Howie related very nicely a research project, magnetizing and green pens had no effect on the recovery of data from a CD, I thought there is an end to end purpose for the system.
Bit Error Rate translate to jitter, I don't see a lot of sense in this construct, again the "bits" here are the desired end result. This is becoming a little pata-physical.
TOSLINK laser's, certainly not in 1983, Toshiba invented it the current catalog mentions only LED's. I have to admit it is disconcerting how easy it is to buy VERY non-eyesafe lasers.
Just checked Digikey even the 500Mb/s ones us a 650nm LED, what's the application?
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For you, perhaps. For me, likewise. For others, the "story" is more important than actual results.
John, you had a problem with Howard's presentation? It was nice to see something that clear and detailed, and Howard's credentials are pretty good i.e. he was doing his job as an engineer.
Looking at what The Audio Critic says, some of it is right, that reviewers have hidden incentives and such.
I think everyone would appreciate more reviews like this, is sort of what I was referring to, i.e. blind evaluation without incentive
The Great Capacitor Shoot-Out
"While these were not blind tests in the strictest sense, where the set-up was hidden behind a screen, JL played the role of techie, switching the subjects in and out, and the panel was generally unaware of which cap they were listening to at any given time. They were also unaware of the price point until the final pecking order was announced. While the order of play was seeded, much like a tennis tournament, in which those with the lowest expectations were installed first followed by those for which theexpectations were the highest, the end result often differed in the final sequence. With few exceptions, there tended to be general unanimity among the panel members about the attributes and deficiencies of each subject. JL kept notes about the individual comments and these are summarized below"
I think everyone would appreciate more reviews like this, is sort of what I was referring to, i.e. blind evaluation without incentive
The Great Capacitor Shoot-Out
"While these were not blind tests in the strictest sense, where the set-up was hidden behind a screen, JL played the role of techie, switching the subjects in and out, and the panel was generally unaware of which cap they were listening to at any given time. They were also unaware of the price point until the final pecking order was announced. While the order of play was seeded, much like a tennis tournament, in which those with the lowest expectations were installed first followed by those for which theexpectations were the highest, the end result often differed in the final sequence. With few exceptions, there tended to be general unanimity among the panel members about the attributes and deficiencies of each subject. JL kept notes about the individual comments and these are summarized below"
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Scott, Howard's presentation is excellent and very informative. My background is photonic packaging. I have been at for for some 33 years. The electronics parts is what I know least and that is why I am here. But I do know the optics part. And yes, BER in the optical Domain is can be a component in jitter, but this is not mutual. All I am asking is did he look at the signal in the optical domain, not at the flag pin of an IC. All you have to do is tap into the PD'd pins and take this signal direct.
But the flag pin tells you if you have an error. No pulse, no error -> no problem.
You mean an electrical signal.
You mean an electrical signal.
E32 and sonic change
You excerpted my statement and left out the most important part, so I'll repost it: I said: "If on that single player, between two bit-identical discs there are no E32s there can be no difference in sound."
Analog contributions inside a player such as the ever-present tracking servo hash bleeding into the audio supply would be there in either case, since we are talking about the one player. Therefore, any differences between two bit-for-bit identical discs in that one player will indeed be due to E32s.
Change one variable at a time, please!
Cheers!
Howie
Howard Hoyt
CE - WXYC-FM 89.3
UNC Chapel Hill, NC
www.wxyc.org
You excerpted my statement and left out the most important part, so I'll repost it: I said: "If on that single player, between two bit-identical discs there are no E32s there can be no difference in sound."
Analog contributions inside a player such as the ever-present tracking servo hash bleeding into the audio supply would be there in either case, since we are talking about the one player. Therefore, any differences between two bit-for-bit identical discs in that one player will indeed be due to E32s.
Change one variable at a time, please!
Cheers!
Howie
Howard Hoyt
CE - WXYC-FM 89.3
UNC Chapel Hill, NC
www.wxyc.org
sidebands at the right frequency to be caused by spinning disk/servo tracking current coupling to analog out can be seen even with a ESI Juli@ looking at a cheap Oppo universal player output with a test disk
at inaudible level when psychoacoustic masking is considered
but no bit were harmed
at inaudible level when psychoacoustic masking is considered
but no bit were harmed
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The tests weren't blind, much less double blind. Done double blind, the correct way to evaluate by ear only (no peeking or preconceptions), the results are quite different.
E32s redux
Snap. Even a 1x audio CD player actually keeps buffering pretty far ahead of real-time in order to keep it's buffers full. DJ CD players that seem to start instantly actually read ahead, store, and then play from the storage initially when the start command is received. Of course there could be poorly designed players out there, with an almost infinite variety of flaws. I've seen more of them than most everyone on this list, so you will NEVER hear me say ALL CDs play perfectly all the time on all players. If they did I wouldn't have had a job.
