in that it also, initially, had an oily chemical smell.  Nevertheless I love this DAC and might get another, though I retain some qualms about moving one to the bedroom.  Now returning to my story of smelly products (and, btw, I do think that strangely enough, I have an especially sensitive sense):

And therein is a long story.  I'm not sure when I first noticed this special oily-chemical smell on Chinese products, but it has seemed unique to Chinese-made products, especially heavier metal and/or rubber ones, and not unlike WD-40 but darker and dirtier and with a tinge of something like diesel fuel.  It was certainly apparent with the Weider weight set I bought through Sears Roebuck in 2005.  To keep that smell, which may be less toxic than it smells--but still one wonders, out of my house I first discarded all the packing (which was deeply infused with the smell, and parts of the packing materials looked positively yellow-brown oily), I then hosed everything off, I then washed everything with dish soap and toweled dry--several times and discarding cleaning and drying cloths each time.  When I was done, I had nearly removed all of the smell from everything, but certain rubber pieces still had some smell.  I decided that was good enough for the exercise room.

The next thing I remember, especially, was the Chinese-made KLH receiver I bought at Best Buy about the same time (2005) for $89.  I thought this cheap stereo receiver looked cool, and as I had just gotten used to digital volume controls with the TOTL Yamaha receiver I had just gotten for the kitchen, it might be cool to play with that.  I actually didn't have a specific use in mind.  But not only did this receiver work remarkably poorly (it had very high noise level on line inputs) it had the terrible smell, Especially When it was running, but even when it was not running.  Unwilling to let someone else suffer as a result of this, the final disposition of this receiver was to be boxed, wrapped in double heavy duty trash bags, and discarded to the trash (landfill).  Sad, but that was the only alternative for me.  As a matter of principle I do not unload unsafe or even potentially unsafe products onto other people, even for free.  Also I had not realized how bad the smell was until the return period had expired.

Next to have the bad smell was an IR Thermometer.  It wasn't a Fluke, but it was Fluke's second label brand.  This was a sophisticated $200 electronic product.  It had strong smell.  I was very saddened by this--it got the same treatment as the KLH receiver.  I wrote a bad review that was published by Amazon that has drawn periodic criticism (it appears, some from Chinese).  I don't know if the company fixed the smell problem, but my sample was unarguably smell-defective.

All through this time I carefully check out most little gizmos, and major pieces like Behringer.  By and large nearly everything has been smell-free, and increasingly so.  I've never had a Behringer piece which had oily-chemical smell, even when disassembled.  And needless to say my home is full of little gizmos made in China.  So the problem does not at all affect everything made in China.  And it most certainly has never affected anything sold by Apple (in my experience and expectation).

After I filed that bad review of the IR thermometer, I waited about a year before I bought my next thermometer, and this time I bought the Sears brand so I could return it to the store.  It looked very similar to the one I had previously purchased--but no smell.  I was hopeful my review had turned the tide, that the Chinese now were cleaning up their act.  But how?

Which leads to speculation about where this smell comes from.  Is it a preservative added to rubber and vinyl?  Is it an insecticide?  Is it caused by local air pollution in the factory, it's surroundings, or shipping facilities, even the shipping boats themselves?  I don't know, and it would be very interesting to know.  If perhaps it is caused by air pollution, was it fixed by cleaning up the pollution or instead by forcing workers to wash everything off with alcohol?  In the latter case, are perhaps the smell-free goods the ones which are the greater human catastrophe?

I bring this up not just to describe my thinking and why I purchased only one Audio-GD Dac 19.  Unfortunately the DAC 19 does indeed have a trace of the oily-chemical smell I have associated with certain Chinese products.

It's far less bad than the KLH Receiver, and not as bad as the IR thermometer either.  I can basically (so far) only smell it with my nose within a few inches of the vent holes on the top of the DAC 19.  But it is there, unambiguously, and it hasn't significantly gone away in the two days I've had the DAC 19 powered.  Because of the vent holes on top and bottom, air is constantly circulating through the unit (not something I like in principle) which you can feel, and bringing that oily-chemical smell with it--constantly.  I was thinking the air current might eventually carry the smell away, but it hasn't yet in 3 days.

The packaging material was pristine and has no smell.  The outside of the unit is pristine and has no smell.  There is only something inside which emits a bad smell through the ventilation holes, and somewhat moreso when the unit is running.

I was also worried about the lack of a muting device on this DAC.  How would that work straight into my big power amp driving highly capacitive electrostatic speakers.  Just after ordering, I noticed that fact and immediately had buyer's remorse.  Then I planned to use the DAC as the bedroom monitor speaker DAC.  I feel fairly sure the HCA-1500A amplifier wouldn't hurt the Revel M20 speakers with a few spurious pops.   But on this score, the DAC 19 has worked fine.  The lack of a muting relay has not yet been a problem, in fact it seems to have less issue with changing digital sources than the muting-laden Behringer devices (which can often be driven or switched to make particularly loud pops).

As a result of the smell, I will not be using this DAC in the bedroom, where air ventilation might sometimes be limited to a closed door.  I think it's probably just fine in the living room, where there is constant ventilation.

And in fact I may be using this as the next DAC for my Acoustat 1+1's.  It sounds at least as and perhaps even more transparent than the RDV-1 DAC.  The bass seems deeper and more well controlled also (despite this just being used now down to 80 Hz).  It has a relaxed yet transparent sound.  (Caveat: this is merely a casual observation.  As is my practice: this is not based on any kind of controlled experiment, not even A/B.  On Sunday I simply hooked up the new DAC before powering the system on the first time.  Only the most rigorous tests are of any value, nobody but DBT types bothers to do them, and they basically don't show any differences between DACs that have been substantiated to my knowledge and I wouldn't be the first because this is damned hard work I am not up to.  Anything but the most rigorous test may induce superstitions that are hard to shake.  So I test not-at-all and no listening description is verifiable except as something I remembered feeling.  Did I say my living room system is generally sounding fabulous--though most recently until the Audio-GD I had been obsessing about the harshness on some recordings.  Well on later listening Saturday night it was totally transparent and not harsh, before changing DAC's, playing the Reiner recording of Concerto for Orchestra, except perhaps a tad harsh in a later track where I quit to go to bed.  This is a very challenging piece for all to play, record, and play back.)

Did I also mention it has hard-switched inputs, a knob that stays fixed to one position or another until you turn it by hand?  Thats exactly what I'd like in all my DAC's.  I hate soft-switching inputs which may lose their state during power outages.  It also has another a very nice plus, a front panel polarity switch.  If I were using these DACs for each way in a multi-way system, I could just press all the buttons to reverse polarity--and that would be cool.  Or if I were using it as a headphone DAC.  As things are, it's of relatively little use to me.

It's solidly built, and an incredible value.  Perhaps one of the best DACs there is, at 1/200 the cost of some others.  If they could only get rid of that oily smell.  I'm going to ask.

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