Hard Drive versus Optical Drive

Why is a hard drive thought to be a better source for digital than an optical drive in a standard transporter? And, if true, why is something like an Olive HD music server, not the obvious choice for a "transport" to DAC system?
Other than the convenience of storing, archiving, and selecting music through a computer interface, is there no reliable information to suggest why a computer hard drive would be a better source, in terms of sound quality, than dedicated audio transport of high quality with excellent power supplies? Convenience is a perfectly good reason for going computer-based (after the invonvenience of setting it up right), but is it really as good as what we have now - Redbook CDs (or SACD, DVD) and a SOTA transport?
My feeling is that it is an example of a phenomenon that happens frequently in high end audio. An advantage that a certain design approach or technology may have, which at best is significant only marginally and occasionally, is viewed without proper quantitative perspective, and as a result is over-hyped.

Nearly all cd transports and cd players read each bit, byte, and word exactly once as the disk is being played. If an error occurs in that reading, error correcting processes that are provided in the format usually allow on-the-fly correction of the error, with bit perfect accuracy. But occasionally an uncorrectable error will be encountered, particularly if the disk is scratched or otherwise not in good condition, in which case either interpolation (essentially guesswork by the machine as to what the sample value is likely to be) or muting will occur.

Data from a hard drive, on the other hand, can be read multiple times, if necessary, by the associated computer-based hardware, so that bit-perfect playback is more likely. The PS Audio Perfect Wave Transport emulates that kind of process, and is able to do that by virtue of the fact that it contains a very large buffer memory, into which data can be written at much faster than real-time rates.

That's the theory. I don't have meaningful statistics readily at hand about how often uncorrectable errors typically occur when doing single-pass reads of cd's, but for disks in good condition my impression is that it is either zero or a small handful of samples AT MOST (44,100 samples occurring per second for redbook cd's). So under typical circumstances that theoretical advantage of hard drive playback will be insignificant.

As always, of course, specific practical implementations of either approach may vary significantly in quality and performance.


-- Al
Ah. Now I understand the theoretical advantage in terms of getting bit perfect reads, but it does sound like a theory that has little practical effect and is likely to be overridden by other factors, such as power supply and regulation in a quality "transport" - it does not seem like a reason to make the move to computer since I suspect that it brings on problems of its own especially with no audio specific connector standards, etc. I think as long as I own silver discs (2,000+) I'll continue to use my Meitner player. Now, if the world moves to readily available hi-rez downloads of the vast musical archive, well that would change the equation; but that might be a way off. The one type of "music server" product that does seem interesting is something like the Olive HD (I'm sure there are others)that can store the music on a hard drive with a nice user interface for finding music and make selections through your collection, along with a optical disc that can paly straight from disc. It sounds good, as long as it can perform as well as the best transport/dac/Cd-players available.
I've been struggling with this one for a while. I don't own a lot of CDs, less than a few hundred overall and no more than 50 or so that I access for playback at any given time. I still tend to buy CDs here and there, but mostly vinyl. So while I have what I consider to be a very nice transport/DAC combo, I've often wondered whether I should go to a computer or hard drive based system. I am interested in online music down loads so there is a benefit to not having to burn CDs, but the whole aspect of which method is better, HD or computer, firewire, ethernet, USB, or wireless, totally confounds me.

I've been very interested in the Transporter and like the idea of the Squeeze Touch (or other options that let me use my existing DAC). However, if that isn't enough you have the discussion Tbg started on SSD vs. optical drives. Go over to the Computer Audio asylum on AA and there is enough information to rattle your brain for days.

Granted, I think the computer and HD systems can offer better reads, possibly better sound, but more convenience? It certainly hasn't been very convenient for me to figure this all out.
That's the thing Tony, we are not exactly computer illiterate or phobic and yet we (I agree) feel confounded; it seems like audiophiles are going to have difficulty with this until they make it really much simpler, and with some standards for best performance. I think the Olive HD as a platform looks great, just don't know how it would sound compared to my EMM CDSA-SE (yup, I sold the AA Transport and DAC).
Paul, I was wondering about your transport/DAC combo.

There is another thread here where Kijanki talks about using Airport Express with optical cable connected to the Benchmark DAC1. Now to me that is pretty simple. Of course my DAC only has SPDIF input. I may have to give the Benchmark a whirl.

Luckily CES starts Thrursday and since I live 8 miles West of the Venetian and Flamingo (THE SHOW) I'll be able to get some more of my questions answered this week. What I have determined so far is that USB is not the answer and unfortunately firewire is being phased out by Mac (otherwise the Weiss Minerva would be very attractive to me). There are some good things said about wireless and ethernet, but then like all the other options, sorting out the hardware is another matter altogether. The Olive HD is nice, so is the Zero One. Unfortunately with the Zero One you can't stream, the Olive can. For $2k it may be a viable option.

Think I'll go spin a disc now.
Clio -- My understanding is that firewire is not being phased out by Mac. What has happened is that firewire 400 has been superseded on Mac products by firewire 800, which uses a different connector. However, adapter cables are readily available which will interface a fw800 connector to a fw400 connector, and backwards compatibility that is designed into fw800 will allow it to work perfectly well with fw400 equipment (at fw400 speed) through that adapter cable.

Also, I have seen no indication of fw400 being abandoned on non-Mac pc's, and I would expect it to be around for a long time considering the plethora of digital video camcorders and other products with fw400 interfaces that are out there.

-- Al
Al, thanks for clarifying that. I can't recall exactly, but I thought I read where the new MacBooks would not have firewire ports, leading me to my conclusion.