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CD transports and resonance
On Sat, 6 Nov 2004 19:49:08 -0000, "Rob"
wrote: "Stewart Pinkerton" wrote in message .. . On 06 Nov 2004 15:15:40 GMT, ohawker (Andy Evans) wrote: To resolve, employ suitable measurements. Otherwise we (including you) have no real idea if the effects you describe have anything to do with the 'causes' you assume. Hello Jim - I'm open minded - my assumption is that it's to do with resonance, I suppose, but I've been very clear in saying I don't understand how this happens. I'm not in a position to measure, so my next step is to find others who have observed similar things and others who can offer some kind of explanation based on their own empirical knowledge. Andy Actually, your assumption is that there *is* a real effect. -- No, I read that as a finding. The assumption - and I think it's not unreasonable - is that stabilising a cd mechanism brings audible benefits. I would find that assumption reasonable, in the sense that it's worthy of test, because of the massive engineering you see in some CDPs and stated preferences for particular mechanisms. I have no idea why, btw, but I'd be curious if I could be bothered. Basic scientific research - first, you have to establish that there actually *is* an effect, before looking for a cause. Easiest way has already been suggested, just rip a file with audio off, one with audio on, and another pair with the transport bonded to a large mass. If all four files are identical, forget the 'problem', and do something useful, like improve your room. -- Stewart Pinkerton | Music is Art - Audio is Engineering |
CD transports and resonance
On Sat, 6 Nov 2004 19:42:58 -0000, "Rob"
wrote: "Stewart Pinkerton" wrote in message .. . On 06 Nov 2004 11:27:16 GMT, ohawker (Andy Evans) wrote: I have no wish to 'endow' (DP) anything. I'm reporting less distortion in highly modulated passages when a transport is damped. No, you're reporting that you *think* something is happening. You have as yet shown no indication that anything *real* is occuring. -- If I were Andy I'd be feeling like someone asked to prove, for ever, evidence of something that doesn't exist in the empirical world. Andy can't prove what he hears, and I'm inclined to think he (of all people) is aware of placebo-type effects. Why can't you turn this round - instead of asking him to prove it, you disprove it. Why? Because common sense and engineering knowledge suggests that there is no physical effect occuring. Hence, it's up to the person making the extraordinary claim to provide proof of his claim. We've seen the 'but I *heard* it!' claim far too often for things like cables, to simply accept it on faith. Simple hypothesis - test it and see what happens. Exactly! Just rip files from that transport in the four sensible conditions - music on and off, large 'damping' mass attached and not attached. Check to see if the files differ. If they do, investigate. If they don't, forget it. -- Stewart Pinkerton | Music is Art - Audio is Engineering |
CD transports and resonance
In article , Andy Evans
wrote: To resolve, employ suitable measurements. Otherwise we (including you) have no real idea if the effects you describe have anything to do with the 'causes' you assume. Hello Jim - I'm open minded - my assumption is that it's to do with resonance, I suppose, I see no reason from what you say to assume it is "resonance" rather than, for example, simple vibration effects, or a fault of some kind. but I've been very clear in saying I don't understand how this happens. I'm not in a position to measure, so my next step is to find others who have observed similar things and others who can offer some kind of explanation based on their own empirical knowledge. Andy The difficulty is that you are hampered in your desire to find others "who have observed similar things" by only having an unspecific impression of a possible symptom. Without relevant measurements or tests you can't assume that someone who thinks they have heard something similar is actually experinencing the same causal mechanism at work. The bottom line, I'm afraid, is that if you do development work without the relevant measurement kit and being able to study/understand the implications of the measured results, then you can expect to be 'at sea' at such times. Finding someone else who is also 'at sea' may be comforting, but may not help much. Slainte, Jim Slainte, Jim -- Electronics http://www.st-and.ac.uk/~www_pa/Scot...o/electron.htm Audio Misc http://www.st-and.demon.co.uk/AudioMisc/index.html Armstrong Audio http://www.st-and.demon.co.uk/Audio/armstrong.html Barbirolli Soc. http://www.st-and.demon.co.uk/JBSoc/JBSoc.html |
CD transports and resonance
you will keep encountering effects which will seem like "mysteries of science"
until you put the required time and effort into tests and evidence that would allow a systematic explanation. Without this info, there is not much others can guess. (JL) That's a completely reasonable point. I've already pointed out some real world considerations, however. I do have a scope but I've never used it yet, and I have a raft of things that will come before that as a matter of urgency. For those without scopes - and there are a few on this ng - reports of building experiments will be aural. That's a fact of life. Now, commonly builders report on projects for many reasons: a) to get help if things go wrong b) to report particular changes which appear to be sonic improvements in case others want to consider or try them.This may not be any more significant than "I heard this, don't really know why" c) in motivational terms to get support and positive feedback from fellow enthusiasts for several hours at the drill press and soldering iron. This is completely reasonable. And, of course such reports meet with a variety of answers. If I were personally to divide these into 'reasonable' and 'unreasonable' I'd do so roughly as follows: Reasonable: - I can't help you - you haven't given enough information - I personally doubt very much that this is possible - This goes entirely against what I have found - Are you sure you are not confusing two or more variables Unreasonable: - You did not hear what you say you did - Clearly you are deluded and hearing things - You are an idiot - I am vastly cleverer and more technically qualified than you so anything I say is better than anything you say. I think you get what I mean. Thanks for the reply, Jim. Andy === Andy Evans === Visit our Website:- http://www.artsandmedia.com Audio, music and health pages and interesting links. |
