Sunday, June 21, 2020

Archimago on SPDIF

Archimago seems to want it both ways.

1) Jitter, caused by decent quality modern devices, is not audible.  (This is a standard audio objectivist position.  A JAES paper written long ago showed that jitter must be 100-1000 times higher than produced by modern digital devices to be audible.)

2) Nevertheless, you should always use USB, if possible, because it has lower jitter.

I will not hide my feelings here.  I hate USB audio interfaces.  And I am angry that Archimago is hypocritically using his platform to promote FUD (Fear, Uncertainty, and Doubt) of SPDIF type interfaces, while at the same time claiming it's an unimportant issue.  This is weasel hypocrisy.  (Note: in other ways, I truly appreciate Archimago's audio journalism.  He is the best I know.)

I hate USB interfaces because they are a product of the tyrannical Computer world, and will be endlessly subject to planned obsolescence, mandatory "upgrades," computer failures, software failures, complicated hardware, firmware issues, IPP, UPP, Wepp and so on.  It might be possible to make those systems needlessly technically better than the alternative, but at the cost of complexity and brittleness.  When things like this work, fine, but the problem is there may be times when instead of working needlessly but slightly measureably better, they simply don't work at all.  That's what I mean by brittle--rather than bending they break.  That could mean dropouts, or it could mean hours of frustrated fiddling followed by another high dollar trip to the computer store to get another mandated upgrade, including possibly a whole new computer.

SPDIF is a simple and open and unchanging interface which is Good Enough.  Period.  (And this applies to AES as well, but not Toslink--always avoid Toslink if you can--though sometimes it is useful for breaking ground loops.)

SPDIF interfaces also inherently permit an endless chain of devices, with essentially zero loss.  That is mainly why I love them.  I used to dream of having power like this.  You can add any number of DSP processors in line, including devices like Behringer DEQ 2496 which are cheap and powerful, and miniDSP.  Devices like these tend to be open, like the SPDIF interface itself, and let you play with them, rather than being a magic box which does stuff you are just supposed to sit down and like.

Generally, with computer interfaces like USB, everything is supposed to be done by your computer, which generally also means proprietary software, such as Archimago's beloved Accourate, but also things like USB Drivers and USB Firmware, which often require updates on the day of purchase, and months if not years into the future.

There is little or no flexibility in the hardware configuration with USB.  You can't chain devices endlessly (or, plug in devices to record the output of other devices--in fact that is the whole reason why things are sometimes supported on USB and not in free and open interfaces--it's all about the IPP).

With USB, your hardware setup is going to be like this: computer connects to DAC over USB, end of story.

Archimago complains that the Oppo doesn't permit SPDIF or HDMI output when USB sources are used.  Yes, that's kind of the nature of the USB beast, generally speaking, and getting around it requires fancy footwork rarely seen (and I wonder if IPP would get in the way also).  Archimago hints at what Oppo should have done for USB, to permit SPDIF and HDMI downstream and it doesn't sound trivial.

Possibly Archimago's endless pushing of USB interfaces is they are the ones best suited, at this time, for multichannel audio.  There are already existing standards for high resolution multichannel audio over USB.  (Which will change every few years, of course, which is back to one of the big reasons I hate USB.)  And multichannel audio is one of his big things.  I think objectivist audiophiles tend to oversell multichannel audio.  I think it's barely worth the effort for music.  I'm working on it myself as a fun extra thing, but only that.  Not worth the bother, at this time, for most people, IMO.)

Just take a look at Archimago's peerless and wonderful review of the Oppo BDP 205, where he shows the performance of the UDP 205 as a DAC.  Here you can compare the performance of his beloved USB and the SPDIF/Coax interface.  Is there a difference?  Yes but smaller than with practically anything else.  We're talking a handful of tiny ticks at the reaching from the -155dB noise floor to about -145dB.

24/96 is also Good Enough.  What is the theoretical S/N ratio of 24 bits?  144dB.

Is there an asynchronous type interface which I like for audio?  Yes.  Ethernet and wifi, which are also basically open interfaces.  Ethernet never locks you down to a specific computer like USB does.  It isn't specifically part of the Personal Computer world.

I don't like using computers directly as audio sources either.  I like dedicated players, streamers that connect via Ethernet, and things like that, not things that are going to tell you that another update is going to be needed today.

I suppose, if you are going to be using a computer as your audio source, not mediated by a player connected through ethernet, etc, then USB is fine, and yes it may be the way to go.  So use USB if it's applicable like that.  I can't say you should never use USB.  I use USB audio solely for doing audio measurements because computer based measurement systems are almost unavoidable.  And every time, it's a pain, because the computer needs an upgrade or whatever.  Unlike traditional audio gear, which is near timeless and universal, computers are cranky and immediately obsolete after purchase.

But you should not be badgered into buying a new DAC simply to attach via USB because "it's better."  Or abandoning non-Personal Computer playback systems to reach that goal.  The alleged benefit in lower jitter isn't worth it.  In fact, it isn't worth anything at all.

While Archimago dabbles in the like of DSD and 24/386, which may require USB (or, gasp, HDMI), he also believes that nobody needs a sampling rate higher than 50kHz.  Well then SPDIF is just fine, again.

It should be understood, anyway, that I truly appreciate the very fine work Archimago continues to do.  In this incredible blind test, involving a large number of listeners, he shows, once again, that the differences between DACs, even much larger and more obvious differences than the ones caused by SPDIF jitter, are so small that they appear to be inaudible in fair tests.  But this, once again, shows the tiny differences caused by the "jittery" SPDIF interface are inconsequential.




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