DS Audio DS 002 Optical Cartridge

Let There Be Light

Equipment report
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DS Audio DS 002
DS Audio DS 002 Optical Cartridge

A long time before most of you were born, grandpa here used to use a phono cartridge called the Decca London, whose chief virtue was the elimination of what Decca called “cantilever haze.” “What’s that?” I hear you whippersnappers asking. Well, kiddies, it’s like this: All phono cartridges convert the physical vibrations of a stylus into an electrical signal. Most use a cantilever—a thin metal tube equipped with a flexible rubber ring that acts as a fulcrum—to transmit those vibrations from the stylus at one end to the moving magnets or coils at the other. Now Decca claimed that the resonances of that cantilever, the damping effect of the rubber fulcrum, and the sheer mass of the magnetic engine at the far end of this virtual “see-saw” caused losses of clarity, transient speed, and dynamic range—i.e., “cantilever haze.” Decca’s way of lifting that haze was to eliminate the cantilever, using an angled iron armature in its place, with a stylus on the playing end and no moving parts on the other. Instead, the armature was situated directly within a magnetic field, surrounded on top and to its sides by stationary magnets and coils. The iron armature was magnetized by the magnets, and its movement up-and-down and side-to-side caused lines of magnetic flux to cut through the coils, inducing a voltage. Decca called the system “positive scanning.”

“Why are you telling us this story, gramps,” I hear you asking, “when the cartridge under review, the DS Audio DS 002, has absolutely nothing in common with Decca cartridges? Are you going soft in the head?” Well, first, I resent that question. You should show some respect for your elders. And, second, smartasses, the DS 002 does have something in common with the Decca London. It, too, eliminates (or greatly reduces) cantilever haze—only it does so by entirely different means. Rather than a fixed array of magnets and coils, it uses a fixed LED and optical sensor to turn the vibrations of its Shibata-tipped cantilever into electricity.

Two years ago I reviewed the first iteration of a DS Audio cartridge, the DS-W1 “Night Rider,” and though, as you will soon see, several things have changed for the better in the DS 002, the basic operating system remains the same. If I may quote from that review without again being accused of going soft in the head, here is how it works: “The cartridge uses a light source (a miniature LED) that is powered via tonearm cables and internal tonearm wiring by an outboard equalizer/power supply (which you must purchase along with the cartridge and which replaces your phonostage). The record-groove vibrations transmitted by the stylus/cantilever modulates this LED light by means of an ultra-low-mass screen or shutter attached to the cantilever. This modulated light is picked up by the photodiode, which converts the light into an electrical signal, sending it back through the tonearm wires and interconnects to the equalizer/power supply unit where it is RIAA-equalized and amplified into a line-level output.”

According to DS Audio, removing the coils and magnets not only makes the cartridge itself lighter (a mere 8.1 grams) and more responsive (thanks to the considerable reduction in moving mass), it also eliminates the inevitable counter-effect those magnets and coils have on cantilever movement due to weight, friction, and eddy currents. Unlike the engine of a moving-coil or a moving-magnet cartridge, DS Audio’s optical system is said to have “absolutely no [reciprocal] effect on the vibration of the stylus/cantilever system.”

In addition, DS Audio claims that its optical cartridge offers a superior mechanical/electrical interface. Conventional moving-coil or moving-magnet cartridges read the velocity of a stylus’ vibrations, so the strength of their output signal depends on how fast the stylus moves. The DS 002, on the other hand, reads the amplitude of a stylus’ vibrations, so the strength of its output signal depends on how far the stylus moves.

According to DS Audio, this is significant because velocity-proportional devices move faster at higher frequencies, thus making the voltage of those frequencies disproportionately strong (and that of the slower-vibrating bass notes relatively weak). Although the RIAA circuits in phonostages are intended to invert this accentuation of the treble and reduction of the bass, and loading mc cartridges down can also damp this treble pre-emphasis, it is a fact that mc’s, in particular, are relatively “bright” by nature. Thanks to its amplitude-proportional technology, the DS 002 electrical output is not frequency dependent. Thus, it does not exaggerate the treble or reduce the bass, making RIAA equalization relatively simple and extending linear low-end response to well below what mm and mc’s are typically capable of. (In theory an optical cartridge can detect signals as low as 1Hz.)

What has changed in the DS 002 from the original “Night Rider” (which was essentially Toshiba’s optical cartridge from the 1960s updated with present-day materials) is two-fold. First, the LED and photo sensor have been moved closer to the stylus, so that the amplitude of its vibrations (modulated by the screen) can be read with greater precision. Second, thanks to the input of several moving-coil experts (including the folks at Lyra), DS Audio has gone to a more traditional stylus suspension, where the cantilever is held rigidly in place via a small tension wire coming out its back and secured by a setscrew. Once again this greater rigidity allows for better reading of stylus vibration.

These two relatively small changes have made a huge change in the sound of the cartridge. Where I felt the original “Night Rider” sounded like a decent moving magnet, the DS 002 sounds like…well, like nothing I’ve ever heard before—save for a Decca in the way it eliminates “cantilever haze” (though in every other key regard it is much better than that the last Decca I reviewed ten years ago, the $5295 London Reference).

You simply have to listen to a cartridge without “cantilever haze” to understand how accustomed we are to hearing it, even through many of the finest moving coils. With the DS 002, it is almost literally as if a thin curtain of fog lying between you and the music has been lifted, making for a sudden and remarkable improvement in directness, clarity, and realism—particularly in the heart of the midband. To put this plainly, you hear a lot more of what was recorded, including a good deal you haven’t heard as clearly (or at all) in the past.

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