Quote:
Originally Posted by markl /img/forum/go_quote.gif
My guess is that the new Marantz transport is probably the second best transport on the market right now behind the VRDS NEO, but I'm just speculating.
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Let me play the Devil's advocate...
Transports have 3 basic tasks: (1) read the bits off the media; (2) correct read errors; (3) transfer the data and timing information to the DAC with minimal noise.
I'd say that tasks (1) and (2) are "trivial" for today's high-badwidth computer readers. Perhaps 20 years ago it was important to read the data right on the first try, but current readers really
don't work in real-time. Data is always buffered in memory and a computer checks its integrity. If errors are detected, then they are either corrected by computational means or the computer decides to re-read the data once again. Since the data is buffered and the reader has much more bandwidth than required by the audio stream, re-reading the data can be done without interrupting the stream of output data to the DAC, i.e. it is not causing a "dropout" error. That's not new. Portable CD players use this "electronic anti-shock" trick for over a decade.
The main factor which affects sound quality of modern transports is the third task of transferring the data and timing information noise-free. Here we are dealing with high speed serial data transfers, which are affected by radio frequency interference and are far more sensitive to the quality of the transfer media (cable) and impedance on both ends than low-frequency signals.
This problem is especially severe between seperate transport and DAC units, due to the physical length of the cable and sometimes due to the transfer protocol.
Part of issue (3) is the clock source itself. The high-speed modern readers "just read bits". Data is buffered in memeory and transfered to the DAC based on a local electronic clock, not the spin-rate of the media. The quality of this clock can make a difference, and this might be the one place that a modern transport can be enhanced. The trick is to install a
low noise clock, not necessarily freuency-accurate, like some "super clock mods" offer... Clock quality is affected by the quality of its power supply, so that's another place for potential improvement.
Perhaps we should add item (4) to the list. It is possible that some read hardware in the transport "fixes" the data for you in some manner. For me, this kind of extra processing is just distortion, but it might be part of some cheap reader, aimed at the lowest cost product. Let's hope it's not too common...
Bottom line is that modern basic DVD readers are fine transports from a technical perspective, provided they have a low-noise clock and power supply. The concept of re-working the mechanical part of the transport is not technically viable, although it does have other attractive aspects...