CD transports and resonance
In article , Andy Evans
wrote: I'm afraid that I'm a bit sceptical about some of the product designers (mick) I don't think it's the product designers so much as the tweakers. I'm sceptical myself - it seems paradoxical that resonance can effect binary code. The answer to the apparent paradox would rest in being able to actually *check* the binary stream emerging from the player. Once done, this may or may not show some differences.... Slainte, Jim -- Electronics http://www.st-and.ac.uk/~www_pa/Scot...o/electron.htm Audio Misc http://www.st-and.demon.co.uk/AudioMisc/index.html Armstrong Audio http://www.st-and.demon.co.uk/Audio/armstrong.html Barbirolli Soc. http://www.st-and.demon.co.uk/JBSoc/JBSoc.html |
CD transports and resonance
On Sat, 6 Nov 2004 20:22:49 -0000, "Rob"
wrote: There is a chance - that is, er, the point. It may be slim but I find an inquiring mind fascinating. How many massive breakthroughs to our understanding of the physical world have been made by people who were told 'Nope, it's impossible'. Challenge hegemony. Indeed so. Challenge it by establishing the existence of a real effect, for starters. As has been pointed out, since the transport outputs a digital data stream, not audio, this is very simple to do with any PC. -- Stewart Pinkerton | Music is Art - Audio is Engineering |
CD transports and resonance
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CD transports and resonance
CD transports are designed to tolerate such stuff ( vibration et al ). How on
earth do you think one can work in a car otherwise ? Hello there - I never said it didn't work - that's not the issue. Also the changes are subtle, and not something you'd have a hope in hell of hearing in a car. As I've constantly said, this is quite paradoxical. === Andy Evans === Visit our Website:- http://www.artsandmedia.com Audio, music and health pages and interesting links. |
CD transports and resonance
Jim says: "we have no assurance that your descriptions are a reliable guide
to what actually may be occurring." That's entirely correct. Andy === Andy Evans === Visit our Website:- http://www.artsandmedia.com Audio, music and health pages and interesting links. |
CD transports and resonance
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CD transports and resonance
"Stewart Pinkerton" wrote in message ... On Sat, 6 Nov 2004 19:42:58 -0000, "Rob" wrote: "Stewart Pinkerton" wrote in message . .. On 06 Nov 2004 11:27:16 GMT, ohawker (Andy Evans) wrote: I have no wish to 'endow' (DP) anything. I'm reporting less distortion in highly modulated passages when a transport is damped. No, you're reporting that you *think* something is happening. You have as yet shown no indication that anything *real* is occuring. -- If I were Andy I'd be feeling like someone asked to prove, for ever, evidence of something that doesn't exist in the empirical world. Andy can't prove what he hears, and I'm inclined to think he (of all people) is aware of placebo-type effects. Why can't you turn this round - instead of asking him to prove it, you disprove it. Why? Because common sense and engineering knowledge suggests that there is no physical effect occuring. Hence, it's up to the person making the extraordinary claim to provide proof of his claim. We've seen the 'but I *heard* it!' claim far too often for things like cables, to simply accept it on faith. Simple hypothesis - test it and see what happens. Exactly! Just rip files from that transport in the four sensible conditions - music on and off, large 'damping' mass attached and not attached. Check to see if the files differ. If they do, investigate. If they don't, forget it. No no no SP! Try it my way, in a measured manner. Or, is the 'data-on-the-disk' the *only* thing that matters in this context? If it is, you've run out of avenues and reached the sides of your box. No problem with that. Just say, sorry Andy, I don't know. (Having said this, the data might be different!) Rob |
CD transports and resonance
John Philips) Thank you John for an interesting post. In response to your
question, my CD-rom is a Creative 36X-mx. I don't know if it is single or three beam - it's probably ten years old I think. Andy === Andy Evans === Visit our Website:- http://www.artsandmedia.com Audio, music and health pages and interesting links. |
CD transports and resonance
On Sat, 06 Nov 2004 20:13:49 +0000 (GMT), "Dave Plowman (News)"
wrote: In article , Rob wrote: Andy can't prove what he hears, and I'm inclined to think he (of all people) is aware of placebo-type effects. Yet is continually offering up for comments things he can 'hear' that others wouldn't. And thinks that SS amps somehow remove something from the music which valve amps retain, while all available evidence shows that 'valve' sound is simply *added* artifacts. Perhaps he doesn't like to apply his working scientific rigour to his playtime pursuits............ -- Stewart Pinkerton | Music is Art - Audio is Engineering |
CD transports and resonance
In article , Rob
wrote: "Stewart Pinkerton" wrote in message ... On 06 Nov 2004 11:27:16 GMT, ohawker (Andy Evans) wrote: I have no wish to 'endow' (DP) anything. I'm reporting less distortion in highly modulated passages when a transport is damped. No, you're reporting that you *think* something is happening. You have as yet shown no indication that anything *real* is occuring. -- If I were Andy I'd be feeling like someone asked to prove, for ever, evidence of something that doesn't exist in the empirical world. Andy can't prove what he hears, and I'm inclined to think he (of all people) is aware of placebo-type effects. Why can't you turn this round - instead of asking him to prove it, you disprove it. Simple hypothesis - test it and see what happens. Alternatively, lets ask for some evidence that might help one way or the others. e.g.s 1) Perform the test Ian has suggested. Play the same CD twice, and read the bitstream and compare the bit/sample patterns. If they are the same we can then conclude that the player is reliably reading the actual data and feeding it to the DAC as the same series of values in each case. 2) If the result of the above shows the same patterns in each case. Repeat with a suitable CD-A that would show up dither