Re: MD: coax v. toslink
Ralph Smeets wrote: [snip] Sorry "Rat", but you're wrong. I agree that bits are bits. But coax and TosLink don't do error-correction since the S/PDIF protocol doesn't do error-correction. Maybe not, but it does do jitter correction. The S/PDIF lower level protocol is what the computer people call "self clocking". That is, the data stream not only encodes the data stream it also encodes the clock that was used to generate it. The receiver runs a clock generator synchronized to the encoded clock and uses that to decode the data part. This bit stream is then assembled into words, one for each sample, and the words are clock out to the DAC using another clock synchronized to the first clock generator. The draft AES/EBU standard specifies the max clock jitter _at the DAC_ as 1 nanosecond. Most pro equipment will beat that and most consumer equipment won't be too far behind. And none of this depends in the least on what medium is carrying the bit stream. I agree that for recording, it doesn't matter that there is jitter. But before we go any further, I think it's time to explain 'what is jitter'. Jitter is an effect that is caused by the fact that the interval between the samples varies a little. This variation isn't constant. Ie, consider a series of samples: T1, T2, T3 and T4. Let's say they where recorded at 0, 1, 2 and 3 seconds. The value of T1, T2, T3 and T4 equals 1, -1, 1, -1. Ie: 1 @ 0.0 -1 @ 1.0 1 @ 2.0 -1 @ 3.0 So lets play them back. But with some jitter introduced of -0.1 +0.1 +0.1 -0.1. Thus, 1 @ -0.1 -1 @ 1.1 1 @ 2.1 -1 @ 2.9 I think you agree that this series of bits represents another waveform. That's what we call jitter! Cheers, Ralph You're proposing a 10% jitter. The usual 44.1 kHz sample rate is ~22700 nanoseconds/sample. The bit time is roughly 333 ns/bit. The receiving clock will lose sync with the data stream if the bit jitter is 1/2 bit time or 160 ns. Actually, it would be real hard to build a clock generator that would sync up with a jitter of 1/4 or 80 ns. So lets assume an 80ns/bit jitter as a worst case. The samples are transmitted as 32 bit words. The time jitter on a word is (bit jitter)/sqrt(n) or roughly 14 ns. Compared to the the sample time this is .06% absolute worst case. I'll concur with the person who suggested applying green magic marker to the cable. ++PLS - To stop getting this list send a message containing just the word "unsubscribe" to [EMAIL PROTECTED]
Re: MD: coax v. toslink
[EMAIL PROTECTED] wrote: Comparing coaxial and Toslink, there is actually a measurable difference between what you get at the other end of the line. The archives of rec.audio.pro have discussions of this phenomenon, though it's been a number of years since I've kept up with this subject. The issue is "transport jitter", where the timing between the bits varies by some amount (in the range of 5 to 500 picoseconds, if memory serves). The bits received are in fact the same as those that were transmitted, so if you are transporting the bits with the intention of storing them (i.e., on a CD or an MD) it doesn't make a difference what you use. However, when you feed these timing variations into a D/A converter, it can affect the output waveforms. Inside single-box setups, clocking tends to be fairly jitter resistant. It can be a bigger issue if you put together systems with separate transport and D/A sections (e.g., a home theatre surround decoder fed by DVD). It's also an issue for pro audio setups where they have to transport audio around the studio or remote recording location for monitoring. There may have been advances in the past few years that reduce such effects; I'm not sure. Anyhow, Toslink tends to exhibit greater amounts of jitter than coax or other fiber optic media. If you don't hear a difference, don't let it bother you. Romain Kang Siemens Info/Comm Products, San Jose RD [EMAIL PROTECTED] formerly Pyramid Technology Corporation Note that if you buffer the signal, jitter is almost eliminated! Cheers, Ralph -- === Ralph SmeetsFunctional Verification Centre Of Competence - CMG Voice: (+33) (0)4 76 58 44 46 STMicroelectronics Fax:(+33) (0)4 76 58 40 11 5, chem de la Dhuy Mobile: (+33) (0)6 82 66 62 70 38240 MEYLAN E-Mail: [EMAIL PROTECTED] FRANCE === "For many years, mankind lived just like the animals. And then something happened that unleashed the powers of our imagination: We learned to talk." -- Stephen Hawking, later used by Pink Floyd -- === - To stop getting this list send a message containing just the word "unsubscribe" to [EMAIL PROTECTED]
