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#1
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We passed the DBT.
After reading many postings about our human ears limitation to hear the
difference between equipments above certain level and our current player specs were more enough, five of us decided to do our own DBT and see if we can tell the difference. Three players were used and specs given were taken from the manuals:- Player A with the following specs:- (Price about $500 ) S/N ratio = 115db Harmonic distortion = 0.003% Dynamic Range = 99db Frequency Response = 2hz - 20Khz (+-0.5db). jitter = not given but I think it is few hundred ps. Player B (Classe Audio CDP-10) :- Frequency Response = DC- 20Khz (+-0.1db). S/N ratio = 100db typical? ( Iexpected it to be higher) THD + noise= 0.00003 (wow! it means good right?) Dynamic Range = 16 bit linear (I don't what that is but is it something like 98db?) jitter = 2 ps (wow, again) Results 4 of us unanimously agreed that Player B sounded better when compared with player A. I am not included because i was doing the switching. But something interesting happened. After they take a short break in the garden (while I am supposed to switch to Player C), they were asked to identify which player was playing when they walked in. They have to tell whether it was C or not. In another word, have they heard the sound of the player or not, since they do not which is player A or B or C. Point to note: 1.They have not heard C yet. Player A was playing and they were mislead to decide between Player B and C. 2 When I say Player A or B they do not know which is which. (They would say this sound is better than the earlier one. In a way I can play the same player over and over again deceiving them to think I am testing multiple players) The result was not encourging and I would say all them were guessing. they can't tell for sure which player was playing. Then I switched to CDP-10 (player B), they all agreed "this player" is more pleasant but they do not know if that was player A or B or even C. In the end, Player C was not tested. between Player A and B, B won. So far, according many in RAHE, the specs above is quite insignificant to make audible difference but yet 4 of us correcly identified Player B as superior to player A. So guys how you want to explain this and what else I should do to make the test more reliable. Cheers. |
#2
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We passed the DBT.
Chelvam wrote:
After reading many postings about our human ears limitation to hear the difference between equipments above certain level and our current player specs were more enough, five of us decided to do our own DBT and see if we can tell the difference. Three players were used and specs given were taken from the manuals:- Player A with the following specs:- (Price about $500 ) S/N ratio = 115db Harmonic distortion = 0.003% Dynamic Range = 99db Frequency Response = 2hz - 20Khz (+-0.5db). jitter = not given but I think it is few hundred ps. Player B (Classe Audio CDP-10) :- Frequency Response = DC- 20Khz (+-0.1db). S/N ratio = 100db typical? ( Iexpected it to be higher) THD + noise= 0.00003 (wow! it means good right?) Have you missed the precentage sign? Dynamic Range = 16 bit linear (I don't what that is but is it something like 98db?) jitter = 2 ps (wow, again) Results 4 of us unanimously agreed that Player B sounded better when compared with player A. Blind or sighted? I am not included because i was doing the switching. But something interesting happened. After they take a short break in the garden (while I am supposed to switch to Player C), they were asked to identify which player was playing when they walked in. They have to tell whether it was C or not. In another word, have they heard the sound of the player or not, since they do not which is player A or B or C. Point to note: 1.They have not heard C yet. Player A was playing and they were mislead to decide between Player B and C. 2 When I say Player A or B they do not know which is which. (They would say this sound is better than the earlier one. In a way I can play the same player over and over again deceiving them to think I am testing multiple players) The result was not encourging and I would say all them were guessing. they can't tell for sure which player was playing. Then I switched to CDP-10 (player B), they all agreed "this player" is more pleasant but they do not know if that was player A or B or even C. In the end, Player C was not tested. between Player A and B, B won. So far, according many in RAHE, the specs above is quite insignificant to make audible difference but yet 4 of us correcly identified Player B as superior to player A. So guys how you want to explain this and what else I should do to make the test more reliable. Cheers. One extremely important point: you have to carefully match the playback levels. To 0.1 dB (within 1%). Your results are meaningless if the levels are not matched. |
#3
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We passed the DBT.
On 26 Jun 2004 14:32:23 GMT, "Chelvam" wrote:
After reading many postings about our human ears limitation to hear the difference between equipments above certain level and our current player specs were more enough, five of us decided to do our own DBT and see if we can tell the difference. Three players were used and specs given were taken from the manuals:- Player A with the following specs:- (Price about $500 ) S/N ratio = 115db Harmonic distortion = 0.003% Dynamic Range = 99db Frequency Response = 2hz - 20Khz (+-0.5db). jitter = not given but I think it is few hundred ps. Player B (Classe Audio CDP-10) :- Frequency Response = DC- 20Khz (+-0.1db). S/N ratio = 100db typical? ( Iexpected it to be higher) THD + noise= 0.00003 (wow! it means good right?) Dynamic Range = 16 bit linear (I don't what that is but is it something like 98db?) jitter = 2 ps (wow, again) Results 4 of us unanimously agreed that Player B sounded better when compared with player A. I am not included because i was doing the switching. But something interesting happened. After they take a short break in the garden (while I am supposed to switch to Player C), they were asked to identify which player was playing when they walked in. They have to tell whether it was C or not. In another word, have they heard the sound of the player or not, since they do not which is player A or B or C. Point to note: 1.They have not heard C yet. Player A was playing and they were mislead to decide between Player B and C. 2 When I say Player A or B they do not know which is which. (They would say this sound is better than the earlier one. In a way I can play the same player over and over again deceiving them to think I am testing multiple players) The result was not encourging and I would say all them were guessing. they can't tell for sure which player was playing. Then I switched to CDP-10 (player B), they all agreed "this player" is more pleasant but they do not know if that was player A or B or even C. In the end, Player C was not tested. between Player A and B, B won. So far, according many in RAHE, the specs above is quite insignificant to make audible difference but yet 4 of us correcly identified Player B as superior to player A. So guys how you want to explain this and what else I should do to make the test more reliable. Cheers. I don't actually follow the protocol of the trial. Could you describe it please? d Pearce Consulting http://www.pearce.uk.com |
#4
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We passed the DBT.