as sidebands/intermod on the replayed waveform. Collect two copies again, and compare. If they are the same, we can then reasonably think that the CDROM is feeding the same data in the same way to the DAC in each case. Hence by carrying out the above tests we would be able to get some idea if Andy's belief that he can hear a difference is supported by tests. If the test do show a difference, then the results would aid us in suggesting a solution. However if both tests show no changes that correlate with the cause he is suggesting we can reasonably assume that he is mistaken in some way. I suspect that behind your rather abrupt manner and bluster is a charitable soul trying to dissuade people from throwing time and money at what you see to be a pointless grail. I can't prove it though ;-). Can't speak for Stewart. My intention is to encourage/help people to develop in a more systematic manner, based upon developing a more reliable understanding of what is actually going on. Doing this by performing relevant tests whose results can be used for this purpose. The problem at the moment is that I/we can make *guesses* as to what might be happening, but without relevant data these remain just guesswork. The Scientific Method has been around for some time now. My recommendation is to employ it for questions like this. Might help a bit... :-) Slainte, Jim -- Electronics http://www.st-and.ac.uk/~www_pa/Scot...o/electron.htm Audio Misc http://www.st-and.demon.co.uk/AudioMisc/index.html Armstrong Audio http://www.st-and.demon.co.uk/Audio/armstrong.html Barbirolli Soc. http://www.st-and.demon.co.uk/JBSoc/JBSoc.html |
CD transports and resonance
In article , Rob
wrote: "Stewart Pinkerton" wrote in message ... On 06 Nov 2004 15:15:40 GMT, ohawker (Andy Evans) wrote: To resolve, employ suitable measurements. Otherwise we (including you) have no real idea if the effects you describe have anything to do with the 'causes' you assume. Hello Jim - I'm open minded - my assumption is that it's to do with resonance, I suppose, but I've been very clear in saying I don't understand how this happens. I'm not in a position to measure, so my next step is to find others who have observed similar things and others who can offer some kind of explanation based on their own empirical knowledge. Andy Actually, your assumption is that there *is* a real effect. -- No, I read that as a finding. No, the 'finding' is that Andy thinks he hears a difference. This does not mean that we have 'found' either that the effect is produced by 'resonance' or to the actual CD player. To establish that, more tests of a systematic and controlled nature would be required. The assumption - and I think it's not unreasonable - is that stabilising a cd mechanism brings audible benefits. As a vague and unspecific generalisation that is fine. However it does not establish that this *is* the case in this specific instance. For that we require suitable tests to obtain relevant evidence. I would find that assumption reasonable, in the sense that it's worthy of test, because of the massive engineering you see in some CDPs and stated preferences for particular mechanisms. I have no idea why, btw, but I'd be curious if I could be bothered. Agreed. FWIW as I've already pointed out earlier in this thread, I have also had reason to find that applying samping to quite a decent transport caused what I feel was a slight but audible improvement. However this was for reasons quite different to those being assumed here! I also think it possible that I was mistaken, being human. Slainte, Jim -- Electronics http://www.st-and.ac.uk/~www_pa/Scot...o/electron.htm Audio Misc http://www.st-and.demon.co.uk/AudioMisc/index.html Armstrong Audio http://www.st-and.demon.co.uk/Audio/armstrong.html Barbirolli Soc. http://www.st-and.demon.co.uk/JBSoc/JBSoc.html |
CD transports and resonance
Pooh Bear wrote:
There's a lot of error correction capability on a CD. Hamming encoded IIRC. Forget how many bits of error it can correct transparently. Philips / Sony expected early CDs to have lots of errors so needed them to be correctable. Actually, CD uses a form of the Reed Solomon code. Though the Hamming code would provide error correction as well. |
CD transports and resonance
Jim wrote: "The subjective 'discription' you give has no clear information
content for anyone who was not using your ears at the time, or who does not already by some other means know exactly what you are talking about.This does not mean that we can all be certain the difference is entirely imaginary. Simply that we have no real way of telling much beyond noting that you think you hear something. That's entirely correct, and well put. We do know incontravertibly that I fastened a 10mm slab of alu size 6.5" by 9.5" with four 3M bolts to the underside of a Creative 36X-xm CD-Rom, sat down in what I took to be the same listening position after the delay it took to bolt the slab on, and listened to the same test tracks again. The rest, as you say, we don't know accurately. Andy === Andy Evans === Visit our Website:- http://www.artsandmedia.com Audio, music and health pages and interesting links. |
CD transports and resonance
In article , Dave Plowman (News)
wrote: In article , Rob wrote: The assumption - and I think it's not unreasonable - is that stabilising a cd mechanism brings audible benefits. It would do if a record player. They can suffer from all sorts of vibration influenced effects. But a CD player is surprisingly digital. Assuming that digital signal can still be read it will work normally. If it is subjected to severe vibration it will stop - or at least produce some alarming noises. Nothing really in between. In principle this is not quite correct. Vibration and other effects may cause some data loss at the reading level. Most of this will be corrected by the redundancy, etc. But there is a risk that occasional sample values with be incorrect. In a decent player, with a decent disc, this should be very rare. But in an unknown transport with dubious support it may become more common. In principle, a CDROM drive can repeatedly re-read, but even then, something might go wrong. The difficulty, though, is that without some reliable and relevant evidence we have no way to know if this is happening in Andy's case. Thus given that the CD system is designed to work OK when vibration, etc, *are* present at some level, we can't take it as established that this is a cause in this case. Slainte, Jim -- Electronics http://www.st-and.ac.uk/~www_pa/Scot...o/electron.htm Audio Misc http://www.st-and.demon.co.uk/AudioMisc/index.html Armstrong Audio http://www.st-and.demon.co.uk/Audio/armstrong.html Barbirolli Soc. http://www.st-and.demon.co.uk/JBSoc/JBSoc.html |