Re: MD: coax v. toslink
[EMAIL PROTECTED] wrote: * [EMAIL PROTECTED] (Romain Kang) on Mon, 03 Apr 2000 | Comparing coaxial and Toslink, there is actually a measurable | difference between what you get at the other end of the line. The | archives of rec.audio.pro have discussions of this phenomenon, though | it's been a number of years since I've kept up with this subject. If it were an analog signal, it would matter. But whether a "1" has an intensity of X or several times X does not change its value one bit :). | The issue is "transport jitter", where the timing between the bits | varies by some amount (in the range of 5 to 500 picoseconds, if memory | serves). Which is compensated by the error correction inherent in the protocol and the data buffering in the receiver. A string of 16 bits is a string of 16 bits, period. In other words, the "audiophiles" are hearing what they want to hear, not what is really getting to their ears. Sorry "Rat", but you're wrong. I agree that bits are bits. But coax and TosLink don't do error-correction since the S/PDIF protocol doesn't do error-correction. I agree that for recording, it doesn't matter that there is jitter. But before we go any further, I think it's time to explain 'what is jitter'. Jitter is an effect that is caused by the fact that the interval between the samples varies a little. This variation isn't constant. Ie, consider a series of samples: T1, T2, T3 and T4. Let's say they where recorded at 0, 1, 2 and 3 seconds. The value of T1, T2, T3 and T4 equals 1, -1, 1, -1. Ie: 1 @ 0.0 -1 @ 1.0 1 @ 2.0 -1 @ 3.0 So lets play them back. But with some jitter introduced of -0.1 +0.1 +0.1 -0.1. Thus, 1 @ -0.1 -1 @ 1.1 1 @ 2.1 -1 @ 2.9 I think you agree that this series of bits represents another waveform. That's what we call jitter! Cheers, Ralph -- === Ralph SmeetsFunctional Verification Centre Of Competence - CMG Voice: (+33) (0)4 76 58 44 46 STMicroelectronics Fax:(+33) (0)4 76 58 40 11 5, chem de la Dhuy Mobile: (+33) (0)6 82 66 62 70 38240 MEYLAN E-Mail: [EMAIL PROTECTED] FRANCE === "For many years, mankind lived just like the animals. And then something happened that unleashed the powers of our imagination: We learned to talk." -- Stephen Hawking, later used by Pink Floyd -- === - To stop getting this list send a message containing just the word "unsubscribe" to [EMAIL PROTECTED]
RE: MD: coax v. toslink
Ralphie explained jitter: So lets play them back. But with some jitter introduced of -0.1 +0.1 +0.1 -0.1. Thus, This is a useful exposition, but in practice, what you may get is: 1 @ -0.0001 -1 @ 1.0001 1 @ 2.1 -1 @ 2.9 the question is, does this make any difference ? These jitters are measured in picoseconds. There are 22 675 737 picoseconds between samples at 44.1 kHz. I think you agree that this series of bits represents another waveform. In the digital domain, it is easy to measure the jitter with suitable equipment. Is there ANYTHING (other than a golden ear) that can measure a difference in the analog output from the D/A as a result of this jitter, even if it isn't reclocked ? simon - To stop getting this list send a message containing just the word "unsubscribe" to [EMAIL PROTECTED]
Re: MD: coax v. toslink
[EMAIL PROTECTED] wrote: Ralphie explained jitter: So lets play them back. But with some jitter introduced of -0.1 +0.1 +0.1 -0.1. Thus, This is a useful exposition, but in practice, what you may get is: 1 @ -0.0001 -1 @ 1.0001 1 @ 2.1 -1 @ 2.9 the question is, does this make any difference ? These jitters are measured in picoseconds. There are 22 675 737 picoseconds between samples at 44.1 kHz. Sorry simon, but there are 2 S/PDIF frames of 32 bits in each sample Ie, 22 675 737 / 64 = 354.3 ns per sample... Hmm, I agree, 1 ps of jitter is probably un-noticable. I think you agree that this series of bits represents another waveform. In the digital domain, it is easy to measure the jitter with suitable equipment. Is there ANYTHING (other than a golden ear) that can measure a difference in the analog output from the D/A as a result of this jitter, even if it isn't reclocked ? I'll try see if I can come up with two FFTs to compare It'll take me some time, probalby the time of my boss Hmmm... Maybee that's not a very bright idea Cheers, Ralph - Trying to spend less time on md-l and more on ST -- === Ralph SmeetsFunctional Verification Centre Of Competence - CMG Voice: (+33) (0)4 76 58 44 46 STMicroelectronics Fax:(+33) (0)4 76 58 40 11 5, chem de la Dhuy Mobile: (+33) (0)6 82 66 62 70 38240 MEYLAN E-Mail: [EMAIL PROTECTED] FRANCE === "For many years, mankind lived just like the animals. And then something happened that unleashed the powers of our imagination: We learned to talk." -- Stephen Hawking, later used by Pink Floyd -- === - To stop getting this list send a message containing just the word "unsubscribe" to [EMAIL PROTECTED]
Re: MD: coax v. toslink
* Ralph Smeets [EMAIL PROTECTED] on Tue, 04 Apr 2000 | I agree that bits are bits. But coax and TosLink don't do error-correction | since the S/PDIF protocol doesn't do error-correction. I know, and I apologise for misusing the term, because what is going on in the receiver is not really error correction per se. -- Rat [EMAIL PROTECTED]\ Happy Fun Ball contains a liquid core, Minion of Nathan - Nathan says Hi! \ which, if exposed due to rupture, should PGP Key: at a key server near you! \ not be touched, inhaled, or looked at. - To stop getting this list send a message containing just the word "unsubscribe" to [EMAIL PROTECTED]
Re: MD: coax v. toslink
* [EMAIL PROTECTED] (Romain Kang) on Mon, 03 Apr 2000 | Comparing coaxial and Toslink, there is actually a measurable | difference between what you get at the other end of the line. The | archives of rec.audio.pro have discussions of this phenomenon, though | it's been a number of years since I've kept up with this subject. If it were an analog signal, it would matter. But whether a "1" has an intensity of X or several times X does not change its value one bit :). | The issue is "transport jitter", where the timing between the bits | varies by some amount (in the range of 5 to 500 picoseconds, if memory | serves). Which is compensated by the error correction inherent in the protocol and the data buffering in the receiver. A string of 16 bits is a string of 16 bits, period. In other words, the "audiophiles" are hearing what they want to hear, not what is really getting to their ears. -- Rat [EMAIL PROTECTED]\ Ingredients of Happy Fun Ball include an Minion of Nathan - Nathan says Hi! \ unknown glowing substance which fell to PGP Key: at a key server near you! \ Earth, presumably from outer space. - To stop getting this list send a message containing just the word "unsubscribe" to [EMAIL PROTECTED]
Re: MD: coax v. toslink
- Original Message - From: Jim Gray [EMAIL PROTECTED] To: md [EMAIL PROTECTED] Sent: Monday, April 03, 2000 10:17 AM Subject: MD: coax v. toslink Can someone please explain to me how there could possibly be any difference between digital transmission by coaxial versus TosLink? I would assume that the exact same data is transferred, and that error correction would insure that no data is lost, and yet I read in this high-end stereophile book a statement that toslink gives inferior bass and imaging, or some such. Is this for real? Opticals better as far as Im concerned as it provides electrical isolation between the components - if I hook a cable between my PC and stereo I get a whining noise from a groundloop. If I use optical - no problems. - To stop getting this list send a message containing just the word "unsubscribe" to [EMAIL PROTECTED]
RE: MD: coax v. toslink
