I would like to test the audibility of illuminating a CD with a coloured led as many people claim that this can make a noticeable difference. What I propose is to construct a counter which displays a number which can be incremented and which controls the status of the LED in pseudorandom manner ( the exact details of the device are unimportant at the moment ). The test would be run as follows.
The counter would be reset to 1, the cd played and the status of the led would be determined by the quality of the replay and noted down. The counter would then be incremented by one a new LED status would be produced and the CD or an other CD or track played and again the quality again noted. This would be repeated a considerable number of times at the end of which would be a list of numbers and corresponding list of LED status determined by listening, this would then be compared to a list of the actual led status from which it should be possible to determine the significance of the LED on the reproduced sound. Is this a reasonable protocol to determine the audibility of the LED
Stuart
The counter would be reset to 1, the cd played and the status of the led would be determined by the quality of the replay and noted down. The counter would then be incremented by one a new LED status would be produced and the CD or an other CD or track played and again the quality again noted. This would be repeated a considerable number of times at the end of which would be a list of numbers and corresponding list of LED status determined by listening, this would then be compared to a list of the actual led status from which it should be possible to determine the significance of the LED on the reproduced sound. Is this a reasonable protocol to determine the audibility of the LED
Stuart
Hi Stuart,
I like your style!! I'm considering the LED mod myself.
Verifying subjective results is a contentious issue around here but I think you've got the right idea.
I will certainly be very interested in your results.
The truth for me is that I will probably hear a difference if I do the mod but don't trust my own mind. Past experience has taught me that the improvement I hear is often directly proportional to the effort and enthusiasm I use.
Will you be testing with different colours?
Cheers,
Martin.
I like your style!! I'm considering the LED mod myself.
Verifying subjective results is a contentious issue around here but I think you've got the right idea.
I will certainly be very interested in your results.
The truth for me is that I will probably hear a difference if I do the mod but don't trust my own mind. Past experience has taught me that the improvement I hear is often directly proportional to the effort and enthusiasm I use.
Will you be testing with different colours?
Cheers,
Martin.
It is a good idea to try to test this claim, however, no matter how well thought out your protocol, the "believers" will ultimately find something wrong with the methodology, unless of course, it validates their claims, in which case no one can make any argument against your test methodology.
Now for the technical stuff... I think your idea is good, but you need to be able to find out after-the-fact whether the LED was on or not during a praticular listening interval. If you use a pseudo random sequencer to turn the LED on or off, you can reproduce the LED sequence any time and check it after-the-fact by entering the same seed value. This could be managed by a simple microcontroller program.
If you manage to hear a difference or not, questions will arise as to how much light you used, how was it distributed in the CD drawer, and was there any possibility of the current through the LED(s) causing some audible effect. If you use a high power LED, there may also be issues of how the heat generated by the LED was removed from the CD drawer.
I think to be safe, some sort of light pipe or fiber optic coupling should be used so that the LED and it's current source can be loacted well away from the CD player, or at least the CD drawer.
Will the intervals also be of random length or will they be equally long? Will the listener know when the interval has elapsed of will he/she simply be listening and recording his/her impression at regular intervals? For example, if the LED on/off intervals are random between 2 and 3 minutes, have the listener mark his/her impression every 10 seconds, and don't allow them to know the beginning or end of a LED on/off interval.
Obviously, the CD player should be located out of sight of the listener lest the LED status be visible to them.
Finally, without a human to verify that the LED is actually on or off during any given interval, you'll run afoul of the "if a tree falls in the forest and there's no one there to hear it, does it make any sound?" college philosophy drop-outs. You just can't educate some people...
I_F
Now for the technical stuff... I think your idea is good, but you need to be able to find out after-the-fact whether the LED was on or not during a praticular listening interval. If you use a pseudo random sequencer to turn the LED on or off, you can reproduce the LED sequence any time and check it after-the-fact by entering the same seed value. This could be managed by a simple microcontroller program.
If you manage to hear a difference or not, questions will arise as to how much light you used, how was it distributed in the CD drawer, and was there any possibility of the current through the LED(s) causing some audible effect. If you use a high power LED, there may also be issues of how the heat generated by the LED was removed from the CD drawer.
I think to be safe, some sort of light pipe or fiber optic coupling should be used so that the LED and it's current source can be loacted well away from the CD player, or at least the CD drawer.