CD transports and resonance
Rob wrote:
"Stewart Pinkerton" wrote in message ... Exactly! Just rip files from that transport in the four sensible conditions - music on and off, large 'damping' mass attached and not attached. Check to see if the files differ. If they do, investigate. If they don't, forget it. No no no SP! Try it my way, in a measured manner. Or, is the 'data-on-the-disk' the *only* thing that matters in this context? If it is, you've run out of avenues and reached the sides of your box. No problem with that. Just say, sorry Andy, I don't know. (Having said this, the data might be different!) Rob Rob, getting the 'data off the disk' in a reliable manner is the only thing that matters in this context. If the output stream of 1s and 0s from an undamped and damped transport is exactly the same, then the damping doesn't make a difference. |
CD transports and resonance
On 07 Nov 2004 03:04:58 GMT, John Phillips
wrote: In article , Ian Molton wrote: will you accept that two identical bitstreams will reproduce identically through a given DAC? It is not clear if this include timing as well as data. Timing doesn't matter, if it's a competent DAC. I assume both. However, for the sake of clarity if the jitter on the bitstreams were different and the DAC merely replicated the incoming clock on its D/A converter there could be an audible difference. This is solved by using a competent DAC, not messing with the already competent transport. Contrariwise, a good DAC (from an engineering POV anyway) will deal properly with input jitter up to some level and have a D/A converter clock whose jitter is independent. (Although the threshold of audibility of jitter was still not well established the last time I looked - but this might have changed as it was a long time ago). Quite so. Nevertheless there is a hypothesis which could be tested which could explain Andy's observation. Indeed so, but Andy seems uninterested in investigating the probability that there is nothing to hear. If so I can disprove andys theory by ripping a CD on my PC at 30ish speed and comparing the bitstreams. I've done this before, with some pretty manky CDs, and have successfully extracted identical bitstreams on two consecutive runs. There may be some quirks to consider here too. AIUI, a few years ago only CD-ROM transports used to have three-beam lasers (as opposed to CD-DA transports with a single beam) and were reported to have rather lower first-stage soft read error rates due to better tracking of the CD. So, maybe there is a hypothesis to test here concerning the error performance of the CD transport. This may well have been behind Meridian's use of CD-ROM transports in their CD players years ago when others were still using CD-DA transports. This seems to have changed over the last few years as many audio CD players have come to use three-beam transports too. However, for low enough raw error rates (hard plus soft) this should all get corrected anyway (although, again, CD-DA format error correction is not as good as CD-ROM format error correction). My experience recovering the data from physically damanged audio CDs is the same as Ian M's: until a CD is really bad, multiple extractions on a three-beam CD-ROM transport produce completely identical bitstreams (I'm not including timing here). I have not followed the thread well enough to recall just what CD transport was being used for Andy's initial observation but it is certainly my observation that some transports are audibly worse than others with damaged CDs. I can demonstrate that with the three current transports I have (four including the car player). However I can also demonstrate to myself that the additional vibration isolation I have tried (not the same thing as Andy tried) on my main CD player - a three-beam transport - makes no audible difference for all CDs I have tested (including the damaged ones). Andy does not however seem to be interested in such testing, so what to do? -- Stewart Pinkerton | Music is Art - Audio is Engineering |
CD transports and resonance
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CD transports and resonance
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CD transports and resonance
On Sun, 07 Nov 2004 06:51:16 +0000, Dodge McRodgered
wrote: "Dave Plowman (News)" emitted : there's no assurance that there is in fact an audible phenomenon. Apart from the fact that I can hear it. I'm afraid that's only a 'fact' to you. To be certain it's not just your imagination requires proper testing. Fooling oneself that a 'tweak' produces an audible improvement is as old as tweaks themselves. Even if that's the case, you accept that Andy "hears" what he says he can hear? Is that what the voices tell you? :-) -- Stewart Pinkerton | Music is Art - Audio is Engineering |
CD transports and resonance
In article , Andy Evans
wrote: All it takes is for somebody independent to change between two sources in a random fashion.(snip).. the minimum you would do before even considering reporting to the world. Hello Don - now, are you seriously suggesting that I buy another identical transport (which is an obsolete model), set up a switching device and go out of my way to get a third party to operate it just in order to make an observation to a recreational newsgroup? I had thought you were asking for advice and information on the possible cause of what you beleive you hear, and by implication, how it could best be dealt with. To do this, you require suitable evidence you can give to others. Some parties on this newsgroups seem to think that before stating anything you should set up a complex DBT which would probably take several days of one's time and require a variety of equipment and third parties. Now if I were saying "I have discovered something new, I'm confident that I'm the first to discover it and I'll be applying for a patent this week and sending my findings to three scientific journals once validation is complete" - then, and only then, would I consider that such demands for DBTs etc had any place on a recreational newsgroup. Andy Not really a question of "discovering something new" but of testing if you have discovered anything at all, and if so, what. Slainte, jim -- Electronics http://www.st-and.ac.uk/~www_pa/Scot...o/electron.htm Audio Misc http://www.st-and.demon.co.uk/AudioMisc/index.html Armstrong Audio http://www.st-and.demon.co.uk/Audio/armstrong.html Barbirolli Soc. http://www.st-and.demon.co.uk/JBSoc/JBSoc.html |
