Will digital CD audio differ from player to player? (1 Viewer)

[Justin Lane]

The burden of proof should be on the DBT proponents. If I am required to offer up definitive peer-reviewed evidence of low jitter audibility, then why not a burden on people to produce papers where it is found that jitter has no audibility to these levels?

Wait one second here, I totally disagree with this statement. The burden of proof should be on the group that says "something is there, but we do not have the technology to measure it at this time". It is up to that group to establish proof or improve upon the technology to prove their claims. A claim made without any data that could be constituted as proof is baseless. Sheesh, I thought we lived at a point in time where people realized the benefits and importance of proper scientific procedure.

J

 

[Ian Montgomerie]

The low-power signal from the read head, as influenced by the precise location of pits on the disc, is not a noticable hit on the transport power supply considering that this power supply is driving the servo mechanism, the CPUs and memory, and other much bigger sources.

I respectfully disagree as many engineers have noted power supply effects which induce jitter. Jon Risch discusses this on the prior link.

You obviously don't understand what I just said. The transport power supply supplies most of the current to the servomotors, powering the pickup laser, running the onboard CPU(s), running the onboard memory, etc. It also supplies a (relatively speaking) very small amount of power to convert the reflections from the laser into an analog electrical signal. The only thing in the entire system vulnerable to "pit jitter" is the impact on the power supply of slight variations in this optical->electric conversion. But that conversion is insignificant compared to all the other stuff affecting the power supply. Like I said, comparing this to _the other things affecting the power supply_ is like worrying about a buzzing mosquito in a windy field where someone is using a chainsaw (the wind is other general interference on the power supply from the electronic circuitry, other devices in the room, etc, and the chainsaw is the servomotor). There is absolutely no way variations in the current used to generate the analog signal from the read head would introduce jitter/noise that would be at all measurable above the noise floor of the system.

 

[Ian Montgomerie]

You need to read the DCS pdf more closely, the bulk of the paper explains why connectors of the optical exhibit jitter.

I obviously read it more closely than you did. The bulk of the paper explains what jitter is in general, gives a numerical example of how a 20m twisted pair cable (an ELECTRICAL cable, with the signal measured by a scope) leads to jitter, and then describes how a standard receiver PLL will eliminate the vast majority of that jitter.

Then at the end, there is an unsubstantiated, numbers-free argument that optical cables may have worse jitter properties for some not-well-described applications.

 

[Lewis Besze]

The burden of proof should be on the DBT proponents. If I am required to offer up definitive peer-reviewed evidence of low jitter audibility, then why not a burden on people to produce papers where it is found that jitter has no audibility to these levels?

Ok so why don't you subject yourself to such test Lee?
It would serve both parties well.
Remember DBT's by nature won't "explain" differences in any 2 components,but rather point out, how poor the human auditory sensors are,when you fail to "reckognise" the different rate of jitters.
We know jitter exists,we don't know how it would manifest itself, in the audiable analog domain!
More focused soundstage,better micro dynamics,more air,more faithful vocals?
PLEASE!!!!!!!!!
Sounds like buzz words from the latest motivational guru's book!
I'll pass,[this "book"]but you shouldn't Lee,and invite John K.to do the switching,to keep this balanced!

 

[Lee Scoggins]

It is up to that group to establish proof or improve upon the technology to prove their claims.

Why?

Why should we have to prove audio events in scientific terms?

 

[LanceJ]

Regarding the power supply/jitter issue: is this possibly why so many upscale CD players are now equipped with such huge power supplies? Seems wasteful.

No wonder hi-end audio is becoming so ridiculously (stupidly?) expensive.

LJ

 

[Lee Scoggins]

Regarding the power supply/jitter issue: is this possibly why so many upscale CD players are now equipped with such huge power supplies? Seems wasteful.

Yes, these beefier supplies help to mitigate the problem. It's not wasteful, it's functional.

 

[KeithH]

:yawn:

 

[Ian Montgomerie]

Why should we have to prove audio events in scientific terms?

I can see I've been wasting my time in this discussion. Later all.

 

[LanceJ]

:yawn:

Keith: yea, I can relate (believe it or not).

