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My dialouge with a Stereophile editor, real e-mail:


kenratboy

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uh, sunnysal...

No, that's not the LaGrange multiplier. I never could get my head wrapped around that - check out:

http://mathworld.wolfram.com/LagrangeMultiplier.html

and bring an asprin.

The other case is simply:

If we take any infinate series, .9999999... and convert it to a fraction, what do we get?

Well, if X=.99999... then 10X would equal 9.99999..., still an infinate series. Subtracting X from 10X leaves us with 9X=9.0, because subtracting the infinately repeating decimal on the small number from the infinately repeating decimal of the larger number results in exactly zero. Thus, x (or .999....) EXACTLY equals 1.

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Music is art

Audio is engineering

Ray's Music System

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uh, okay...

If an infinate series is *NOT* equal to some value, then there must be a difference between the series and the value.

What is 1 minus the infinate series .999.....?

Don't look at .999.... as a series function which is converging on 1. It is not a function, it is not a series, it is a *NUMBER* that cannot be written down as it has an infinate number of digits.

To go back to the little excercise we posted a few responses back:

How do you convert a repeating decimal to a fraction? You multiply the decimal by the appropriate scale, subtract the smaller from the larger, and you are left with an equation with integer values. For example, what fraction is the repeating decimal:

0.142857142857142857142857142857...

equal to? Well, it repeats after 6 digits, so we multiply it by 10 to the 6th.

1,000,000 X 0.142857142857142857142857142857... equals 142,857.14285714285714285714285714...

So we have X = 0.142857142857142857142857142857... and

1,000,000X = 142,857.142857142857142857142857... so therefore 999,999X = 142,857.0 (subtracting the infinately repeating decimal component of both numbers, since they are identical, results in 0) and

X = 142,857 / 999,999 which reduces to exactly:

X = 1/7

So, we can say that the repeating decimal 0.142857142857142857... is *EXACTLY* equal to 1/7

Note that we are not saying that the repeating decimal is *CONVERGING* on the fraction 1/7th, we are saying it is *EACTLY EQUAL TO* 1/7th.

We now return you to your normally scheduled program.

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Music is art

Audio is engineering

Ray's Music System

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Hmmmm, cluless, I guess it takes "one" to know "one"... -So much for 99 44/100ths pure... you have blackened my Ivory... but what about my redfish? -HornED

PS: But, with the "slight of number" Ray Garrison around, I am not so sure what "one" is...

This message has been edited by HornEd on 07-10-2002 at 11:24 AM

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in new orleans,la.,and surrounding areas we have either cox or charter cable service. digital satellite is FAR better than either of these cableco's offerings. thanks to dishnetwork, i'm able to:

get hd versions of hbo,sho,discovery,and one ppv ch. i also use the built-in digital tuner to receive(hooray!) cbs prime-time via local hd digital re-broadcasts from wwl-dt. my model 7200, which i moved into another room has really cool webtv-based menu options like search,etc. AND a built-in hard drive recorder that records the digital bitstream, so all the movies that come in 5.1 surround are played back w/'identical-to-live' picture and sound quality!! personally i think the only reasons not to have digital satellite are: can't get it., or have so many tv's on at the same time with so many different 'satellite' channels, that equipment costs would be high.

don't be a 'coxsucker' switch to digital satellite!

avman.

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KLIPSCH-So Good It Hz!

This message has been edited by avman on 07-10-2002 at 03:15 PM

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quote:

Originally posted by skonopa:

I'll take a crack at this. I could only guess that if the vibrations are limited in the CD/DVD player, it'll allow the laser to track better, thus not as likely to "miss bits" during playback (realize just how small those pits are on the CD, epsecailly on DVDs - does not take much of a vibration to cause the laser to miss one). If a bit is missed, an error correction algoritm has to try to "guess" at the missing bit and fill it in and in some cases, just let it go. In severe cases, the vibrations can cause the laser to lose its place and the device has to "resync" itself, thus the skipping. This is one reason why CD-ROM drives where more expensive than regular CD players in the early days of CD-ROM drives (I tried to develop a device that would let me use my CD player as a CD-ROM device back when CD-ROM devices where still mucho-$$$), the error correction had to be that much better, whereas, for audio, a skipped bit probably would go unnoticed by the listener. More expensive CD players most likely had better electronics to minimize this problem. Now, play it through some high-end speakers and amplifiers and the listener just may noticed the skipped bits. Enter the roller-blocks allowing the CD player to be isolated and dampened from vibrations, allowing the laser to track better and not as likely to miss any bits in the play back material, thus giving the DAC a more complete bitstream, ultimatly allowing a better quality sound to be produced.


what year was that?

now, i could have a $50 cd-rw, and do perfect backups for data without rollerblocks. maybe we can say that those who got benefit from rollerblock has a very old cd player.

by theory, the rollerblocks are impossible for any digital device. i, like others who don't put their raid cabinets on rollerblocks, will not buy into that.

someone from seagate said, the dimension of a harddrive is like a jumbo jet flying 1 meter high on a field and counting grass. it was back at the time that harddrive has density less of what dvd has now. no rollerblocks, no error visible to a cpu running at ghz. and my ears only catch few khz.

i say no to rollerblocks and calculus.

