Interview: Karl Cartwright, Westone

Master Designer discusses Earphone/CIEM Technology

Earphones and in-ear monitors
Interview: Karl Cartwright, Westone

Hi-Fi+: How did you become interested in earphone and CIEM design in the first place? What attracted you to this product category?

KC: I love music!  Whether listening to it or playing it, music has always been very important to me. I have many childhood memories of my Dad playing Herb Alpert and the Tijuana Brass albums, or putting together reel-to-reel tapes of choral and orchestral music for the Christmas Holidays.  From the beginning, I tried to get the best stereo equipment my meagre check book could afford, which meant I was playing music in bands and creating sound-on-sound recordings with old reel to reel tape recorders.  When the Sony Walkman revolution hit in the mid-80’s, the way that people listened to music dramatically changed, and as a result, made the entire experience much more personal.  People started listening to music where they could never have enjoyed music before like when jogging, biking, and walking on the beach, etc.  This was great except for one major hitch (besides having to carry all those cassette tapes); the earpieces just would not stay in the ear.

By this time, Westone was a well-established company in the hearing healthcare industry that provided custom ear-molds for hearing instruments, communications, and hearing protection devices.  It wasn’t long before people were asking us for a solution to the portable-music problem and started making custom earpieces that would accept the Walkman style ear buds. Soon after developing the ‘ear bud custom’, I was approached by a local factory that was having communication difficulties on the production line.  Although they were using Westone’s custom earpiece with an ear bud, the lack of attenuation made it very difficult for team to clearly hear their line supervisors. To solve the problem, we discovered the earpiece had to offer more hearing protection than an earbud based system could provide. The solution was an earpiece that acted as hearing protection first and allowed for communication as well.  By using a balanced armature driver from the hearing aid world, and engineering it within a fully occluding earpiece, we were able to combine the two things this factory needed most: a clear audio signal and hearing protection.

Shortly after that, ’90 or ‘91, Bill Chrysler, who was working with Def Leppard and Rush as they were preparing for their world tours, approached me. They each had a unique problem that they were trying to solve before the tour started. With Def Leppard the volume on stage had grown to such a level that it was becoming extremely difficult for lead singer Joe Elliot to hear the vocal monitors over the guitar amplifiers on stage. With Rush, the issue revolved around the milliseconds of delay caused by all the various signal sources on stage like floor monitors, drums, guitar amps, and side-fills.  Using the same principals as we learned in the factory, we were able to sufficiently reduce the level of ambient sound in the ear to a level that the earpiece became the primary listening source. For Joe Elliot, his voice could be turned up enough in his ears that it could compete safely with the volume of the guitar amplifiers simply because the stage volume in his ears was reduced by 25 to 30 dB!  For Rush, the monitor signal provided a clear and precise listening experience as opposed to a smear from all the different signal sources on stage.

A few years later a stage-monitoring gear company, called Leabody Systems, approached me to work with them to help solve some problems Van Halen was having as they were preparing for their 1995 world tour. Leabody introduced me to the monitor engineer for the tour, Jerry Harvey.  The problem was that Alex Van Halen was using earbud style monitors and was consistently blowing them up as he cranked up the volume to compete with the stage monitors.  After describing the solutions that I had developed for Def Leppard and Rush, we decided to give it a try. We built Alex some earpieces that used balanced armature drivers and featured removable faceplates so that if a driver did fail, it could be replaced in the field.    

It was from this early first collaboration that Ultimate Ears by Westone was born!  Originally we offered both moving coil and balanced armature driver earpieces.  However, once we had introduced the UE5 Dual Driver earpiece, the balanced armature driver had proven itself as the ideal source to use within the demanding on-stage environment. A few years later we worked with Shure to create the first fully occluding universal fit in-ear monitor that was primarily planned to be used in the launch of the PSM 600 wireless monitor system.   As you know, much has changed over the ensuing years – some of them firsts for Westone some for other companies.  Through all if this change, one thing has remained the same: a fully occluding earpiece with balanced armature drivers is the first choice for most people in a critical listening environment.

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