vas@pavepaws.UUCP (07/18/86)
(dummy line) (1) As far as I know, in-dash CD players are all of the insert-disk-through-the-slot variety. I hesitate to purchase on of these since i fear the CD is vulnerable to scratching as it is pushed through the flap on the slot. I am hoping that someone out there can put to rest these fears so that I can listen to crystal clear high fidelity in my soon-to-be-purchased-to-go-with-the-CDplayer car. (2) I understand that, when playing a VERY scratched disk, the single beam CD players put out less noise and fewer errors than three beam players. I was given a demonstration to this fact(?) at a stereo shop: the salesperson brought forth a store demo disk with a significant amount of scratches from being thrown across the salesfloor (to demonstrate it's durability to previous customers) and stepped on. He played it on a brand-x three beam machine and the noise and errors where definately audible. He then proceeded to give the disk a run on a single beam Sony (he said all Sony machines are single beam due to this advantage) and the noise was either inaudible or significantly less than the aforementioned three beam machine. Any comments on why this is so, IF this is so at all? srinivas sudanagunta vas@pavepaws.berkeley.edu vas. ucbvax!pavepaws!vas
sjc@mips.UUCP (07/21/86)
> I understand that, when playing a VERY scratched disk, the single beam > CD players put out less noise and fewer errors than three beam players. > > I was given a demonstration to this fact(?) at a stereo shop: the > salesperson brought forth a store demo disk with a significant amount > of scratches... > > He played it on a brand-x three beam machine and the noise and > errors where definately audible. He then proceeded to give the disk a > run on a single beam Sony (he said all Sony machines are single beam > due to this advantage) and the noise was either inaudible or > significantly less than the aforementioned three beam machine. Whether he realized it or not, your salesperson was performing a scientific experiment, constraining one variable (the demo disk) and allowing another (the CD player) to vary. I conclude from the results that Sony does a better job than BrandX with this disk. He concludes that all one-beam players do a better job than all three-beam players on all damaged disks. Does he know that the difference between Sony and BrandX is due solely to the number of beams, and not to differences in the error correction algorithms in their ICs, or in their servomechanisms? Does he know that this damaged disk is representative of all defective disks (some with scratched surfaces, and others with pressing defects below the surface? For what it's worth, my experience with (admittedly only) a handful of defective disks and a handful of players is that often one disk will suggest player A is better than player B, and another disk will suggest the opposite. I'm glad to see that the one-beam people are fighting back against the three-beam people, however. For a time, I thought the advertising copywriters were about to establish the superiority of three beams based merely on the well-known fact that three is a larger number than one. -- ...decwrl!mips!sjc Steve Correll