On 03/07/14 14:35, Anton Aylward wrote:
On 07/03/2014 09:02 AM, michael norman wrote:
Laser pickups were available in the 70's they didn't work.
Sort of, depending on your definitions of those various terms.
IIR B+O had a series of players that had a true parallel tracking arm, that unlike the radial arms did not need the _varying_ angular pressure to move the arm inwards as it followed the spiral of the groove. Again IIR Sony, Technics and an American firm also tried this, but without the brand image of B+O.
This pressure was very faint and a well engineered, properly balanced and set up tracking arm did not apply enough pressure to damage the groove. But the point is that as the arm pivoted the pressure changed so the 'wear' on the vinyl was no even.
IIR correctly B+O then went one step further and used a pair of lasers at an angle to track the groove and a motor to do the arm movement. The next logical step would have been to shine lasers to follow the sides of the groove and eliminate the 'needle'. I don't know if they ever took that step.
However I do recall reading about a box that looked like the player for video disks (which were read by lasers). I think it was from a Japanese company.
Ah, here we are, google is great http://www.theabsolutesound.com/articles/elp-lt-1lrc-laser-turntable/ Well that review sounds like the old argument about valve amplifiers vs transistors. And the reviewer was ignorant of the ability of software to clean up all manner of poor signals.
This http://www.stereotimes.com/turn030300.shtml seems better informed.
Software can deal with eliminating the 'pop' noise that comes from microscopic dust in the groove and even from cracks. But wear rounds off the groove and the high frequencies get lost. There is a lot of very good software for cleaning up audio, thanks to the Cold War and the NSA.
For my purposes I don't particularly want software however good it might be to clean up anything, unless it really needs to do so. I am reminded of the CEDAR process applied in the early days on cds. If my memory served it wasn't very good
While this is relevant to thee and mee and our sampling of those pieces ov vinyl that never made it to CD, much of the mainstream of 'old' music on CD comes from the master tapes and not from replaying vinyl.
Would that that were so but it isn't. Tape degrades, original tape masters can be very hard to find for all sorts of reasons. Responsible people who reissue stuff do it from the best masters they can find, and if they are honest will freely share what they used. There is no standard definition for where a master comes from, for example some companies advertise their product as "from the master tape" without specifying what the origin of that tape might be. It could well be a second or third generation copy used in another country to press an lp or cd. This is not conspiracy theory, I could point you to some links dealing with all this, but isn't this all off topic ?
Mike
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