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#5
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We passed the DBT.
On 6/26/04 7:14 PM, in article trnDc.101928$Hg2.29121@attbi_s04, "Nousaine"
wrote: 4 of us unanimously agreed that Player B sounded better when compared with player A. I am not included because i was doing the switching. But something interesting happened. How were decisions recorded? Were decisions of each participant made in private? It sounds as though conditions were 'open-session' It is important for us as a group to keep *our* biases under control. As someone who has said that all CD players sound the same - you seem to be searching for an answer that will confirm your apparent bias. I would caution you against this. |
#6
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We passed the DBT.
"Chelvam" wrote in
: After reading many postings about our human ears limitation to hear the difference between equipments above certain level and our current player specs were more enough, five of us decided to do our own DBT and see if we can tell the difference. Three players were used and specs given were taken from the manuals:- Player A with the following specs:- (Price about $500 ) S/N ratio = 115db Harmonic distortion = 0.003% Dynamic Range = 99db Frequency Response = 2hz - 20Khz (+-0.5db). jitter = not given but I think it is few hundred ps. Player B (Classe Audio CDP-10) :- Frequency Response = DC- 20Khz (+-0.1db). S/N ratio = 100db typical? ( Iexpected it to be higher) THD + noise= 0.00003 (wow! it means good right?) Dynamic Range = 16 bit linear (I don't what that is but is it something like 98db?) jitter = 2 ps (wow, again) Results 4 of us unanimously agreed that Player B sounded better when compared with player A. I am not included because i was doing the switching. But something interesting happened. After they take a short break in the garden (while I am supposed to switch to Player C), they were asked to identify which player was playing when they walked in. They have to tell whether it was C or not. In another word, have they heard the sound of the player or not, since they do not which is player A or B or C. Point to note: 1.They have not heard C yet. Player A was playing and they were mislead to decide between Player B and C. 2 When I say Player A or B they do not know which is which. (They would say this sound is better than the earlier one. In a way I can play the same player over and over again deceiving them to think I am testing multiple players) The result was not encourging and I would say all them were guessing. they can't tell for sure which player was playing. Then I switched to CDP-10 (player B), they all agreed "this player" is more pleasant but they do not know if that was player A or B or even C. In the end, Player C was not tested. between Player A and B, B won. So far, according many in RAHE, the specs above is quite insignificant to make audible difference but yet 4 of us correcly identified Player B as superior to player A. So guys how you want to explain this and what else I should do to make the test more reliable. Cheers. The audibility test is a nice first step, but what precise measurement could be made to explain the difference? What is the cause of the better sound of the unit in question? Frequence response, etc. are all nice things to measure, but there are many other things to measure. Of course, there is also the issue of D-A converter used, D-A scheme, op- amps, grade of each, etc. There may be too many variables to take in at once. r -- Nothing beats the bandwidth of a station wagon filled with DLT tapes. |
#7
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We passed the DBT.
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#8
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We passed the DBT.
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#9
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We passed the DBT.
"Bromo" wrote in message
news:8VnDc.186683$Ly.95137@attbi_s01... On 6/26/04 7:14 PM, in article trnDc.101928$Hg2.29121@attbi_s04, "Nousaine" wrote: 4 of us unanimously agreed that Player B sounded better when compared with player A. I am not included because i was doing the switching. But something interesting happened. How were decisions recorded? Were decisions of each participant made in private? It sounds as though conditions were 'open-session' It is important for us as a group to keep *our* biases under control. As someone who has said that all CD players sound the same - you seem to be searching for an answer that will confirm your apparent bias. I would caution you against this. Actually all these about audible inaudible, 0.01%, jitter and other scientific measurements, me wonder would Aliens think that the difference between human and Chimpanze cannot be perceived due to the similarities of genomic sequence is to be 98.7% alikeness. |
#11
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We passed the DBT.
On 6/27/04 4:02 PM, in article OJFDc.190029$Ly.4456@attbi_s01, "Nousaine"
wrote: Would you blame me for caution? Nope not at all - but with such an array of experience, it is possible to get jaded as well - which was my real caution! :-) |
#12
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We passed the DBT.
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#13
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We passed the DBT.
Nousaine wrote:
"Bob Marcus" wrote: Here's what I would do next. You "know" that everybody prefers B to A. So do a longer test; have each subject do 5 trials, mixing up A and B randomly so they don't know which is which each time. This will give you 20 trials. If they agree on B (or A!) at least 15 times out of 20, I'd say there's an audible difference between them. But: 1) You must level-match to within 0.1 dB. 2) You should get someone other than yourself to do the random switching of A and B, and keep that person away from the subjects. 3) You must make sure each subject is making his preference on his own, without consulting the others. Good luck. bob Another issue with cd players is synch-ing of playback start-time. In an identification test (e.g., ABX), absolutely, because if A and B are out of synch it will be easy to tell which one X is in synch with. That's why ABX tests of disk players are difficult for amateurs to pull off. But what this fellow was doing was an A-B preference test. If you're just choosing which of two alternatives you prefer, I would think that time-synching wouldn't be as critical. You don't want the same one leading every time, but just stopping and starting the players between each trial might be enough to randomize this. If not, you could intentionally randomize which player is leading each time. bob __________________________________________________ _______________ FREE pop-up blocking with the new MSN Toolbar – get it now! http://toolbar.msn.click-url.com/go/...ave/direct/01/ |
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