Are we foolin' ourselves...

[SilverSport]

sadly (or happilly depending on your viewpoint ) bill was thrown under the bus several pages back...

Bill

[anarchist]

Mallett!
The guy who was building HTPC's before it became a marketing term. Welcome back.

Mark,
You obviously read all those papers on CD's and Digital transports at some point in time. Beautiful explanation of jitter is simple terms. It was far more difficult to grasp in the technical papers way back when.

Bill,
You didn't get thrown under the bus. You pointed out the obvious with respect to digital. Not a lot of people want to hear it when they spent thousands for a player and find out some (not all) cheap players can compete with it or surpass it.

Its all about the jitter. Copper surrounded transports aren't going to help. Nor is mounting your cd-player on turntable isolation platforms or placing the transport inside of a tank. Even more importantly, if you claim you are attempting to get the most natural sound possible, you are fooling yourself when you buy a CD-player than implements proprietary algorithms whose purpose is to tailor the sound. Wadia states using certain algorithms they provide will roll off the frequency response substantially.

[SilverSport]

...jus kiddin'...hey, I come here to learn and perhaps a little snappy patter...maybe stir the pot a bit...my own as well as others......thanks!

Bill

[PrestonTom]

Errors that can only be resolved by interpolation are usually due to scratches or nicks on the CD surface. Interpolation is a 2nd to last resort error correction. The last being muting. The normal multi-stage error correction process is quite robust down to 1 bit error in a billion or so bits. And again, it is finite. If the bits are supposed to be 10101, there is nothing "finer" or "better" that can be achieved aside from returning "10101". If you get 10101 from a $20 transport, it is every bit as "perfect" as 10101 in a $20,000 transport. In other words, it would not matter if the error correction were correcting 100 bits per second, or 1 bit per hour. You won't know, and it has nothing to do with the sound, unless you get to the last resort error corrections on a damaged CD which would be muting. Even the interpolation is a pretty good guess at the bits. It looks at the bits preceding, and the bits following the error, and makes a reasonable average between the two.

Yes, there are two degrees of error corrections (big and small).

I frequently borrow CDs from the local library. It is frightening the shape that some of these are in. Some CD players do a better job with their interpolation and buffer schemes. The error correction for the small errors, I agree, is trivial (now days) and is equivalent across players

-Tom

[PrestonTom]

I think the issue that there are no harmonics above 10k fundamental is a red herring.

This limitation is also true for analog as well and is a non-issue since our hearing (as well as the original recording) are both low-pass systems.-TOm

A red herring is something intended to divert attention from the real problem or matter at hand; a misleading clue. I'm suggesting that the limitation may be the fundamental problem.

The assertion that it is a non-issue is based on the incorrect assumption that the analog system has the same upper band limit as digital - in the case of the original recording that is just factually untrue. In the case of our hearing, the extension of the band limitation argument is invalid. The ear and your hearing do not work the way you think. The fastest firing neurons top out at about 1000/s because of depolorization recovery latency. All perceived frequencies above that pitch originate as derived neural signals whose frequencies do not correspond to that of the sound wave. Mid range and high frequency hearing is very complicated and cannot be lumped with audio hardware for comparative analysis.

I really doubt there is much energy (relatively) on a record (especially after it has gone through all the links in the chain) above about 15kHz (typically).

I also doubt that the original equipment used during the recording (tape etc) recorded (relatively) much above 15kHz (or so).

I also doubt that much energy (relative) from the instruments was created above 15kHz (or so).

I also doubt there is much "hearing" ability above 20kHz (usually less for males in an industrialized society - power tools and noise are our downfall).

I also doubt that you understand the depth of my knowledge about auditory perception.

I am not being argumentative, so lets not bicker about my doubts.

-Tom

[Mallette]

Thanks, mdeneen and anarchist! It's good to be home...

Yep, the VPI is new. It exceeds the considerable hype and I have no TT lust left whatsoever.

and, I should have gotten stinkin' rich off the HTPC market. Mine were better then than theirs are now. Still using MBS6. Oh well, wealth isn't everything...