(rayg, lucky me we don't have mathml. i have serious trauma with calculus i found numerical method a relief.)

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imel

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Do you have a system capable of hearing the difference between a digital copy of a copy and the original? Or different types of discs ie Maxell or Memorex? Or a pristine new LP vs a CD?

Well then, I doubt you will appreciate the rollerblocks, even with a willing suspension of disbelief.

kh

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quote:

Originally posted by mobile homeless:

Do you have a system capable of hearing the difference between a digital copy of a copy and the original? Or different types of discs ie Maxell or Memorex? Or a pristine new LP vs a CD?


can we, at least, agree that a digital copy is identical with the original one?

if we could, we can make progress here. like, maybe the problem isn't at the types of discs, but more at data fetch mechanism failing to correct errors, etc.

could it be that some cd players do worse than computer cd drive in reading bits by showing mechanical behavior?

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imel

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imel,

"can we, at least, agree that a digital copy is identical with the original one?"

Yes, absolutely. The digital information encoded on the CD-R or CD-RW or hard disc or whatever is a bit perfect copy of the digital data on the original CD.

However, the thing that's important to keep in mind is that recreating a music signal using the digital data is different than creating, say, a document by reading a word processor's data file. In the days of floppy discs, I used to diagnose problems with diskette drives in Apple II's, and later things like Osborn I's and cheap IBM clones (Eagle, Hyperion, others.) The computers were unbeliveably tolerant. You could have a drive that varied plus or minus 5% or more from spec (rotational speed, seek time, etc.) and the computer could still read the file. As long as the data were read into memory correctly, the TIMING element was completely irrelevant.

This is not true in digital audio. If the processor is reading, or receiving via external connection, the correct data, it still has to decode and convert this data with a degree of time precision and accuracy which is almost impossible to get your head around. Frecency related differences in the conversion timing of *NANOSECONDS* can have a significantly negative impact on the sound quality (both listening and measuring).

There are external influences that *CAN* (not necessary *DO*) interfere with the accuracy of the clocking of the D/A process. Some hardware is less effective at rejecting these outside influences than other hardward. For example, if the CD-R copy you make of a CD has better defined bit to land boundries than the CD and is truer (more rounder) than the CD (just to use a couple of examples), the extra amount of activity required by the transport to track and read the CD, plus the lower resolution eye pattern resulting from the poorer pit to land transistion on the CD, might very well lead to electrical interference with the circuits doing the D/A process, and result in frequency related jitter components appearing the ANALOG signal. The CD-R might sound *BETTER* than the CD, particularly on equipment that does a less than steller job of isolating the various circuits and components.

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Music is art

Audio is engineering

Ray's Music System

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quote:

Originally posted by Ray Garrison:

This is not true in digital audio. If the processor is reading, or receiving via external connection, the correct data, it still has to decode and convert this data with a degree of time precision and accuracy which is almost impossible to get your head around. Frecency related differences in the conversion timing of *NANOSECONDS* can have a significantly negative impact on the sound quality (both listening and measuring).


that i can i understand. what bothers me now it sounds like cd player maker doesn't do it like it's done in computers.

i know some jogger's discman has memory to act as buffer. maybe what we need is a cd player with megabytes of memory, separate dac clock, etc.

don't you find it strange that computer plays dvd movies without jitter and we're still talking about this?

computers have tons of memory for buffer, but cd players have good dedicated dac. and they say dsp should be cheaper.

i'm curious, since you're a computer guy, which one would you choose? computer or a cd player?

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imel

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CD Player, because I've found the environment in a computer (high levels of RF noise, digital noise, switching noise, etc.) to cause more problems than it solves - then again, I've not heard the newer generations of high end sound cards. Besides, I *HATE* (loathe abhor despise) computers so I tend to minimise my contamination. Biggrin.gif

As to your other point, yes, it would seem that if the folks who had first laid the design from which all subsequent CD players have sprung had simply included a big RAM buffer, with the ability to accurately clock out samples in an environment isolated and shielded from the transport (either external or internal), the CD playback universe we've been living in might have been a lot different. The Genesis Digital Lens was a device that did precisely this, and a lot of folks liked it a *LOT*. Why this approach is limited to portable players that require shock isolation is beyond me. Seems like it would be cheap and easy to implement, given today's cost of RAM.

Ray "I *HATE* computers" Garrison

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Music is art

Audio is engineering

Ray's Music System

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