But I also see many people confused by all that ridiculously overbuilt, under-researched equipment out there that SUPPOSEDLY sounds so much better than "mid-fi" components built with facts, solid scientific & engineering theory (and testing) and some by-the-ear final tuning ("voicing"). That last part allows me to buy speakers I personally like, like Boston Acoustics, and not get stuck with dry sounding speakers from.....well, I'll just say certain "other" manufacturers.

There is just too much audio voodoo and audio pseudo-science out there for me to sit idly by and not say anything!

I see audio splitting into two different camps lately: one desires a truly accurate reproduction of the original sonic event. The other seems to just want equipment that manufactures what they think sounds sonically correct.

But against the latter kind of belief system, nobody could win an argument.

So like Ian, I'm outta here.

LJ

 

[KeithH]

Ian, later.

 

[John Royster]

And to Lance's point...

Lance - have you ever heard hi-fi stereo? I'm talking about reproduction of music so real that it ceases to sound like a stereo anymore and more like a performance?

I also have been fond of boston accoustics for 20 years. But I bet you couldn't tell the difference between them and other manufacturers in a DBT.

 

[Lee Scoggins]

I can see I've been wasting my time in this discussion. Later all.

Ian,

I am sorry you feel this way. I understand the faith you must have as an engineer in the scientific method.

Fortunately I think in many ways, science does not explain the beauty or life around us. This is particularly true with audio. While certain key metrics may describe part of the sound, they do not explain all.

The best way is to listen to what gets recorded in a controlled environment like a studio and compare the more natural sonics found to what is observed by measurement and continually notice correlations. A balanced combination of science and listening.

Take jitter, for instance, as a long-time audiophile I was around in the 80s when engineers and physics types were claiming all transports should sound the same. Then some more open-minded engineers started discovering that jitter made a difference. Stereophile bought a jitter analyzer and started noticing that poor sounding transport indeed had high levels of the time distortion and could be picked out blindly. Things changed dramatically and chips and implementation started to improve the levels (lower) of jitter. CD sound evolved substantially. It is now at the point where my team plugs in an external master clock to get jitter down gto 20 picoseconds and we hear it!

So the questions are:

What else is left to discover? What's the next jitter?

What phenomena can science not explain at the current time?

It is a question of not whether one believes in science (I think we all do) but which of us understand its very real limitations in capturing audio events.

Have a great weekend!

 

[KeithH]

I wish I had a way to measure jitter. As I said earlier in this thread, I once compared a Sony CDP-CA80ES carousel changer and a Pioneer CLD-D406 LD/CD player as transports (both with Radio Shack optical digital cables). The difference was night and day, ans the 'D406 was simply lousy. I don't know if it was a result of high jitter or not, but I would have liked to have been able to measure it.

 

[Lee Scoggins]

I don't know if it was a result of high jitter or not, but I would have liked to have been able to measure it.

You need, unfortunately, a rather expensive jitter analyzer but Stereophile and other magazines have published some numbers on common transports. Some high end players have published specs wrt jitter.

 

[KeithH]

Lee, I realize all that. I was essentially thinking out loud. Everything in electronics comes down in price eventually. When is someone going to come out with a jitter analyzer for, say, $50? It would have to be portable, of course, so we could measure jitter when demoing players at stores.

 

[Lee Scoggins]

When is someone going to come with a jitter analyzer for, say, $50? It would have to be portable, of course, so we could measure jitter when demoing players at stores.

Well it may take more than $50 as most jitter devices analyze now across the spectrum which is not easy to do.

It may be possible to require chip mfrs (maybe they do) to share information on ADC and DAC performance. Alot of digital cable manufacturers do.

I did an interesting jitter test over the weekend. My friend Jeremy Kipnis created an audio test for Chesky Test Sampler Volume 2 that compares high jitter and an audiophile low jitter cable. You can really hear the difference even in 44.1. The low jitter cable has a much more focused sound on the transients. The demo material was a fast-paced drum solo...

 

[KeithH]

Lee, I wasn't being serious. I can always dream, can't I?

That jitter test sounds interesting. I'd like to hear that myself.

 

[MarcVH]

So, engineers discovered that jitter made a difference. How did they discover this? Did it involve applying the scientific method, or if not, what took its place? Is a "jitter analyzer" a scientific instrument, or is it something else, like a religious ritual or a magic 8-ball?

 

[John Royster]

:rolleyes