I've never challenged anyone's perception of sound. Whole idea is ridiculous...how can I know what someone else hears? Hence, my signature.

OTOH, certain scientific facts are irrefutable, as your statements attest.

Dave

[DrWho]

Are We Fooling Ourselves...

---

...with high end digital equipment SOUNDWISE???

You should try pulling out your Sony DVD player sometime and compare all three by running their digital output into the same DAC. You're going to get the exact same sound out of all three (unless there is some crazy jitter crap happening with one of the devices).

[DrWho]

The only reactions so far addressing my question about CDs only producing sine waves in the top octave of their frequency response was to be agreed with by one and called a troll a couple of times by another. I raised the question because in a discussion of variability in CD player quality it seems it should be a much more fundamental issue than player mass and construction, isolation, chip sets, advanced algorithyms, etc.

If you are foolin' yourselves, this more fundamental issue might be why...

So how high in frequency does a playback system need to go? You're complaining that a 10kHz square wave and sine wave on a CD is exactly the same thing...but they're supposed to be the same thing! Is 20kHz not high enough for playback? Heck, is 50kHz high enough? Why not set the limit to 1MHz?

Whatever limit you pick, whether it be a digital or analog format, a "square wave" at one octave below the highest frequency is going to be identical to a sine wave.

What you're elluding to may be true from a certain perspective, but you're implying that it has an audible effect that doesn't exist. If a person can't hear above 20kHz, then a 10kHz square wave will sound identical to a 10kHz sine wave. If you claim that you can hear a difference, then you need to pick a higher sampling rate until you can achieve the high frequency limit of your hearing. Of course you'll actually have to hear it for yourself to determine if there's a difference []

[maxg]

A short list of things I do not know - anyone with answers will be most welcome:

Are the lasers on a CD player standard items? Are there better ones and worse ones? Is there some kind of grading system for lasers like there is for processors on a computer - for example?

Isn't reading a red-book CD rather a different process than reading a Data CD? As I understand it reading a data CD allows for multiple passes of the CD to get the best shot at the data whilst Red-book is a single pass system? True or not?

Is vibration control important to a CD or not? Some are strongly arguing not - others are arguing it is. I lean to the latter from the following observation:

I have 2 portable CD players from way back when. One of them will skip if I blink in the vincinity - the other one doesnt skip even when I am running with it strapped to my hip. The latter has (or purports to have) some kind of buffer. I would guess most normal CD players do not. Interestingly the one with the buffer does not sound as good to my ears - using the same headphones as the one without (when I am motionless).

Now - I am happy with the concept that bits are bits - you either read what is there or you don't, but, is time important here? In other words reading a data disk the computer will sit and wait for the data to be presented. The computer has much more processing and facilities than a CD player to deal with the data coming from a CD (or DVD). A CD player has to read and present the information to the DAC in something akin to real time. Where there is need for error correction this must need some finite time to operate. Does Red-book interpolate the data quicker than normal data CD (Yellow book?).

The example of the portable players is extreme for sure, but, it would imply that any vibration the player is subjected to will bring the error correction into play more often. When that happens does the sound suffer - through timing rather than information issues?

[ben.]

Max- your experience could simply be a difference in headphone output performance. Of course that doesn't necessarily render your point any less valid. Everything matters in digital just like it does for mechanical reproduction, I think. Sometimes you get lucky with a cheap & common piece that sounds pleasing, sometimes you don't.

Mike- click on my link regarding life above 20K. It doesn't really address analog/digital issue directly, but you should find it interesting.

I've heard systems that roll off around 12K that really get to the music and I've heard stuff that goes out to 30K that sure didn't do any better. It all matters, but some of it matters a little less sometimes.

[DrWho]

Hey Max,

1) grading systems for lasers would involve wavelength and beamwidth - both are very easy to control and aren't going to affect the sound quality. It will be the difference between being able to read the disc and not being able to. Sound or no sound - nothing inbetween.