All I am saying is: as long as the errors can be corrected...what DF96 said...if the number 2 goes in and the number 2 comes out...where is the problem? Maybe the issue is a lack of knowledge as to the flow of data in a CD player? There are multiple buffers, run by different clocks. The demodulated EFM buffer controller controls the spindle servo to keep full, and in turn feeds corrected data to the descrambler/error concealment circuit. The output data to either the D>A or digital output is clocked from a buffer by it's own fixed frequency clock, so the jitter and/or errors on the disc do not ripple through to the digital output. Bad or missing data may, but not the raw CD jitter or error.
All of this circuitry is in line with the data all the time, and the output bitrate is not related in any way to the EFM data rate off the disc. A good reference for this is Ken Pohlmann's 'The Compact Disc Handbook'.
Cheers!
Howie
Howard Hoyt
CE - WXYC-FM 89.3
UNC Chapel Hill, NC
www.wxyc.org
Snap. Even a 1x audio CD player actually keeps buffering pretty far ahead of real-time in order to keep it's buffers full. DJ CD players that seem to start instantly actually read ahead, store, and then play from the storage initially when the start command is received. Of course there could be poorly designed players out there, with an almost infinite variety of flaws. I've seen more of them than most everyone on this list, so you will NEVER hear me say ALL CDs play perfectly all the time on all players. If they did I wouldn't have had a job.
All I am saying is: as long as the errors can be corrected...what DF96 said...if the number 2 goes in and the number 2 comes out...where is the problem? Maybe the issue is a lack of knowledge as to the flow of data in a CD player? There are multiple buffers, run by different clocks. The demodulated EFM buffer controller controls the spindle servo to keep full, and in turn feeds corrected data to the descrambler/error concealment circuit. The output data to either the D>A or digital output is clocked from a buffer by it's own fixed frequency clock, so the jitter and/or errors on the disc do not ripple through to the digital output. Bad or missing data may, but not the raw CD jitter or error.
All of this circuitry is in line with the data all the time, and the output bitrate is not related in any way to the EFM data rate off the disc. A good reference for this is Ken Pohlmann's 'The Compact Disc Handbook'.
Cheers!
Howie
Howard Hoyt
CE - WXYC-FM 89.3
UNC Chapel Hill, NC
www.wxyc.org
Optical vs Electrical
Excellent thought, carry it to it's logical conclusion: Your own unaided vision is incapable of seeing such phenomenon such as the size of the Airy pattern of the CD optics which read the CD. How can you test, design, tweak such a system? By photodetectors looking through optics. Since the very CD system itself is designed to turn digital electrical to analog optical and then back to digital electrical, the performance of all the photonic devices involved as a system is what is important.
The parameters you speak of: "Optical Amplitude Modulation" and "Optical Phase Modulation," although they are not called that in the optical disc world, are indeed directly measured and quantified by optical to electrical devices: the testers I linked to. Indeed through experimentation with the standardized instrumentation the complete CD manufacturing and playback system was adjusted for maximum playability, then documented in the Sony/Philips Red Book so that engineers like myself could, by using that same instrumentation, verify and adjust CD mastering and replication parameters to obtain optimum playability.
I'm not sure in this context what you mean by I didn't answer the question. How would you quantify their effect on CD playability?
Cheers!
Howie
Howard Hoyt
CE - WXYC-FM 89.3
UNC Chapel Hill, NC
www.wxyc.org
Excellent thought, carry it to it's logical conclusion: Your own unaided vision is incapable of seeing such phenomenon such as the size of the Airy pattern of the CD optics which read the CD. How can you test, design, tweak such a system? By photodetectors looking through optics. Since the very CD system itself is designed to turn digital electrical to analog optical and then back to digital electrical, the performance of all the photonic devices involved as a system is what is important.
The parameters you speak of: "Optical Amplitude Modulation" and "Optical Phase Modulation," although they are not called that in the optical disc world, are indeed directly measured and quantified by optical to electrical devices: the testers I linked to. Indeed through experimentation with the standardized instrumentation the complete CD manufacturing and playback system was adjusted for maximum playability, then documented in the Sony/Philips Red Book so that engineers like myself could, by using that same instrumentation, verify and adjust CD mastering and replication parameters to obtain optimum playability.
I'm not sure in this context what you mean by I didn't answer the question. How would you quantify their effect on CD playability?
Cheers!
Howie
Howard Hoyt
CE - WXYC-FM 89.3
UNC Chapel Hill, NC
www.wxyc.org
I would go right to one that was "unlistenable" for even 30sec and start there. That would give me an idea about the rest.
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