Will the intervals also be of random length or will they be equally long? Will the listener know when the interval has elapsed of will he/she simply be listening and recording his/her impression at regular intervals? For example, if the LED on/off intervals are random between 2 and 3 minutes, have the listener mark his/her impression every 10 seconds, and don't allow them to know the beginning or end of a LED on/off interval.
Obviously, the CD player should be located out of sight of the listener lest the LED status be visible to them.
Finally, without a human to verify that the LED is actually on or off during any given interval, you'll run afoul of the "if a tree falls in the forest and there's no one there to hear it, does it make any sound?" college philosophy drop-outs. You just can't educate some people...
I_F
I twice ripped a track from the same CD with EAC. First with a closed CDRom drive, second with the drive opened. I put a strong lamp on top (not a colored LED) of the drive to illuminate the CD.
I compared the two waveforms with Audition. There is not a single bit of difference between both rips.
Let me know if I didn’t understand the purpose of this thread since I don’t want to spoil the fun.
/Hugo
I compared the two waveforms with Audition. There is not a single bit of difference between both rips.
Let me know if I didn’t understand the purpose of this thread since I don’t want to spoil the fun.
/Hugo
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Come on guys give it a chance, that sort of unhealth sceptism isn't helpful. Netlist first of all your methodology is wrong, one like you said you didn't use a blue or green LED and secondly EAC corrects for errors in the reading, what I'd be looking for is how much it tries to correct them during the extraction process.
I was wondering if it could be as simple as to be nothing to do with changes in the reading characteristics but becuase the you're biasing the photo diode you might not cause as much voltage swing for other circuitry.
I was wondering if it could be as simple as to be nothing to do with changes in the reading characteristics but becuase the you're biasing the photo diode you might not cause as much voltage swing for other circuitry.
A lot of CDROM drives can report errors to the controller. You might be able to find software to tell you how many errors occurred during a rip.
Of course, error correction on CDs works well, so it seems unlikely that anything that happens during the reading fo the CD is going to improve on that. When a CD can't correct the error it interpolates. When enough samples are missing that it can't interpolate, nost CD players mute the output. That's a pretty rare occurance in my experience.
The only thing the light could possibly do is improve the already miniscule error rate, so why bother? I suspect it's is a marketing gimmick.
I_F
Of course, error correction on CDs works well, so it seems unlikely that anything that happens during the reading fo the CD is going to improve on that. When a CD can't correct the error it interpolates. When enough samples are missing that it can't interpolate, nost CD players mute the output. That's a pretty rare occurance in my experience.
The only thing the light could possibly do is improve the already miniscule error rate, so why bother? I suspect it's is a marketing gimmick.
I_F
Hi, sorry, realy, it was just a joke.
If I undertood the article correct, in layman's terms, it is like ligthing a candle in a room you need to search with a torch, it will help you see things better... allthough a lazer is a pretty bright torch, isn't it?
Can you say playstation 1 mod? If it works, it should turn these into beasts.
If I undertood the article correct, in layman's terms, it is like ligthing a candle in a room you need to search with a torch, it will help you see things better... allthough a lazer is a pretty bright torch, isn't it?
Can you say playstation 1 mod? If it works, it should turn these into beasts.
I am going to blue & green LED's on my Plextor 716AL,Plextools pro can read C1 & C2 & jitter errors.Having tried various disc several times the results are repeatable and consistant. Maybe this will show if the disc is influenced by an LED.
If Plextor are to be credible they once claimed their drive bays were black, for burn acurracy and prevents laser reflections.
Anyone with a Liteon drive can use KProbe which is free and offers some functions to Plextools pro, that is not free and only works on Plextor drives.Plextor drives also have VariRec that alters the laser power, this is claimed to alter sound of audio CD's never tried it myself.
KProbe
http://club.cdfreaks.com/showthread.php?s=&threadid=93944
If Plextor are to be credible they once claimed their drive bays were black, for burn acurracy and prevents laser reflections.
Anyone with a Liteon drive can use KProbe which is free and offers some functions to Plextools pro, that is not free and only works on Plextor drives.Plextor drives also have VariRec that alters the laser power, this is claimed to alter sound of audio CD's never tried it myself.
KProbe
http://club.cdfreaks.com/showthread.php?s=&threadid=93944
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