Vol 6, issue 11

Laser turntables - when lasers get groovy

14 November 2011

By James Hayes

Laser turntables make light work of playing gramophone records without the need for scratchy styli, and claim to beam into hidden areas of sonic data.

Audio digital recovery and restoration technologies have, in recent years, attracted interest from music labels keen to tap into the commercial opportunities of releasing archive recordings for a new generation of consumers. At the same time sound preservationists and recording engineers are intrigued by new ways to 'release' sounds locked into old-fashioned recording media.

In recent decades the necessity to preserve historic archive recordings for national cultural history has become a matter of great importance – whether they be records of statesmen making historically-important broadcasts or legendary poets reading their own work, shellac, like silver nitrate film stock, is a fragile base medium. Moreover, aged recordings have been damaged by mishandling and over-play down the years.

Some of the greatest recordings exist as 78rpm shellac discs. Many only exist on 33rpm or 45rpm vinyl recordings where original studio tape masters have been lost.Tranfers from old-to-new generation formats are not new; since LPs first came about there have been transfers from 78rpm recordings for the nostalgia market; but as recordings of jazz greats, for example, have been re- evaluated from being popular entertainment to high art, it has created a lucrative market for the processed re-issue of old music.

Among the most specialised applications for re-accessing archive gramophone records is the laser (or optical) turntable: a turntable that uses lasers as a 'pick up', rather than a solid material like steel, sapphire, or diamond. Using laser there is no physical contact to play the inscribed, modulated spiral groove that turns a disc into an analogue sound storage medium.

In addition to appealing to the music industry and sound archivist, laser turntables hold appeal to audiophiles and collectors drawn to the idea of not only being able to direct-play their precious shellac or vinyl records without further gouging to the grooves, but also to a listening experience that releases audial detail that conventional styli cannot access. Similar to a CD, the laser beam traces the signal undulations inscribed in the disc's surface without friction and, therefore, without wear to the groove or mass of the surface: the signals are then converted into standard audio that can be channelled to speakers or to other audio devices.

The laser turntable concept was first developed in the 1970s as a possible replacement for (and improvement on) conventional turntables, before the CD format loomed. Inventor William Heine presented a paper entitled 'A Laser Scanning Phonograph Record Player' to the Audio Engineering Society in 1977: his 'Laserphone' prototype, patented a year earlier, used a single 2.2mw Helium-neon laser for tracking a record groove, and reproducing the stereo audio in real time.

Heine's notion attracted no commercial interest from the audio manufacturers, and it wasn't until 20 years later that a fully-fledged laser turntable, the LT-1XA, entered the mass market from Japanese brand ELP. The LT-1XA had its antecedence in Stanford University graduate Robert Reis's master's thesis on 'An Optical Turntable'. With Stanford engineer Robert Stoddard, Reis set-up Finial Technology to commercially develop the technology.

A proof-of-concept, the Finial LT-1 was completed two years later and presented at the Consumer Electronics Show 1986, but was so accurate that it 'played' particles of dirt and dust on the record rather than pushing them aside. Despite their apparent similarities with CD players, laser turntables have always been a premium-priced electronica: the LT-a had a $2,500 retail price.

Market development

The Finial turntable never went into mass production. Development coincided with the advent of the compact disc, which imposed a shelf-life on vinyl record and record player sales. Liquidated in 1989, Finial's patents were acquired by Japanese turntable maker BSR, later CTI Japan, which created ELP Japan for continued development of the 'super-audiophile' turntable concept.

Finally launched in 1997, the ELP LT-1XA Laser Turntable, with a list price of $20,500, was marketed as a professional tool for radio stations, for example, wanting to digitise vinyl stock. However, the Standard LT models – the LT-1STD and LT-2STD – have since shipped some 1,800 units to a range of different quarters, including audiophiles able to afford its list price of £5,000-£6,000. The latest High-Ends Models – the LT-1LNP, LT-1XNP, and LT-2XNP – launched in March this year with over 20 models already sold; prices range from £11,550 to £15,760.

One of its biggest appeals for audiophiles is the fact that its electronics are entirely analogue – the signal is not digitised as part of the signalling and playback process. Analogue purists argue that sound that is captured and preserved using analogue technology should only be played using analogue decks. Archive transfers to digital media can compromise this, although engineers have found ways to reproduce an 'analogue sound' from a digital format.

Lasers also promise to scan more of the recorded sound than styli are able to convey. Even the best-tooled styli do not reach the entire range of indentations in a recording groove. This has long been known but has been an accepted limitation of the gramophone listening experience, and the sonic range of 331/3 microgroove (LP) provided sufficiently high fidelity for accurate reproduction. Listeners to the first microgroove hi-fi records probably did not care that they were not hearing all the data that LPs contained, because the quality was impressive enough, and a demonstrable improvement on coarse groove 78rpm platters.

The LT player's five lasers – one on each channel to track the sides of the groove, one 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 – focus on a section of the groove above the level where a conventional stylus will have travelled, and below the typical depth of surface scratches. This gives the possibility of like-new reproduction even from worn or scratched records, its makers claim. (The ELP's laser diodes claim a typical life of 10,000 hours, compared to the circa-500 hours recommended for a diamond stylus.)

This means that, in the same way that digital restorations of old movies reveal detail that was not viewed by original cinema audiences, playing old analogue audio recordings on 21st century replay technology can convey sound qualities that have remained latent since the original performance was committed to vinyl or shellac. 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 7in to 12in (180 to 300 mm).