CD transports and resonance
In article , Andy Evans
wrote: Bolting a plate to the case is likely to alter the resonance of *that case*. Why should that make a difference to the drive or electronics? (DP) Hello Dave - that's exactly the question I'm asking. To find an answer, you have to perform the relevent tests, and collect the data which you can then use as a basis for understanding. Your choice if you wish to do this or not. I, and others, have suggested some test methods that seem relevant. Up to you to choose to employ them or not. However if you can't be bothered, then why ask for help? Slainte, Jim -- Electronics http://www.st-and.ac.uk/~www_pa/Scot...o/electron.htm Audio Misc http://www.st-and.demon.co.uk/AudioMisc/index.html Armstrong Audio http://www.st-and.demon.co.uk/Audio/armstrong.html Barbirolli Soc. http://www.st-and.demon.co.uk/JBSoc/JBSoc.html |
CD transports and resonance
In article , John Phillips
wrote: In article , Ian Molton wrote: There may be some quirks to consider here too. AIUI, a few years ago only CD-ROM transports used to have three-beam lasers (as opposed to CD-DA transports with a single beam) and were reported to have rather lower first-stage soft read error rates due to better tracking of the CD. My understanding is that the Philips mechanisms for CD-A started off with single beam dither tracking, but the Sony ones started as three-beam. I think this continued for many years, but am less sure of that. So, maybe there is a hypothesis to test here concerning the error performance of the CD transport. This may well have been behind Meridian's use of CD-ROM transports in their CD players years ago when others were still using CD-DA transports. This seems to have changed over the last few years as many audio CD players have come to use three-beam transports too. My understanding is that they stayed with the transports they were familiar with as they'd put a lot of work into developing their own in-house servo control software, etc. So far as I know, the main distinction, though was not between dither tracking and 3-beam, but between x1 and xN with re-reads. However, for low enough raw error rates (hard plus soft) this should all get corrected anyway (although, again, CD-DA format error correction is not as good as CD-ROM format error correction). My experience recovering the data from physically damanged audio CDs is the same as Ian M's: until a CD is really bad, multiple extractions on a three-beam CD-ROM transport produce completely identical bitstreams (I'm not including timing here). My experience is the same as the above. I have not followed the thread well enough to recall just what CD transport was being used for Andy's initial observation but it is certainly my observation that some transports are audibly worse than others with damaged CDs. I can demonstrate that with the three current transports I have (four including the car player). My experience is similar. Indeed, I have had some faulty discs which produced quite obvious clicks/pops/swishes in one player but not another. This included players like the Quad 67 and the Meridian 200/263. However I can also demonstrate to myself that the additional vibration isolation I have tried (not the same thing as Andy tried) on my main CD player - a three-beam transport - makes no audible difference for all CDs I have tested (including the damaged ones). My experience is the same as the above. I *have* felt that damping can help, but for reasons that do not have anything to do with the actual digital output of the transport. Slainte, Jim -- Electronics http://www.st-and.ac.uk/~www_pa/Scot...o/electron.htm Audio Misc http://www.st-and.demon.co.uk/AudioMisc/index.html Armstrong Audio http://www.st-and.demon.co.uk/Audio/armstrong.html Barbirolli Soc. http://www.st-and.demon.co.uk/JBSoc/JBSoc.html |
CD transports and resonance
On Sun, 07 Nov 2004 09:27:06 +0000, Pooh Bear
wrote: mick wrote: I read somewhere (sorry, can't give a ref) that the error correction on transports intended for audio is more lax than on those intended for data, as your ears are incapable of detecting low error rates but are more sensitive to the gaps caused by error correction. If that is so, then using a data drive for audio may give a different sound, but not one that is necessarily "better" as it will contain a different sort of inaccuracy! I'm sure someone will be able to correct me on this if I'm wrong. There's a lot of error correction capability on a CD. Hamming encoded IIRC. Forget how many bits of error it can correct transparently. Philips / Sony expected early CDs to have lots of errors so needed them to be correctable. Bear in mind that it was expected that early CDs would *need* error correction. I'm sure they are much better now. I can't recall if the CD standard includes 'error concealment'. Anyone know ? It does. Uncorrected errors may be concealed, i.e. the system takes a 'best guess' at what the missing sample(s) should have been, or unconcealed 'mute' errors where the output is silenced - usually for less than a millisecond. The general consensus is that with a standard commercial CD you get one sub-millisecond concealed error about once every five minutes, and somewhat less than one 'mute' error per disc. Anyone here think that either of those will be audible? Otherwise, the datastream is *perfect*. -- Stewart Pinkerton | Music is Art - Audio is Engineering |
CD transports and resonance
On Sun, 07 Nov 2004 21:07:43 +1100, Tat Chan
