Optical Turntables and Laser Cartridges-Are They The Future?

Let There Be Light

Image Credit DS Audio. DS 002 Optical Cartridge

The ultimate pickup system for vinyl would be one that doesn’t touch the vinyl, so produces no wear, and the vinyl remains as pristine as the day you bought it, and sounds just as good as the best esoteric cartridges. Well, we’re not quite there yet. There have been three developments along the lines of using lasers and light to read vinyl, only two of which are contact free.

Finial & ELP

Lasers were first introduced for reading vinyl groove information almost 40 years ago. The first functioning laser turntable, the LT-1, was made by Finial Technology and had a projected street price of $3750. Due to major economic issues the turntable never got any traction in the vinyl market, and finally they were purchased by Japanese turntable manufacturer BSR (Birmingham Sound Reproducers). Japan BSR then created ELP Japan to continue the development and manufacture of  the turntable, a process that took many years. Using five laser beams and costing a reported $15,000, it is hardly for the average audiophile, and it cannot read clear or colored vinyl. However, it is still sold today as a bespoke product, only  being manufactured on an order by order basis. Detailed technical specifications seem to be impossible to find. See here for further information.

Image Credit ELP. LT Basic Player

IRENE – Image, Reconstruct, Erase Noise, Etc.

A second stylus free turntable development that used a different type of technology, the IRENE system or Image Reconstruct, Erase Noise, Etc. was invented by physicist Carl Haber and developed by the Northeast Document Conservation Center (NEDCC), It is impractical for home use. It is used by the Library of Congress and other institutions to retrieve the original audio from old and damaged discs. It uses a 3D and 2D camera system to scan the grooves, the images of which are then analyzed by software which then turns them into sound. See IRENE and NEDCC for further details.

Image Credit NEDCC. IRENE Disc Scanner

DS Audio

That brings us to modern day with the DS W2 Audio Optical Cartridge system shown at CES2018.

Image Credit DS Audio. DS 002 Optical Cartridge

DS 002 Optical Cartridge

Image Credit DS Audio. DS 002 Optical Cartridge Pre-Amplifier

This optical cartridge system, costing about $13,000, still uses a needle and cantilever, not bouncing the light directly off the vinyl surface, but instead bouncing it off the cantilever assembly. So although the cantilever assembly is lighter than a conventional assembly, not having to support coils and magnets, it is still a needle in the groove and the cantilever needs to be elastically suspended.

DS Audio manufactures three models that use this laser technology, DSMASTER 1, DS-W2 and the DS002.

Who is DS Audio?

DS Audio is a newly formed audio business group within Digital Stream Corporation  (DSC). DSC has been in the laser optics market for over 25 years, providing industrial laser optic systems for the optical disc market, medical and optical measurement systems, co-developing the optical mouse with Microsoft. They have a 95% market share for their optical disc and laser products. They are renowned for their high quality products that provide 100% scanning accuracy and in 2011 received Japans “300 Excellent Companies In Manufacturing” prize from the Ministry of Economy, Trade and Industry.

Cartridge Technology – A Brief Overview

MC & MM cartridges rely on coils and magnets to generate the electrical signal. These optical cartridges use a beam of light to detect cantilever movement.  As seen in the following two diagrams this makes the cartridge much lighter and more agile. It also has the advantage of removing the magnetic field inside the cartridge with its potential impact on the cantilevers’ movement.

Note: Two other types of technology are also used in phono cartridges: the crystal/ceramic cartridge by Astatic and the strain gauge cartridge by Soundsmith.

Image Credit DS Audio. Cartridge Construction Concept

Image Credit DS Audio. Cartridge Light Path

Any magnetic electrical generator system requires a mechanical force to move the armature (stylus & cantilever) in order to create an electrical signal (Faradays Law of Induction). This movement induces a voltage in the coil(s) which in turn imposes a force on the magnet, the coils now becoming an electromagnet (Lenz’s Law). This opposing force will tend to inhibit the movement of the cantilever, and it is claimed, that this force restricts the ability of the stylus to exactly follow the vinyl cut. The DS Audio optical system exhibits no such reactive force, and being lighter, the stylus assembly can more faithfully trace the vinyl cut.

MC and MM cartridges create a voltage that is proportional to the velocity of the cantilever (the attached magnet, coils or variable reluctance), NOT its displacement. So for a fixed amplitude cut their outputs rise at higher frequencies by 6dB/octave, being very low at bass frequencies. This phenomenon requires equalization as it impacts signal-to-noise ratio, pre-amp overload and cartridge tracking. The optical cartridge system provides a voltage output that is proportional to the amplitude of the vinyl cut, and is virtually independent of frequency, being equally capable of handling 1Hz just as well as 20KHz. The optical cartridge signal, therefore, only requires an RIAA correction curve in order to meet the correct playback frequency response.

Whether the above benefits translate into a better sounding cartridge, I don’t know. It all depends on other mechanical factors, the stylus design and how the optical path is translated into an electrical signal.

By all reports and reviews it would appear that this design has some huge benefits, generally sounding excellent, with just a few shortcomings. It’s the usual cartridge balancing act.

Want to Know More?

Click here for the DS Audio web site.

Click here for a review of the DS 002 by The Absolute Sound.

For more on DS Audio optical products check out these posts:

It’s expensive, very expensive, and it comes with its own special pre-amp. So, is all that cost worth it, and does it outshine the most exotic conventional cartridges? Read the DS 002 reviews and listen to sound samples here. Then let you and your bank manager be the judge.