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In Reply to: RE: If this were for some odd reason true... then it makes no sense posted by Enchantment1.6s on December 09, 2009 at 12:58:19
=> then the instant that CD touches the disc tray the plastic of the tray would change the sound.
this is indeed very true. i am glad you have read my posts carefully and have given thoughts to the implications that come after.
i have actually done some prelimary test with different CD player trays from different players. it involves first "dis-infecting" a disc, to remove or to minimise the residual effects of coming into contact with cd jewel cases. a simple way is to lay the cd disc on a flat anti-static material. both sides of the disc are laid on the material for a short period, taking care not to shift the disc in anyway while it is laid on the anti-static material - just in case the movement (rubbing against the surface of the material) generate unwanted other sonic artifacts.
a very effective anti-static material that i have used is the "black panther cloth" used by photographers to wipe clean camera lenses to minimise dust attraction.
See link here:
http://kinetronics.com/store/panther.html
the "dis-infected" disc is then placed on the disc tray of another player (SCD-XA9000ES with plastic tray, and a Yamaha model with rubber on the tray) before being played in the main player being used for testing (in the case, a Sony SCD-1). i also repeated the whole procedure with the disc first being "dis-infected", then placed on other materials like aluminium (top-panel of pass lab X2.5), dark arcylic (gyro se turntable platter) before being played through the SCD-1. these 4 materials were compared to direct playback on SCD-1 immediately after "dis-infecting". No surprises. they all have different effect on the sound of the disc. the surprising thing actually is that when the disc is being played on the SCD-1, the sonic changes that came from touching all the 3 different materials earlier is still audible. having said that i am sure that the cd disc would probably have gained some other sonic artifacts when it was being loaded on the SCD-1, since this process involves loading a heavy stabilizer on top of the disc. although there is a layer of felt underneath the stabilizer that prevents actual contact with the metal material, it is difficult to eliminate this last stage of "contamination". but still, touching the earlier materials, the sonic changes in the disc is still audible played through my scd-1. the aluminium top panel induce a thin bright sound, with forward imaging. the dark arcylic patter also cause a bright sound, but the soundstaging is more open, and imaging more recessed.
i also tried this test in a Hifi store. the main player being used for testing was a sony CDP-XA50ES. no "dis-infecting" was done prior, we just played the disc straight away after resting it in turn, on the transparent platter of the clearaudio turntable, and on the graphite platter of the simon yoke. the clearaudio platter gave a dull and closed-in sound, while the simon yoke gave it a hard and bright sound. interestingly, the platters of the gyro se and clearaudio are both made of arcylic, but their effects on cd discs are opposites of one another.
other implication from all of this?
besides CD discs sounding the way they do because of their jewel cases, some CD players may sound the way they do - because of the materials used in their disc trays?
anti-static laced disc trays, anyone?
Follow Ups:
Static charges on a disk seems like a plausible source of problems, I've messed around a bit in this area a couple of years ago but haven't gotten back to it.
But I don't understand how the problem can "hang" in your system and even affect other sources as you mentioned above. That is the thing that makes me think you are pulling our legs. Or maybe it's a mixture of the two.
Anyway I built an electrosope by taping a dog hair to a toothpick and it's sensitive enough to get a decent idea of the charge distributions on the disk and their relative levels. I then ordered an ultra-high input impedance op-amp eval board to make an accurate electroscope but I need to get some teflon triax for it and never finished. The neat thing about the dog hair version is that I could just pluck the active element off my shirt and had it running in less than three minutes. If your trays are affecting the residual charge distribution significantly you will probably be able to see it with the dog hair scheme. If you don't have a dog, I'd be delighted to send you as many hairs as you wish, I'm long on them...
Rick
PS: Please animal lovers, I didn't try anything else so don't give me any static. For all I know human, gerbil or cat hair works just as well or better.
yes. static charges added onto discs do sound plausible.
however, i don’t believe transparent cases are removing static – they are probably still adding static, but of a different type instead.
here's a test you can try easily (for a healthy system unlike mine):
wrap your CD in common kitchen aluminium foil. there are usually 2 sides to aluminum foil - 1 shinny side and 1 matt (non glossy) side. take turn to wrap each side over the same CD and play it. the shinny side will create a bright thinny sound, while the matt side will create a very dull sound. both sides are adding static. but the static condition they created onto the disc is opposite to one and the other.
so if we assume the black colour case is adding some static charge, while it cause my system's imaging to skew towards the left (always the left), it also impart a mellow, bloated sonic signature to the sound as well. i notice, over some time, some of this sonc signature get attenuated the longer the disc is being played.
when the same disc has touched a transparent case, and then played through my system, not only does it kick centre-fill imaging back to centre position again, it also imparts another sonic signature - something brighter, a more open and recessed soundstage. some low level details like piano pedals and intake of breath become more audible. but this change is not "stable". overtime, the sonic signature and the size of the soundstage get attenuated, the longer the disc is being played. but all the while the center-fill imaging remains stable in the center.
if the dark grey cases are adding static, then it stands to reason that the transparent cases are adding static too - albiet of the opposite type. So when this opposite-static-charged disc is played in my system, it restores equilibrium to my system previously infected with static in the other direction.
now i believe when the audio system has a neutral static condition – a balance containing either types – then imaging can be properly projected.
makes sense?
now take this further - if an audio system is not afflicted by any adversed static condition - then sound can be further improved?
this will be a subject of future posts.
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