One word ... BULLSHIT! Yes, optical is less susceptible to interference compared to coax (since it is light and not influenced by surrounding electrical noise, magnetic fields, etc.). But the difference is so minuscule, honestly, it's not an audible difference. Screw test gear and whatnot, it's your ears that are the recipients of the end result. Take a listen for yourself and you tell me if you hear anything different! Adios, LarZ --- TAMA - The Strongest Name in Drums --- -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]] On Behalf Of Jim Gray Sent: Monday, 3 April 2000 8:17 To: md Subject:MD: coax v. toslink Can someone please explain to me how there could possibly be any difference between digital transmission by coaxial versus TosLink? I would assume that the exact same data is transferred, and that error correction would insure that no data is lost, and yet I read in this high-end stereophile book a statement that toslink gives inferior bass and imaging, or some such. Is this for real? - To stop getting this list send a message containing just the word "unsubscribe" to [EMAIL PROTECTED]
Re: MD: coax v. toslink
At 18:17 02/04/00 -0400, you wrote: Can someone please explain to me how there could possibly be any difference between digital transmission by coaxial versus TosLink? I would assume that the exact same data is transferred, and that error correction would insure that no data is lost, and yet I read in this high-end stereophile book a statement that toslink gives inferior bass and imaging, or some such. Is this for real? Absolute bulls***. Digital is digital, no matter what medium you transmit it through. It's the same signal travelling through the medium - the only difference being that with co-ax it's in an electrical form, whereas with fibre, it's in the form of light pulses. Optic fibre is totally immune to electrical interference, but transmission distance can be dependant on the quality of fibre, terminations, etc. Both are perfectly fine for everyday hi-fi/computer use. AES/EBU, which is where S/PDIF came from, uses a twisted-pair balanced line to send the same kind of information, but because of the noise immunity characteristics of twisted-pair transmission lines, and the specification requirements of the AES/EBU standard, the data can be transmitted over a much greater distance than co-ax S/PDIF. I really wish people wouldn't write such rubbish in books - I can't believe people think it's possible for an optical connection to have inferior bass response. It's the same with these expensive interconnects and speaker cables - interconnects are interconnects, no matter whether they cost 2 quid or 2000 quid, and the best speaker cable in the world is mains cable (2.5mm twin + earth is ideal). That's another topic altogether... Chrz, Wrighty ___ _ ___ | | | | | o |=| o | | | Richard Wright - [EMAIL PROTECTED] | | | o |-| o | | | __ __ __ __ ____ | | | o | | | | ||__|| |__| |_ __ _ | o | | | | | | | _| | _ | | __| | | | | | o | ||__| |__|___ |__|__||___ | | o | | | || || | | | o |-| o | | | Find me on ICQ - UIN: 4050545 (http://www.icq.com) | | | o |=| o | |___|_|___| - To stop getting this list send a message containing just the word "unsubscribe" to [EMAIL PROTECTED]
Re: MD: coax v. toslink
=== = NB: Over 50% of this message is QUOTED, please = = be more selective when quoting text = === At 06:17 2/04/00 -0400, Jim Gray wrote: Can someone please explain to me how there could possibly be any difference between digital transmission by coaxial versus TosLink? I would assume that the exact same data is transferred, and that error correction would insure that no data is lost, and yet I read in this high-end stereophile book a statement that toslink gives inferior bass and imaging, or some such. Is this for real? it's their permannet april fools joke - To stop getting this list send a message containing just the word "unsubscribe" to [EMAIL PROTECTED]
Re: MD: coax v. toslink
It is BS, and gives you an idea of what the people that write for the magazine think of the intelligence of their readers. Sort of the National Enquirer of magazines I guess. Jim Gray wrote: Can someone please explain to me how there could possibly be any difference between digital transmission by coaxial versus TosLink? I would assume that the exact same data is transferred, and that error correction would insure that no data is lost, and yet I read in this high-end stereophile book a statement that toslink gives inferior bass and imaging, or some such. Is this for real? -- Jim Coon Not just another pretty mandolin picker. mailto:[EMAIL PROTECTED] If Gibson made cars, would they sound so sweet? My first web page http://www.tir.com/~liteways - To stop getting this list send a message containing just the word "unsubscribe" to [EMAIL PROTECTED]
