Reference Transports: An overall perspective

Lktanx, so if error correction is only for gross errors, then it seems logical that the transport becomes a very important part of getting the data correct, particularly if it can minimize the random errors that occur in all physical systems. If errors are correlated, then adaptive error correction would be helpful, but how are random errors corrected once they occur?

I agree that once the data is read to RAM, the only meaningful influence on the digital signal, other than digital filtering and D/A conversion, is the precision of the clock. Still, to get the data into RAM you need to read it via a transport, and unless you're claiming that all transports are perfect, I don't see how the transport is not a meaningful link? We could debate the significance of this link, but that's another issue altogether.

Transports are not perfect i.e once in a while they make errors but these errors are detected and corrected by a digital circuit. If the system makes a huge amount of errors, such as when your car CD player skips when you drive thru a bump on the road, then you will hear this. A skipping CD player is an example when too many errors are made which "overloads" the error correcting capability of the circuits.
Note that we a talking about a digital means of data delivery. This is not an analog system like a turntable where subtle issues i.e. spin rate of the turntable can be coupled into the music. The digital system with transport is tranferring 1's and 0's into RAM. It does this with the utmost reliability. Dont forget you are trusting such a system of data transfer when you use your computer on a daily basis.

Germanboxers, I would like to emphasize that you are right; the transport is very important. It is responsible for getting the data correct. However, getting the data correct is very easy and very inexpensive and very trivial. All PCs today rely heavily on CD/DVD transports doing their job well. In a PC, when a transport fails, you throw it in the trash and get a new one.

Lktanx, you do understand that a digital bitstream is just a voltage (analog) approximation of a series of square waves representing the "1" and "0"'s? It's not just mathematics.

I was not referring to massive errors resulting in skips, etc. What I was referring to was the fact that all physical systems exibit some degree of random variation (random error for sampling systems) and these non-correlated errors cannot be "corrected". The question that neither of us can answer conclusively is to what degree does a transport that exhibits less random errors have on the final sound quality?

Ram buffering makes a great deal of sense...on that we agree completely!! Why do you suppose a company like Esoteric has gone through the trouble and expense of developing an incredibly massive and robust transport (VRDS Neo) for exclusive use in players that also SRAM buffer the data? I certainly wouldn't offer this as "proof", but it is interesting that over half the cost in their machines is taken up by the transport mechanism...and all of them read the data to SRAM. It would be interesting to be able to take two of their machines, pull the VRDS Neo out of one, stick a CD-ROM transport in it, and compare the sound side by side.

Anyway, interesting discussion. As an engineer, I'm somewhat baffled at times by what can make apparently meaningful changes in the sound I hear. I'm equally baffled by some of the absolute crazy stuff being peddled by some as well.

Germanboxers,

Yes, the 1's and 0's are represented with voltages. But unlike an analog system where any slight deviation is considered distortion, the digital system is orders of magnitude more impervious to signal variation. Here is an example.

Consider a typical system where 0V represent a "0" and 3V represent a "1". For a "1" to be mistaken as a "0" the 3V will have to drop below 1.5V. In the analog circuit case any variation is bad but for the digital case the signal has to lose half it's value before a mistake is made.

Another way to think about this is that in an analog amplifier, the designers have to make sure that distortion is below say 0.1%. But for a digital system, you can tolerate up to 50% signal change (i.e. 3V dropping to 1.5V) before one error is made. Furthermore if an error is made, the use of error correction fixes this issue.

I can say for certain that the data read from a transport after error correction will be ZERO (unless you're thumping the player with a hammer). If this is not the case you have a defective unit and you should get it replaced. Furthermore, if your defective unit is producing bit errors, you will definately hear it. It will not sound like "the soundstage of the music has narrowed". It will sound someone turned on the juice blender for a brief period.