By combining aspects of a few different headphone types, Yamaha produced an audio breakthrough that still resounds
The 1970s were heady years for fans of recorded music. Microphones, tape recorders, record players, radios, speakers, amplifiers…nearly every category of gear used to record and reproduce electronic sound was improving by leaps and bounds. Meanwhile, recording engineers were continuously outdoing each other with creative new studio techniques. It was amid this splendid ferment that engineers at Yamaha began designing a set of headphones equal to the artistry of the most ambitious musicians and the studio wizards those musicians were working with.
By the early 1970s stereo recording had progressed far beyond such simple techniques as assigning bass and rhythm guitar to the right channel and lead guitar and drums to the left channel. The apotheosis of multichannel recording was Pink Floyd’s Dark Side of the Moon, which began blowing minds in 1973. To listen to Dark Side—no, to, like, really hear it, man—you had to listen with headphones. There had been almost nothing like it before. It sounded as though the bass lines were physically flying loops around you. Keyboard runs emerged from one direction, moved through you, and kept going in the other direction. Vocalists appeared in front of you and then receded into distant guitar chords.
Thanks in part to Dark Side in the 1970s, for the first time, having a great pair of headphones was a necessity not just for audiophiles but for any ardent music fan. So a great pair of “cans” at a reasonable price was practically guaranteed to sell.
Around 1974, Yamaha made two interesting decisions about its next set of headphones, the set that would get the designation HP-1. One was to try to pursue an unconventional technology to achieve a balance of high performance and affordable cost. The other was to hire a celebrity designer to design the product. Doing the first was almost common. Doing the other less so. Doing them both at the same time was, and is, rare.
Most headphones and full-size speakers then, and now, were based on dynamic drivers, which go back to the 1920s. They use an electromagnet coil to vibrate a cone-shaped diaphragm that produces sound waves. High-end speaker manufacturers at the time were experimenting with alternatives, and there was growing enthusiasm for planar, or full-range, speakers. Headphone makers at the time meanwhile were busy working on a third type—electrostatic, or condenser, speakers. Electrostatic headphones can provide great sound, but they’re relatively expensive.
Yamaha’s plan was to find an approach to building headphones that would combine the best attributes of the various speaker types. The company’s engineers decided to create a fourth type, which they called full-drive magnetic headphones. The approach they envisioned would be “very close to condenser models, an ideal method for combining the characteristics of the condenser and the ease of use of the dynamic model,” according to an online Yamaha technology retrospective.
The idea was not new. Prior to the HP-1, a few products had hit the market trying to make use of essentially the same concept. No one had been successful, however, according to that retrospective on the HP-1. The reason, the company said, was simple: “Basically, such products were difficult to manufacture, and not much benefit was found to offset the difficulty.” Yamaha engineers figured out how to get a lot more of the benefit.
Yamaha’s headphones used a polyester diaphragm just 12 micrometers thick –exactly the same as the thickness of the tape in a C90 cassette, according to the Yamaha retrospective. A similarly thin diaphragm is also used in electrostatic (condenser) speakers. However, the Yamaha approach embedded on top of this thin diaphragm a conductive trace, similar in function to the voice coil in a dynamic speaker. The diaphragm was placed within an array of permanent magnets that created a very even magnetic field, called an isodynamic magnetic field.
In operation, the music signal flowed through the conductive trace on the diaphragm, creating a magnetic field that interacted with the isodynamic field, causing the diaphragm to move and produce sound waves. Yamaha’s big breakthrough was figuring out a way to economically print the conductive coil directly on the diaphragm. Yamaha’s references to how this was accomplished are inconsistent; they variously describe the method as printing and as “photo-etching.” Either way, the coil was a “250μ interval spiral” with five concentric rings, according to the retrospective.
Signature Series: The HP-1s got their good looks from industrial designer Mario Bellini, who would go on to become one of the most celebrated designers of the 20th century.Photo: Angelo Minichiello
The company engaged industrial designer Mario Bellini to design the product. Bellini had already designed typewriters for Olivetti and audio systems for several companies, including Brionvega, in Italy. Bellini, who was still active in 2019 at age 84, would subsequently design a camera for Fuji; vehicle interiors for Fiat and Lancia; notable buildings in Paris, Bologna, Tokyo, North Carolina, and Berlin; an enormous residential complex in the Virgin Islands; and so many other celebrated items that he is acknowledged today as one of the most accomplished industrial designers of his era.
Judging from the retrospective, Yamaha was still clearly enthralled with the Bellini design decades after its release:
Even more than simply the beauty of its appearance, the contact of the ear pads with the ear, twin headbands sharing in supporting the entire headset on the head, and its light, airy fit thanks to a universal joint connection that allowed the ear pad section and headband to move freely, must have strongly impressed the meaning of the concept of industrial design upon the audiophiles of the time….
“From the catalog of the time, you can see the development team's enthusiasm to try to create something from zero that had never previously been seen anywhere in the world,” the retrospective’s HP-1 history concludes.
The enthusiasm was merited. In devising a method to manufacture the diaphragms economically, Yamaha had finally succeeded where other audio companies had failed. Yamaha called its headphone technology “orthodynamic.” Today, the technology is typically referred to as planar magnetic or, less commonly, isodynamic.
Three Generations: Audiophile and headphone enthusiast Angelo Minichiello took 37 years to acquire three generations of Yamaha “orthodynamic” headphones (from left): the HP-1 (1976), the YH-100 (1981), and the YH-1000 (1978).Photo: Angelo Minichiello
The HP-1 headphones were priced at about US $200 upon release in 1976, or $900 in 2019 dollars. Pricey, but not outrageously so. They were immediately praised for both their sound quality and their design. HP-1s are still well regarded by those who can get their hands on working models today.
A Yamaha spokesman declined to release sales figures. The company is still producing headphones, mostly of the earbud variety, but there are still a few over-the-ear models in its lineup.
Dark Side of the Moon remained ranked in the Billboard Top 200 for 741 consecutive weeks—over 14 years—in part because of its reputation as providing a stupendous headphone experience. With subsequent sales spikes, its cumulative residence on the charts is well in excess of 900 weeks. No other album comes close to that record, and you better believe that pun was intended.