In just a few short years, relatively speaking, Japanese company DS Audio has stimulated the imagination of analogue-loving audio enthusiasts from around the world with its reinvented optical cartridge. While the optical cartridge is said to be first conceptualised back in the 1940s, with Toshiba launching a moderately successful working model in the 1970s, the technology has flourished in the last couple of decades thanks to Digital Stream Corporation’s (AKA DS Audio) refinements using modern LED innovations. Since that crucial step in its evolution, the optical cartridge, as perfected by DS Audio, has climbed to the upper echelons of audio desirability. What’s more, DS Audio stands alone as the sole major manufacturer of optical cartridges worldwide. I visited the company’s factory following the Tokyo International Audio Show 2025 (feature here). Here’s what I discovered.
He Saw The Light
I’m picked-up by none other than company CEO Tetsuaki Aoyagi-san who’s driving the 40 minute stretch from my hotel in Ginza, Tokyo, to the DS Audio facility. We arrive at a serene concrete-clad corner of Kanagawa, where, in a semi-commercial area, an unassuming building hides the complexities behind one of analogue audio’s standout success stories. DS Audio has achieved quite the stellar success by reinventing Toshiba’s optical cartridge, bringing proprietary innovation to the original concept. (Fun fact: Sharp Corporation and other Japanese companies also produced early optical cartridges).
A bit of background. Digital Stream Corporation supplies optical technologies used in the production of computer mice and joysticks, among other devices, with clients including multi-nationals such as Microsoft, Oracle, KUKA Robotics, Sharp, Sony, NEC, Asahi Kasei, among others. Laser light sources, such as LiDAR, are produced for the medical industry. Yeah, it’s safe to say that when it comes to optical-based technologies Digital Stream Corporation knows a thing or two.
Digital Stream Corporation was originally founded by Aoyagi’s father in 1988, with Aoyagi joining the company with an aim to introducing fresh ideas and viewpoints. As with many company origins, the journey started rather fortuitously.
Aoyagi told the story of his early days at Digital Stream Corporation where he was introduced to Yamada-san, a company consultant and music lover who owned a Toshiba optical cartridge. One day, as they listened to music together, Yamada-san played Michael Jackson’s “Thriller”. The sonic reproduction had a profound impact on Aoyagi. As impressed as he was with the vivid and engaging sound, he was also bewildered by the light emitting from the cartridge. Yamada explained the optical cartridge principle and encouraged Aoyagi to experiment with the technology. Especially in light (pun intended) of his access to DS Audio’s extensive optical technology expertise and the growing LED prevalence at that time.
Indeed, Aoyagi was curious and envisaged the potential. He also had a nascent desire to create products that bring joy while reproducing music to the highest standards.
He dismantled the cartridge and was surprised by its relative simplicity. He then visited Akihabara (Tokyo’s electronics district) and stocked-up on LED and photo detector parts to build his own interpretation of an optical cartridge. Upon building his first cartridge from the Akihabara parts, Aoyagi heard a sonic clarity that showed great promise, albeit at that stage, with a rather low output.
Aoyagi-san shows early DS Audio cartridges.
Further investigations and prototype development, including refinements in cross-talk/channel separation, and the breakthrough development of the required RIAA equalisation/adjustment electronics, led to photo detector-based cartridges (which are 100% analogue devices) that were the predecessors to DS Audio’s current products. So, after those promising trials, Aoyagi established DS Audio in 2013 as the audio division of Digital Stream Corporation.
Optical Illusions
We now enter a boardroom where Aoyagi takes us through how DS Audio came about. Right up to the point where DS Audio now produces a six-strong cartridge line-up (with a seventh mono model), a selection of equalisers at all price points, and a growing range of analogue accessories.
After DS Audio entered the market, its debut products quickly captured the imagination of analogue audio enthusiasts around the world. Aoyagi succeeded in renewing interest in optical cartridge technology. That’s no mean feat and showed both courage and conviction because not only at the time, and even to this day, it would be fair to say that over 90% of the cartridge market is dominated by Moving Magnet (MM) and Moving Coil (MC) technologies.
Naturally, growth was part of Aoyagi’s corporate plan. Because manufacturing an optical cartridge is relatively specialised, he decided in 2022 to action a strategy to open just the equaliser technology to other manufacturers, while maintaining cartridge production in-house (in addition to its own equaliser options). That new ‘open-source’ policy resulted in a number of high profile electronics companies producing their own equaliser components, opening up the optical cartridge technology to a much wider consumer base, now with mix and match options.
As Aoyagi tells me, “Many manufacturers have asked me, ‘How much is the licence fee’. I never asked for licence fee. We need to build-up the market together… we don’t want to make money from manufacturers. Plus, the equaliser makes a massive difference in the sound, so every manufacturer offers variations in sound for different consumer tastes. Customers need choice.”
He went on to say, “I want to build-up the optical cartridge market and I think we are doing it. A few years ago, in High End Munich, only our distributor used DS Audio cartridges. Slowly we became more known and, this year, ten exhibitors showed with DS Audio cartridges. I’m very appreciative of manufacturers who are producing equalisers. They believe in the optical cartridge technology.”
Finally, Aoyagi reaffirms his original kernel of spirit and passion that bloomed into today’s company by stating, “The strong desire to ‘create something new that brings joy to people’ led to the founding of DS Audio, with the brand concept ‘Creating the future of analog music.’ It became a significant driving force toward the development of products like the optical cartridge and the eccentricity detection stabilizer, etc. This passion remains unchanged even now.”
Yes, it’s all in the optics, as they say… and on that note, let’s hit the factory floor where I’ll show the manufacturing methodologies and the strict precision behind DS Audio’s remarkable cartridges.
Gallery
Two rows of assembly stations where cartridges are assembled and aligned. The team can produce up to 300 cartridges per week. Each craftsperson uses a custom alignment ‘jig’ designed by DS Audio.
The shade plate is a miniature marvel of precision machining.
The shading plate is checked for symmetry and accuracy after the cutting/machining process.
Perfect alignment and angling between the various cartridge parts is achieved via the DS Audio-designed jig. The jig’s magnifier is coupled to a computer monitor that displays pre-marked position guides allowing very precise alignment.
Technician performing a number of tests, including cartridge register and output. The same tests are performed from the entry level DS-E3 model right up to the flagship Grand Master cartridge.
Each cartridge is magnified via microscope and displayed on a dedicated computer monitor. Further checks are conducted for optimum symmetry and precise centring of all aspects of the cartridge, including the shading plate, cantilever and stylus.
Records and measurements are kept for each cartridge going right back to the very first production samples. This helps in identifying an individual unit no matter the timeline or the cartridge’s place of origin.
Finished product: the Grand Master EX cartridge.
Near-complete DS Audio Grand Master equaliser with its separate power supply featuring a capacitor bank (below the gold metal plates) that rivals most amplifiers.
DS Audio’s ES-002 Eccentricity Detection Stabilizer is demonstrated in the company’s listening room. Several settings, from 300 to 20 microns of eccentricity (off-centre variance from the spindle) were A/B-ed. The sound difference was evident. Once aligned there was subtly more detail, stage depth, and overall clarity.
The listening and testing reference system featuring custom DS Audio integrated amplifier and YG Acoustics Haley loudspeakers (source is Clearaudio Innovation with Graham Engineering Phantom Elite tonearm).
… Edgar Kramer
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DS Audio – Digital Stream Corporation
4-50-40, Kamitsuruma-Honcho,
Minami-ku, Sagamihara, Kanagawa 252-0318
Japan
+81 427 47 0900
https://ds-audio-w.biz/