2) No - it's the exact same process. There is nothing inherant about redbook audio the prevents the player from making multiple passes. A designer choosing to ignore this option is likely trying to cut covers to meet a lower price point - but it's not fair to consider less than ideal situations when the ideal can be readily achieved...

3) "NO" - at least not in the sense of reading and storing the data on the disc. Some people argue that chassis vibration can affect analog circuits - if you believe that is true, then I would propose using the digital outputs - and then it can't be an issue.

For what it's worth, every CD Player in the world has a buffer of some sort. The anti-shock mechanisms to which you refer are essentially just longer buffers. Shaking the device can make the laser unable to read the CD - in which case the player actually notices that it didn't read the data (commonly referred to as "error correction"). It will then keep retrying to read the CD until it succeeds - which is hopefully before the buffer runs out.

Your reference to the CD-Rom in a computer is a bit misleading because the data retrieval needs to be synched with the CPU and all of the other devices inside the computer. You don't have this constraint in an audio setting. Also, the amount of data being sent back and forth from a data CD inside a computer is many orders of magnitude greater than the data rate needed for audio playback. Ultimately, an audio CD Player needs to be able to read data off the disc faster than it takes to listen to the music. This ensures that the buffer remains full and a constant stream of 1's and 0's is maintained.

As far as error correction - don't get caught up on the term. This is just a fancy way of saying that there are insane algorithms built into the way the data is stored on the CD that ensure that the data read is exactly the same as the data on the CD. These algorithms are nearly perfect. But let's say the "error correction" didn't detect that a bit was incorrectly read off the CD. The audible result is a click or a pop....it's not a small distortion of the original signal. You will KNOW when the data was read incorrectly. I wish I knew the error rates, but they are so extremely rare that they almost never happen....again, think of your computer and how tragic it would be that data changed. You don't randomly see letters changing inside documents you save on CD do you?

Maybe it would help if someone were to list the limitations of digital playback:
Sampling Rate - this limits the high frequency extension of the medium. The hardware available today makes this an arbitrary design consideration. If gains were to be realized by increasing the high frequency extension, then devices would be made to take advantage of it. The fact of the matter is that storing more music on the CD is more important...

Bit Rate - this limits the number of different volume levels. In my opinion, this is one of the more critical aspects that needs to be bumped up higher. Apart from the space issues, I feel this is one of the more important areas that tends to be lacking - especially when you start getting involved with digital signal processing.

Jitter - this has to do with all issues involving an imperfect clock signal. The reason for the quotes around "NO" above for part 3 is that I've heard it argued that vibration can affect jitter.

[SilverSport]

Doc,

I'll give it another listen but that is where I started...my 18 year old Yamaha developed the hiccups and I tried the Sony DVD player as a CD player and didn't like it...now, that being said, it was going through the HT at that time and may have been processed digitally instead of two channel "regular" stereo...couldn't hurt to give it another try...

Bill

[LarryC]

Is vibration control important to a CD or not? Some are strongly arguing not - others are arguing it is.

I'm in the camp that says it can make a difference. My mainstay in this is putting a Townshend air-bladder sink under a Wadia 860 (a one-box CDP player) and clearly hearing reduced sonic grit and grunge. And I don't think many good hifi listeners would have disagreed with me. Could vibration not affect the distance between the laser and a CD's bumps/pits and thus degrade the timing?

[meagain]

Can I ask a question? A couple times, when I put in a CD and sat down.... I thought to myself "this is faster than I remember"..... Like the actual speed of playback has been increased. Am I hallucinating or no? And if not hallucinating.... what part of the system would cause this, or does this anomaly have a 'name'?

[DrWho]

Mike- click on my link regarding life above 20K. It doesn't really address analog/digital issue directly, but you should find it interesting.

Very cool. I have no doubt that information above 20kHz exists....so the next question is how high do our playback systems need to go? I think the answer would entail more than just what our ears can hear too...[Y]

[DrWho]

Can I ask a question? A couple times, when I put in a CD and sat down.... I thought to myself "this is faster than I remember"..... Like the actual speed of playback has been increased. Am I hallucinating or no? And if not hallucinating.... what part of the system would cause this, or does this anomaly have a 'name'?

