The Master1 is DS Audio’s current top-of-the-line optical cartridge. At $22,500 ($7500 for the cartridge and $15,000 for the Master1 equalizer designed to go with it), it is considerably more expensive than the Japanese firm’s other offerings—and than virtually every other phono cartridge on the market today. However, unlike a top-of-the-line Clearaudio or Lyra or Air Tight or Ortofon or Koetsu, DS Audio’s flagship cart and equalizer require no third-party phonostage. Given how much the best phono preamps cost (the superb Soulution 755, for example, is $72,000 all by its lonesome), that $22,500 price tag begins to look more borderline nuts than outright insane, and when you add to this the fact that the Master1 cartridge does not have to be used with its companion Master1 EQ—that it can be paired with DS’s other, far-less-expensive processors (the $1500 DS-E1, $2750 DS-002, or the $8500 DS-W2)—the combined price for cart and preamp drops below the cost of a Clearaudio Goldfinger Statement or an Air Tight Opus-1 or a Lyra Etna SL or a Koetsu Blue Lace without a phonostage.
No matter which of these DS equalizers tickles your fancy, you’re going to have to buy one of them, since, for reasons I will explain, none of the DS optical cartridges works with a conventional phono preamp and conventional RIAA equalization. I’d like to be able to tell you that you’ll get the same sonic results from the bargain-priced DS-002 that you get from the big-ticket Master1 EQ, but you won’t. So if you want the sound I’m about to describe, you’ll have to go whole hog. You will also have to do some tweaking.
How a DS Audio Optical Cartridge and Equalizer Work
Before I get to setup and sonics, I’m going to tell you how optical cartridges and their equalizers work. Although I’ve explained this technology twice before (when I reviewed the DS-W1 and DS-002), the information is worth repeating, as the way an optical cartridge produces voltages and its equalizer processes them is not intuitive or conventional.
First, to make this clear from the start, an optical cartridge is a completely analog device. There is nothing digital about it. Like mm’s and mc’s, it reads the information stored in record grooves by means of the mechanical vibrations of a stylus. But where mm and mc cartridges produce tiny voltages by transmitting those vibrations to a magnet or a coil, which subsequently vibrates within a magnetic field in sympathy with the stylus, DS audio optical cartridges do not transmit vibrations to relatively massive moving objects situated at the far end of a cantilever. Instead, they generate signals by capturing changes in brightness, using an internal LED as a fixed light source, internal photoelectric diodes (photo cells) as receptors, and a very thin opaque plate (a mere 100 microns thick) mounted directly behind the stylus as the vibrating system. (See the illo on the following page.) Moving up and down and side to side in tandem with the motion of the stylus to which it is attached, this tiny plate intermittently blocks the light from the LED that is hitting the photo receptors for the left and right channels, generating variable voltages in the photoelectric diodes by varying the amount of light and shade they see.
Because mm’s and mc’s generate electricity by cutting through a fixed magnetic field, magnetic resistance always occurs whenever the magnet or coil vibrates. Since an optical cartridge only reads changes in brightness, no magnetic resistance is generated when its stylus vibrates. Since there is no magnetic resistance, the tip of the stylus can move more smoothly in the groove, without the impediment of a counterforce. This elimination of reciprocal magnetic resistance to stylus movement, says DS Audio, is the primary advantage of optical cartridge technology, although the elimination of the moving mass of coils and magnets is a second, large, closely related one.
A third is what DS Audio claims is 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 Master1, 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, 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 further dampen 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 Master1’s electrical output is not frequency dependent, at least according to DS Audio. Thus it does not exaggerate the treble or reduce the bass, making 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.)
The equalization and amplification of the cartridge’s electrical signal are taken care of by the Master1 EQ, which also supplies the voltage to power the cartridge’s internal LED and photoelectric sensors, feeding current to the cartridge through the ground legs of the interconnects running between the tonearm and the processor, and receiving the output from the Master1 (a robust 50mV) via the interconnect’s positive legs.