wrote: Rob wrote: "Stewart Pinkerton" wrote in message ... Exactly! Just rip files from that transport in the four sensible conditions - music on and off, large 'damping' mass attached and not attached. Check to see if the files differ. If they do, investigate. If they don't, forget it. No no no SP! Try it my way, in a measured manner. Or, is the 'data-on-the-disk' the *only* thing that matters in this context? Sure it is - what else would possibly matter in a device which outputs a digital datastream? That's what makes this such an easy thing to verify! If it is, you've run out of avenues and reached the sides of your box. It's a box which has been well defined for twenty years - as has auditory hallucination and expectation effects, which Andy *should* know about, but is conveniently ignoring. Shrink, shrink thyself! Also, Andy is reporting audio-related effects from a device which outputs a coded datastream which is not in any direct way related to the final audio signal. No problem with that. Just say, sorry Andy, I don't know. (Having said this, the data might be different!) Indeed it might, but this would indicate a seriously underperforming transport. Rob, getting the 'data off the disk' in a reliable manner is the only thing that matters in this context. If the output stream of 1s and 0s from an undamped and damped transport is exactly the same, then the damping doesn't make a difference. Quite so, also if it is not affected by acoustic feedback from loud music playing. Heck, put the damn thing right in front of the speakers if you like! -- Stewart Pinkerton | Music is Art - Audio is Engineering |
CD transports and resonance
In article , Rob
wrote: I have absoltely no technical understanding of the issue. I've read a few articles and follow Jim Lesurf's contributions with interest. JL is probably the most qualified to explain things from the technical/quantitative/positivist viewpoints Dunno about that. My views should be treated as being as potentially fallible, just like anyone else's. :-) - and you will note his reply in this context is slightly equivocal - there is 'wiggle room' - and, IIRC, he is/has been a user of dedicated transports, although this may have been to do with DACs, can't remember. There are some 'potential' problems with data recovery, jitter, etc. However: 1) They should not really matter in decent players, with decent discs, etc. 2) Can't reliably assess anything about Andy's reports without relevant data. Slainte, Jim -- Electronics http://www.st-and.ac.uk/~www_pa/Scot...o/electron.htm Audio Misc http://www.st-and.demon.co.uk/AudioMisc/index.html Armstrong Audio http://www.st-and.demon.co.uk/Audio/armstrong.html Barbirolli Soc. http://www.st-and.demon.co.uk/JBSoc/JBSoc.html |
CD transports and resonance
In article , Pooh Bear
wrote: mick wrote: I read somewhere (sorry, can't give a ref) that the error correction on transports intended for audio is more lax than on those intended for data, as your ears are incapable of detecting low error rates but are more sensitive to the gaps caused by error correction. If that is so, then using a data drive for audio may give a different sound, but not one that is necessarily "better" as it will contain a different sort of inaccuracy! I'm sure someone will be able to correct me on this if I'm wrong. There's a lot of error correction capability on a CD. Hamming encoded IIRC. Forget how many bits of error it can correct transparently. Philips / Sony expected early CDs to have lots of errors so needed them to be correctable. Bear in mind that it was expected that early CDs would *need* error correction. I'm sure they are much better now. I can't recall if the CD standard includes 'error concealment'. Anyone know ? Nominally left to the player. The system will use the redundancy to correct errors. Where the relevant correction data is inconsistent and this can't be resolved interpolation may be employed. Details at the choice of the player manufacturer. The German broadcaster WDR ( IIRC) found that subjective differences between *DAT* transports was due to head misalignment causing error concealment to kick in. Some units suffered more than others. Error *concealment* kicks in when there aren't enough valid bits to transparently *correct*. Error *concealment* is *not* audibly transparent. I doubt that CDs are troubled by this though. In general, I'd agree. But I have enountered some CDs where the error levels produce obvious audible problems in some/all players. In my experience this is rare, though. Slainte, Jim -- Electronics http://www.st-and.ac.uk/~www_pa/Scot...o/electron.htm Audio Misc http://www.st-and.demon.co.uk/AudioMisc/index.html Armstrong Audio http://www.st-and.demon.co.uk/Audio/armstrong.html Barbirolli Soc. http://www.st-and.demon.co.uk/JBSoc/JBSoc.html |
CD transports and resonance
In article , Andy Evans
wrote: you will keep encountering effects which will seem like "mysteries of science" until you put the required time and effort into tests and evidence that would allow a systematic explanation. Without this info, there is not much others can guess. (JL) That's a completely reasonable point. I've already pointed out some real world considerations, however. I do have a scope but I've never used it yet, and I have a raft of things that will come before that as a matter of urgency. For those without scopes - and there are a few on this ng - reports of building experiments will be aural. That's a fact of life. Not really. It is a choice that you (and some others) make. My own choice is to develop and test using appropriate test gear and diagnosis methods *as well as* listening. Also to base development on trying to understand what is actually happening in terms of the physics and engineering involved. I'm afraid, though, that the situation remains that many such things may well remain 'mysteries' to you until such time as you proceed in more systematic manner in collecting relevant data. Until then, I'm afraid that your asking for 'help' isn't useful when you then disregard what actual help is offerred. The 'help' I can offer is to explain how you can investigate. Your choice to use this, or disregard it. But if you disregard it, then the resulting lack of understanding stems from your choice, I'm afraid. Now, commonly builders report on projects for many reasons: a) to get help if things go wrong b) to report particular changes which appear to be sonic improvements in case others want to consider or try them.This may not be any more significant than "I heard this, don't really know why" c) in motivational terms to get support and positive feedback from fellow enthusiasts for several hours at the drill press and soldering iron. This is completely reasonable. It is completely reasonable for people to ask for advice and information. However it is, in turn, completely reasonable for those who are invited to assist to point out what may be required in order for progress to be made. Without said info I can only speculate as to what *might* be occurring, but without relevant evidence, we can't get beyond that point. Slainte, Jim -- Electronics http://www.st-and.ac.uk/~www_pa/Scot...o/electron.htm Audio Misc http://www.st-and.demon.co.uk/AudioMisc/index.html Armstrong Audio http://www.st-and.demon.co.uk/Audio/armstrong.html Barbirolli Soc. http://www.st-and.demon.co.uk/JBSoc/JBSoc.html |
