Today's Transport War: Significant Differences?


I have been reading much these days about computer/hard-drive based transports as being a whole order of magnitude superior to traditional CD transports. In my reading, the camp who believes hard-drive based transports can render major improvements has been most notably represented by Empirical Audio. The camp which suggests that traditional CD transport techonology (or atleast the best of its sort--VRDS-NEO) is still superior has been most notably represented by APL Hi-Fi.

Each of the camps mentioned above are genuine experts who have probably forgotten more about digital than many of us will ever understand. But my reading of each of their websites and comments they have made on various discussion threads (Audiogon, Audio Circle, and their own websites) suggests that they GENUINELY disagree about whether hard-drive based transportation of a digital signal really represents a categorical improvement in digital transport technology. And I am certain others on this site know a lot about this too.

I am NOT trying to set up a forum for a negative argument or an artificial either/or poll here. I want to understand the significant differences in the positions and better understand some of the technical reasons why there is such a significant difference of opinion on this. I am sincerely wondering what the crux of this difference is...the heart of the matter if you will.

I know experts in many fields and disciplines disagree with one another, and, I am not looking for resolution (well not philosophical resolution anyway) of these issues. I just want to better understand the arguments of whether hard-drive based digital transportation is a significant technical improvement over traditional CD transportation.

Respectfully,
pardales
The Noiseball (aka computer) converts audio data many times, uses questionable performance clocking, has switching mode power supply and uses poor interfaces (mostly USB and Wi-Fi packets or combination of both) to transmit audio data to an external DAC. It does not really matter if the USB signal is converted to S/PDIF, I2S or anything else, it still comes from that same USB port! Same applies for Wi-Fi connection where the middle of the audio track may be sent first and then the beginning of it and so on in random packets which are then decoded and reconstructed by a DSP (talk about error correction). There are some nice pro-audio computer cards available allowing much cleaner data transmission and slave mode to the DAC clock, but please realize that all you slave to the DAC is the clock of the computer card DSP, nothing else.

Even a cheap $149 universal player spins the CD, SACD or DVD-A at higher speed allowing for memory buffering using both FIFO and large SDRAM buffers which results in “jitter free” clocks and “bit perfect” data. It is not true that the DAC in a CD/DVD/SACD player has to be PLL-ed (and what’s up with the “evil PLL” thing? Latest PLL techniques are great achieving as low as 30pS jitter!). Good example that comes to mind would be the famous, faulty and long discontinued Philips SACD1000. This player has its main 16.9344MHz non-PLL audio master clock (low noise powered) next to its DACs, the perfect scenario. This non-PLL, low jitter master clock oscillator is also clocking the audio DSPs. Then, PLL is used to generate the 27MHz clock for the video circuit. The SACD1000 spins the CD at much higher speed and uses combination of FIFO and large SDRAM buffers. The “jitter free” and “bit perfect” PCM data/clock transmission in the SACD1000 is carried by our beloved I2S but without any data conversion or long cables and connectors resulting in about 5-6 inches cleanest possible signal path. WOW, isn’t this amazing! It looks like the perfect CD player, the perfect solution, right? Well, I am sure that many around here know for a fact that the stock SACD1000 performance is nothing to write home about, although it was a nice machine for its time. The moral of the story; not everything is as easy and simple as it looks.

IMO and IME, a carefully optimized (key word), vibration/error free “classic” digital front-end using memory buffering and latest error correction engines, with built-in dedicated, specially designed DSPs, shortest signal path, no data conversions to completely irrelevant to audio data transmission formats, ultra low jitter clocking and low noise power supplies simply can not be outperformed by computer based audio, at least not for now. Hopefully in the future the time will come when proper technology will be developed so one is able to load favorite music onto a computer based audio solutions and play it back while achieving the same audio quality as with the classic dedicated stand alone digital front-end is possible today. So let’s stay optimistic.

Regards,
Alex
Aplhifi: if I'm understanding you correctly, you're saying that a vibration/error free front end as you suggest reads different data from a disc than would a lousy CD-ROM drive in a computer? Has this been tested, e.g. is it possible to somehow capture the digital data from a such a transport and compare it to a standard rip from a CD-ROM drive on a computer? Now that would be an interesting experiment! :)

If they are indeed identical, what then is producing the difference in sound? You stated that jitter is not much of an issue anymore, what else could be a factor if we assume that the DAC is identical?

I'd really welcome a discussion on this, it's so hard for me to understand what the problem really is. It should be so simple I think, but demonstrably it isn't since I've too found significant changes between various CD transports connected to the same DAC using the same cable and playing the same disc. How is this possible?

Thanks!
Grant a friend of mine whose products were on display at RMAF was brought down the Nova Memory Player you mentioned above. He heard this player on his system setup at the show after hours. The Nova player was compared heads up to the 10k player they were using in their listening room..he said he wants to purchase the Nova..The copy he made on the Nova and then played back on the other player sounded much better than the original cd played back on either machine. Electro mechanical jitter error correction all of that the Nova guys claim is pretty much gone.Playback from the memory chip internal of the Nova player is even better yet. The Melos crew is back! I recently purchased an Altmann Dac from Germany. Sounds wonderful. Altmann claims with his circuit redo's that the transport makes little or no difference..my listening comparisons so far are making me listen and look harder at transports differences when played thru this little 12volt wonder.Tom
Almost all DAC manufacturers will tell you transport doesnt matter, EAD manfacturer told me the same, because of the digital-flywheel thingy, Transport is very impotant I would say even more than DAC...

I guess If you destroy the original signal (say in a bad computer or a crappy DVD player) and then reconstruct it on the DAC, the result is not the same as if the signal is kept complete (as much as possible) from transport to DAC.

Thanks for that post Alex, it clears up a lot of things for me.

I hope the Nova memory player is indeed much better than a 10k transport, if that is the case we can say good bye to vinil, I hope its not just the next SACD!!!