Slower compared to what? Did the pitch change too?

[wogamax]

I think we are, indeed, fooling ourselves.

Quote: "piano, by the way, is one thing I really hear a lot of differences between CD players in terms of how they reproduce the sound; some sound just O.K. some don't, the Saturn sounds really spot on in this regard"

I couldn't agree more, especially when it comes to a decent onboard DAC. Its heresay from the PortableCDP crowd, but I believe the reason many favor MD is because the hardware formula regularly included a better DAC. I have a DG recording of some piano sonatas that "ice-pick" my ears over CD, but when precisely the same recordings are transferred into the MD they become more lush and less apt to fatigue.

I just read the bulk of this 8 pager in search of the best of the cheap CDP's which include a good DAC. Before buying the Toshiba, I would want to know what music was being played? Acoustic? I suppose Audioreview will fill in the gaps.

[russ69]

I'm quite surprised to find so many stating that all CD players sound the same. I've been in this hobby a long time and I've never heard any two components that sounded exactly the same. Granted some CD players sound VERY similar but they are all not the same. I'm not talking about the handling of the data but more in the differences in circuitry, including the amplifier section. This reminds me of the Julian Hirsch statement "all amps sound the same". That has not been my experience at all.

Thanx, Russ

[pauln]

The only reactions so far addressing my question about CDs only producing sine waves in the top octave of their frequency response was to be agreed with by one and called a troll a couple of times by another. I raised the question because in a discussion of variability in CD player quality it seems it should be a much more fundamental issue than player mass and construction, isolation, chip sets, advanced algorithyms, etc.

If you are foolin' yourselves, this more fundamental issue might be why...

So how high in frequency does a playback system need to go?

This is an excellent question and I don't think the answer has been definitively answered, so best to error on the high side, right?

You're complaining that a 10kHz square wave and sine wave on a CD is exactly the same thing...but they're supposed to be the same thing!

Only for the CD based on it's design spec, not necessarily for other sources that are analog.

Is 20kHz not high enough for playback? Heck, is 50kHz high enough? Why not set the limit to 1MHz?

Guessing from people's experience that 20KHz (CDs) is potentially too low for ultimate audio fidelity replayback, 50KHz (records) may be closer or fine enough?

Whatever limit you pick, whether it be a digital or analog format, a "square wave" at one octave below the highest frequency is going to be identical to a sine wave.

This seems all the more reason why maybe the design spec should be based on maintaining at least two or more octaves between the highest frequency and the highest frequency determined to be important to hearing.

What you're elluding to may be true from a certain perspective, but you're implying that it has an audible effect that doesn't exist.

The "Life Above 20KHz" research indicates the classic "can't hear above 20KHz" is misleading, possibly quite wrong, and that higher is important to some subtle aspects that influence our music perception. There are other research papers that indicate the same thing - that sound up to 30KHz which could not be "heard" never the less changed the way people heard music (they could tell the difference). If this had been known at the time CDs were designed I think the sampling frequency might have been spec'ed up another octave or two. Maybe when and if this happens the CD will become an absolute contender with vinly (and high speed wide tape).

If a person can't hear above 20kHz, then a 10kHz square wave will sound identical to a 10kHz sine wave. If you claim that you can hear a difference, then you need to pick a higher sampling rate until you can achieve the high frequency limit of your hearing. Of course you'll actually have to hear it for yourself to determine if there's a difference []

Exactly! And if ultra 20K sounds do influence our perception of music as the research implies, differentiating sounds in the high range would seem to become important. So many folks are trying to resolve their experience with noticing differences between records and CDs, and possible differences among different CD players... is it so strange to wonder if the presence or absense of sounds we "can't hear" might influence the one's we do hear?

[SilverSport]

I agree with Mark...I think many were saying that CD players or DVD players sound good and the differences are more subtle until you start getting into the higher price brackets...certainly over $1000...

Bill