CD transports and resonance
In article , Tat Chan
wrote: Pooh Bear wrote: There's a lot of error correction capability on a CD. Hamming encoded IIRC. Forget how many bits of error it can correct transparently. Philips / Sony expected early CDs to have lots of errors so needed them to be correctable. Actually, CD uses a form of the Reed Solomon code. Though the Hamming code would provide error correction as well. Not sure of all the details, but yes IIRC it is a form of cross interleaved RS code. I think this is a 'block' code equivalent to a hamming code. However the channel bit stream is encoded on a number of levels between the sample data and the disc. Slainte, Jim -- Electronics http://www.st-and.ac.uk/~www_pa/Scot...o/electron.htm Audio Misc http://www.st-and.demon.co.uk/AudioMisc/index.html Armstrong Audio http://www.st-and.demon.co.uk/Audio/armstrong.html Barbirolli Soc. http://www.st-and.demon.co.uk/JBSoc/JBSoc.html |
CD transports and resonance
In article , Tat Chan
wrote: Rob wrote: Rob, getting the 'data off the disk' in a reliable manner is the only thing that matters in this context. If the output stream of 1s and 0s from an undamped and damped transport is exactly the same, then the damping doesn't make a difference. Slight quibble. The above assumes we can then convey the bitstream to the DAC with no unintended spurious effects. The most well-publicised version of this is 'jitter' in various forms. In principle this should not be a problem. In practice it probably is not a problem for most systems/disc. But it *might* be a problem in some cases where the player/disc/DAC arrangement is unusually poor for some reason. Slainte, Jim -- Electronics http://www.st-and.ac.uk/~www_pa/Scot...o/electron.htm Audio Misc http://www.st-and.demon.co.uk/AudioMisc/index.html Armstrong Audio http://www.st-and.demon.co.uk/Audio/armstrong.html Barbirolli Soc. http://www.st-and.demon.co.uk/JBSoc/JBSoc.html |
CD transports and resonance
John Phillips wrote:
In article , Ian Molton wrote: will you accept that two identical bitstreams will reproduce identically through a given DAC? It is not clear if this include timing as well as data. I assume both. However, for the sake of clarity if the jitter on the bitstreams were different and the DAC merely replicated the incoming clock on its D/A converter there could be an audible difference. Indeed, we've had a jitter thread before and the (predictable) conclusions we 1) a good dac is (to all reasonable limits) immune to all but the worst jitter 2) a source of even marginal quality will still have jitter far below audible limits even on a poor DAC 3) full reclocking is the only way to fully reconstruct the signal jitter free (to the limits of the reclocking units clock) |
CD transports and resonance
Rob wrote:
Well, it's one test but even it adds support to the 'vibration matters' Huh? Its a test in full-on-vibration conditions - have you ever heard a CDROM spin a disc for 50x thats such a poor quality disc it keeps slipping to 10x or less? hypothesis it wouldn't necessarily explain what's happening. The hypothesis (antithesis if you like) is that 'metal blocks strapped to CD ROMs affect sound'. It was suggested that 'metal blocks improve sound', actually. since not using metal blocks results in perfect extraction, I dont think theres any validity to the theory. I can think of tempertaure, media - I don't know, gravity, magnetism, radiation! gravity?! are you suggesting the difference in gravitational field over 2 inches height of the player will even be detectable?! or did you mean andy should drop the player? radiation is also damn unlikely, given andy appears to still be alive and cacner free... I just have no idea. My problem with this is a reaction to the absolute dogma of positivist approaches: 'if it measures, it's real'. Im certainly willing to accept a weird hypothesis, but if any wants some credibility he will have to *at least* perform the most basic tests of all - not techinical tests at all, but the psychological bare minimum to establish the effect is real. I have absoltely no technical understanding of the issue. I've read a few articles and follow Jim Lesurf's contributions with interest. JL is probably the most qualified to explain things from the technical/quantitative/positivist viewpoints - and you will note his reply in this context is slightly equivocal - there is 'wiggle room' Indeed - Jim has graciously allowed andy to admit defeat by saying the effect is due to noise from the player and nothing to do with digital adio at all. I note Andy still hasnt bitten though... - and, IIRC, he is/has been a user of dedicated transports, although this may have been to do with DACs, can't remember. Actually hes said over and over that one of his players is using a standard PC transport and sounds no different. Just one thing - would your test show jitter? No, it wouldnt, however if jitter was great enough to be audible then either his DAC or transport, or both, would be broken. |
CD transports and resonance
Tat Chan wrote: Pooh Bear wrote: There's a lot of error correction capability on a CD. Hamming encoded IIRC. Forget how many bits of error it can correct transparently. Philips / Sony expected early CDs to have lots of errors so needed them to be correctable. Actually, CD uses a form of the Reed Solomon code. Though the Hamming code would provide error correction as well. Thanks for refreshing my memory on that point. Graham ;-) |
CD transports and resonance
In article ,
Dodge McRodgered wrote: Even if that's the case, you accept that Andy "hears" what he says he can hear? No. All I'm prepared to accept is that he *thinks* he can hear a difference. The other alternative doesn't bear thinking about. ;-) -- *Not all men are annoying. Some are dead. Dave Plowman London SW To e-mail, change noise into sound. |
CD transports and resonance
I think this has been a useful thread for raising some of the issues about
