[Drosera]

Quote:

Originally Posted by digger945 /img/forum/go_quote.gif So if what’s on a CD aren’t zeros and ones, what exactly does represent the analog waveform?

Nice summary! (And much easier to understand than the details of Reed-Solomon error correction.

)

 

[regal]

Digital is an abstraction, in reality there are no ones or zeros flowing from your CD to your DAC. Fact : a digital cable passes a square wave ANALOG signal to the DAC. Ones and Zeros are just an abstraction used for easy math. It gets more complicated when you find there is no such thing as a perfect square wave or that all the pits (ones) in the CD or correct.

 

[tosehee]

On top of that, it's the timing (jitter) issue. passing 1s and 0s is one thing, but at the right timing is another. We talked about buffer, but that's not an easy solution either..

 

[regal]

Quote:

Originally Posted by tosehee /img/forum/go_quote.gif On top of that, it's the timing (jitter) issue. passing 1s and 0s is one thing, but at the right timing is another. We talked about buffer, but that's not an easy solution either..

I know but we are talking timing in the order of magnitude for a beam of light to move less than a meter for the worst transport to be off. Thats why I say the issue is the quality of the square waves and the ability of the transport to read the pits. I think the timing (jitter) issue is overstated, I just can't believe our ears are sensitive enough to pick up on timings as fast as the speed of light to move a meter.

 

[Pars]

You seem to misunderstand jitter. The timing is what is used to clock the DAC chip. If the data is not clocked at precisely the right time, audible errors can occur. The data is still read in a digital form even though it is effectively transferred over an RF carrier (SPDIF), so as long as the '1' and '0' levels are acceptable, the quality of the square wave isn't much of an issue.

A simplistic explanation:
Jitter - Wikipedia, the free encyclopedia

 

[realmassy]

I'm not much into technical things, but here is my experience with transports.
I own a Logitech Duet, which is known not to have a great digital output, but I've always thought the differences were inaudible...until I got today my new Teac WAP 8200. This is similar to the duet, but it has no wifi or lan streaming, and let you play music from an external USB drive.
To cut a long story short, the TEAC sounds different from the Logitech, noticeably different. I have yet to understand what is different, and which one I like more though.
By the way, the TEAC is so easy to use

 

[tosehee]

Unless you are a critical listener who listens to frequency instead of music, you won't tell much of difference between two 'decent' transports. I used 'decent' here because if you are comparing the lousy one to very well known and good transport would definitely reveal more differences.

I have done the ABX testing with fellow local headfiers, and I couldn't tell the difference between Logitech Transport vs. M2tech hiface.

Tarnsport = $1300 or so.
M2tech = $150.

M2tech is one great transport if you are looking for a serious contender.

 

[RickEC]

I have A/B'ed $200-ish CDP transports. Good one has good focus, separations and prat. Bad ones simply sounds dark with missing parts, thin and echoed. I'd be worried for my mind if those are placebo, b'cos i thought i clearly heard them.

I think in some setups, transport makes a difference, while in some others, it doesn't. It really depends on the rest of the setup. If I may say, transport can affect sound quality.

 

[googleborg]

hard disc > any cd transport, ever.

 

[Drosera]

Quote:

Originally Posted by googleborg /img/forum/go_quote.gif hard disc > any cd transport, ever.

I think I would agree with you, if I would have ever actually heard the chain: hard disk -> DAC. Unfortunately, necessarily the chain is almost always like this: hard disk -> crappy noisy computer stuff -> DAC. And then, at least in my experience, even an extremely modest cd- or dvd player can be the better transport.

Asynchronous signal transfer might go a long way to remedy this though. I haven't heard asynchronous USB yet, but I've recently heard some impressive results from a Linn Majik DS (asynchronous network streaming) used as a transport. Still, it'll cost ya.

 

[regal]

Quote:

Originally Posted by Pars /img/forum/go_quote.gif You seem to misunderstand jitter. The timing is what is used to clock the DAC chip. If the data is not clocked at precisely the right time, audible errors can occur. The data is still read in a digital form even though it is effectively transferred over an RF carrier (SPDIF), so as long as the '1' and '0' levels are acceptable, the quality of the square wave isn't much of an issue. A simplistic explanation: Jitter - Wikipedia, the free encyclopedia

I understand Jitter fully. What I am saying is the worst transport ever made has its timing (jitter) off no more than the time it takes a beam of light to travel 1 meter. Think about that, how are our ears that sensitive?

There is more to it than people know. A bad square wave can cause misreads by the reciever chip, thats what I think people hear, missing 1's, or 1's that aren't supposed to be there not jitter. I know I'm a radical on this but I have a strong engineering background and a lot of common sense that is lacking in Stereophile magazine who developed the whole concept of Jitter as being the only difference between transports so their board of directors could upstart a jitter measurement company that was nothing but pseudo-science.

 

[audioengr]

Quote:

Originally Posted by regal /img/forum/go_quote.gif I understand Jitter fully..... I know I'm a radical on this but I have a strong engineering background and a lot of common sense that is lacking in Stereophile magazine who developed the whole concept of Jitter as being the only difference between transports so their board of directors could upstart a jitter measurement company that was nothing but pseudo-science.

First, there have been a lot of jitter studies in the AES so you can read these. Stereophile has no particular role in promoting jitter as a panacea, they are just trying to do their job, and JA does a pretty good job, although not perfect. He just uses the same Audio Precision equipment that the rest of us use.

Second, if you have some relevant experiences, you would know that very small amounts of jitter, in the tens or hundreds of picoseconds can be audible. Just depends on the nature of the jitter, ala spectrum and correlation to the music.

For instance, I have two clocks that I install in my products, both rated at 2psec RMS jitter at 1kHz. You would think that these both sound identical. Well, they dont. You can easily tell the difference in a sufficiently resolving system.

Therein lies the rub. Almost all audiophiles feel that THEIR particular system is very resolving. Well, I have bad news for you. Probably only 1-2% of systems are actually what I would consider resolving. Even lots of reviewer systems from big-name magazines leave a lot to be desired IME. So, when you read a review even from a respected reviewer, take it with a grain of salt. When you read a review from someone on the forums that you dont know, be very suspicious.

Steve N.
Empirical Audio

 

[Prog Rock Man]

Quote:

Originally Posted by regal /img/forum/go_quote.gif I understand Jitter fully. What I am saying is the worst transport ever made has its timing (jitter) off no more than the time it takes a beam of light to travel 1 meter. Think about that, how are our ears that sensitive? There is more to it than people know. A bad square wave can cause misreads by the reciever chip, thats what I think people hear, missing 1's, or 1's that aren't supposed to be there not jitter. I know I'm a radical on this but I have a strong engineering background and a lot of common sense that is lacking in Stereophile magazine who developed the whole concept of Jitter as being the only difference between transports so their board of directors could upstart a jitter measurement company that was nothing but pseudo-science.

That reads as if Stereophile invented jitter and it does not actually exist. Is that really what you mean?

 

[nick_charles]

never mind

 

[tosehee]

Sorry. Couldn't help it..~