Laser turntable

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A laser turntable is a phonograph that plays gramophone records using a laser beam as the pickup, rather than a conventional diamond tipped stylus. This playback system has the unique mechanical advantage of never physically touching the record during playback; instead, a focused beam of light traces the signal undulations in the vinyl, with zero friction, zero mass and zero record wear. Vinyl LP's played with a laser playback system can theoretically "last forever", as there is no deterioration caused by passing a stylus through the groves.

Current laser turntables can play most varieties of phonograph records (45s, 33.3 LPs, or 78s), and play them with high fidelity. Being quite expensive, they are favored by record libraries and radio stations (for archival use and transcription to digital media) and by audiophiles with extensive personal record collections.

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[edit] History

The laser turntable was first conceived by Robert S. Reis, a graduate student at Stanford University (his Master's thesis was "An Optical Turntable"). In 1983 Reis and fellow Stanford engineer Robert E. Stoddard founded Finial Technology with $7 million in venture capital. A year later servo-control expert Robert N. Stark joined the effort. A non-functioning mock-up of the optical turntable was shown at the 1984 Consumer Electronics Show (CES), generating much interest and a fair amount of mystery, since the patents had not yet been granted and the details had to be kept secret. The first working model, the Finial LT-1, was completed two years later and presented at the 1986 CES. The prototype had an interesting flaw: it was so accurate that it played every particle of dirt and dust on the record, rather than pushing them aside as a conventional stylus would. The projected $2500 street price (raised to $3786 in 1988) limited the potential market to serious well-heeled audiophiles.

Unfortunately for Finial, its laser turntable development coincided with the introduction of the Digital Compact Disc, which began flooding the market at prices comparable to LPs (with CD players in the $300 range). Vinyl record sales plummeted, and many turntable manufacturers failed as a result.

Although millions of LP collectors all over the world could benefit from a frictionless and wearless high-fidelity playback device, the Finial turntable never went into mass production. Tooling delays, component unavailability (in the days before cheap lasers), marketing blunders, and high development costs prevented it. With over US$20 million in venture capital invested, Finial was faced with a Hobson's choice: a selling price that was out-of-range for most consumers; or gamble on going into mass production (thus lowering the selling price) at the very moment the bottom was dropping out of the market (not to mention a simultaneous recession). In late 1989, Finial's investors finally succumbed to their bad timing and liquidated the firm, selling the patents to Japanese turntable maker BSR, which became CTI Japan which in turn created ELP Japan for continued development of the "super-audiophile" turntable. It finally reached the market in 1997 as the ELP LT-1XA Laser Turntable with a list price of US$20,500 (since reduced for subsequent models).

[edit] Technical details

  • The ELPJ laser turntable has three models available (with noise reduction and vacuum cleaning attachments extra): [1]
    • LT-1LRC - US$9,990 - 33, 45 - 7", 10", 12"
    • LT-1XRC - US$12,990 - 33, 45, 78 - 7", 10", 12"
    • LT-2XRC - US$13,990 - 33, 45, 78 - 7", 8", 9", 10", 11", 12"
  • The laser pickup uses five beams — two on each channel to track the sides of the groove, two on each channel to pick up the sound (just below the tracking beams), and a fifth to track the surface of the record and keep the pickup at a constant height, which allows for record thickness and any warping.
  • The lasers focus on a section of the groove above the level where a conventional stylus will have traveled, and below the typical depth of surface scratches, giving the possibility of like-new reproduction even from worn or scratched records.
  • The pickup output is analogue: the signal path is never converted to digital.
  • Using a laser pickup eliminates many problems associated with physical styli: record wear, horizontal tracking angle error, turntable rumble, leveling adjustment issues, inner groove distortion, channel-balance error, stereo crosstalk, anti-skating compensation, acoustic feedback, skipping, locked-groove problems, problems tracking warped, cracked, or eccentric records and cartridge hum pickup.
  • The laser turntable is, however, still extraordinarily sensitive to record cleanliness. It will play exactly what it sees. Some reviewers see this as a flaw -- others as a benefit.
  • When an LP is inserted into the tray drawer and the drawer closed, the turntable reads the surface of the LP, displaying the number of tracks. Users can then program which tracks to play, or repeat, much as a CD player operates.
  • The laser diode typically lasts 10,000 hours of playback, compared to the 500 hours recommended for a diamond stylus or 50 hours for a sapphire one.
  • Versions of the ELPJ laser turntable will play back analogue disc records at any speed from 30 to 90 RPM (+/- 0.1 RPM) and of any size from 7 to 12 inches (178 mm to 305 mm).
  • The main limitation of the pickup is that the record must be black and opaque-coloured, transparent or translucent records may not play.
  • In ten years approximately 1,200 units have been sold, primarily in Japan.

[edit] Competitors

  • The IRENE system, developed by physicist Carl Haber and installed in the Library of Congress late in 2006, uses a camera rotating around the record which takes detailed photographs of the grooves. Software then uses the digital images to reconstruct the sound. IRENE often produces a large amount of "hiss" with the recording, but is very capable of removing "pops and clicks" produced by scratches on the record surface.

[edit] References

  1. ^ ELP Laser Turntable: Price Information. Retrieved on 2008-05-17 from http://www.elpj.com/purchase/index.html.

[edit] External links

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