measurement and non measurement. Just to go over this ground again, we know that this ng is used both by those with measuring equipment and those without. At the moment I'm without - not by choice particularly, I just haven't made time to learn how to use my scope. I'm far from against measurement, and indeed I take my gear round, once finished, to a friends to have it measured by quite sophisticated equipment. Anyway, the point I'm making is that there are those on this ng without access to measuring equipment and they have as much right to make comments about their systems using the measuring equipment they do have, which is their ears. In return the engineers needing measured data are quite entitled to dismiss the results as unproven. I have no difficulty with that. But this is not the whole story. Let us now take the case of a person who makes a statement on the ng "I hear phenomenon A". If the response is "If you don't have mesurements to prove it I won't believe it", then that's fine. But that frequently isn't the response. If the response is "If you can't measure it you should not have made that statement". Since we know in advance that there are those on the ng wthout measuring equipment, to imply that they should not have made a statement without measured data would be effectively to gag them. They have as much right to make observations as the next man, so I would regard gagging ng members as wholly unacceptable, even elitist. And if in the same post we have "the poster should abide by the Scientific Method" and "the poster is an idiot", we know that posters are not idiots so we must further level the charge of hypocrasy to add to elitism. To recap these points: 1) this ng is for those who measure with equipment and who measure with their ears 2) anybody has the right to disbelieve anything 3) to imply that somebody without measuring equipment should not post opinions that can't be measured is elitist 4) to simultaneously ask for scientific methods and make fundamental mistakes in measuring the intelligence of others is hypoctitical. === Andy Evans === Visit our Website:- http://www.artsandmedia.com Audio, music and health pages and interesting links. |
CD transports and resonance
On 08 Nov 2004 09:20:43 GMT, ohawker (Andy
Evans) wrote: I think this has been a useful thread for raising some of the issues about measurement and non measurement. Just to go over this ground again, we know that this ng is used both by those with measuring equipment and those without. At the moment I'm without - not by choice particularly, I just haven't made time to learn how to use my scope. I'm far from against measurement, and indeed I take my gear round, once finished, to a friends to have it measured by quite sophisticated equipment. Anyway, the point I'm making is that there are those on this ng without access to measuring equipment and they have as much right to make comments about their systems using the measuring equipment they do have, which is their ears. In return the engineers needing measured data are quite entitled to dismiss the results as unproven. I have no difficulty with that. But this is not the whole story. Let us now take the case of a person who makes a statement on the ng "I hear phenomenon A". If the response is "If you don't have mesurements to prove it I won't believe it", then that's fine. But that frequently isn't the response. If the response is "If you can't measure it you should not have made that statement". Since we know in advance that there are those on the ng wthout measuring equipment, to imply that they should not have made a statement without measured data would be effectively to gag them. They have as much right to make observations as the next man, so I would regard gagging ng members as wholly unacceptable, even elitist. And if in the same post we have "the poster should abide by the Scientific Method" and "the poster is an idiot", we know that posters are not idiots so we must further level the charge of hypocrasy to add to elitism. To recap these points: 1) this ng is for those who measure with equipment and who measure with their ears 2) anybody has the right to disbelieve anything 3) to imply that somebody without measuring equipment should not post opinions that can't be measured is elitist 4) to simultaneously ask for scientific methods and make fundamental mistakes in measuring the intelligence of others is hypoctitical. === Andy Evans === Visit our Website:- http://www.artsandmedia.com Audio, music and health pages and interesting links. Andy, why do you misrepresent what we have been saying. Certainly in respect to your resonance damping claims we have said precisely what you say here - *use your ears*. This doesn't require any special equipment whatever - all it needs is for you to listen to your equipment, not look and listen. There is no hypocrisy here, and those of us who are saying it are notably those who understand the balance between measuring and listening, particularly the ways in which they support each other in the design of hi fi equipment. If you are a designer you do actually need both at all stages of the design process. And it is the fact that we understand how various bits of the system work, and what factors can have which effects that allows us to dismiss so readily your claims regarding CD resonance. When we ask you to do the real *listening* tests, it is not in expectation that you will come back here with some wonderful new scientific principle that we were unaware of, but in the hope that you can move your understanding on a bit. Patronising? I hope you don't see it that way. So to answer your points as you raise them 1. Most emphatically no. Listen any way you like, and post whatever opinions you like, but if you announce the discovery of some effect that the rest of us believe to be impossible - be prepared to defend it, not moan about being challenged. 2. Not sure what you mean by having the right. Believe or disbelieve what you like - it is not a question of rights. But if you make an assertion, be prepared to offer a defence of your position. 3. Post whatever opinions you like - nobody is worried. Post an assertion that you have discovered a new effect, and you must be prepared to defend your claim. 4. Just do what you know to be right. You have training in psychology, and it shouldn't be necessary to explain this to you. Is it not fair to call somebody who wilfully fails to follow a method he knows to be the only one that yields a true result unintelligent? d Pearce Consulting http://www.pearce.uk.com |
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