Eddie Villchur passed away peacefully at his home on Sunday eve (Oct. 16, 2011). Many may know that Eddie is the father of multi-band compression- something found in almost all modern hearing aids. What you may not know is that Eddie was also the inventor of the modern day loudspeaker. I have had the opportunity of spending some time with him over the years and even hosted him at a local conference called Seminars on Audition which I sponsor. I believe that it was in 1988 or 1989. I also had the chance to interview him several years ago for the Canadian Hearing Report which is the official journal of the Canadian Academy of Audiology and some of the excerpts are attached below with questions in italics and his answers in bold print.
Loudspeakers are the mainstay of the audio field and without Eddie’s insights and genius we would still be lugging around large, heavy speakers where ever we go.
The story as I remember it was that Eddie was busy trying to make the perfect mechanical loudspeaker and he was almost finished hand wiring an entire stack of pistons that would drive the speaker cone. At the same time he was lecturing at a university (I believe Albert Einstein in New York) and in the middle of his class it occurred to him that he could just let the trapped mass of air in an enclosed box do the work of the pistons. He ran home (he mentioned something about abruptly leaving the lecture but I can’t remember if this was the actual case or not), threw away all of his pistons and began sealing up the air holes in the speaker enclosure. The air suspension loudspeaker was born.
MC: One of the many things that you are well known for is the “acoustic suspension loudspeaker” which dramatically improved the bass response and miniaturized the size of loudspeakers.
EV: Well, back in the 1950s you could buy an amplifier for home use with a half of 1% distortion or less, even at the frequency extremes and at full rated power. With loudspeakers, however, distortion figures in the bass were 20 to 100 times that amount. When I looked into it I found that the largest fundamental problem was the non-linearity of the loudspeaker suspensions. That is, when the speaker cone makes large excursions for high-intensity bass sounds, the mechanical suspensions holding the cone in place don’t stretch evenly and start to bind. It occurred to me that the volume of air in the cabinet is a near-perfect spring, far more linear than the best mechanical suspension system. All you would have to do to use it is throw away most of the elastic stiffness of the mechanical system and replace it with the acoustic stiffness of the volume of air in the cabinet (hence the name “acoustic suspension”). The free-air resonance of the speaker becomes subsonic, and is raised to its operating value by the elastic stiffness of the air. This system reduces bass distortion, extends bass response, and requires reducing the size of the cabinet.
MC: I seem to recall that your name is also associated with loudspeaker tweeters.
EV: That is true; I developed the dome tweeter. In those days, in order to make high-frequency tweeters, they shrunk the size of the large cone speakers, but they couldn’t go too far because the voice coil became too small to handle enough power. What I did was to place the voice coil at the large diameter of the diaphragm, and when you do that the shape of the diaphragm emerges almost naturally as a dome.
MC: I recall a story that you had told me that some people in the physics and engineering fields thought that you were violating the laws of physics and that your loudspeaker was an impossibility.
EV: There was a substantial amount of literature showing that the acoustic suspension loudspeaker system couldn’t work. A large part of the literature “proved” that the system violated the laws of physics and couldn’t work. But today almost all speakers are either acoustic suspension or acoustic suspension combined with bass reflex, and one of my speakers is on display at the Smithsonian Institution.
… and finally, Eddie lived in Woodstock, New York, so I had to ask this next question…
MC: My last question is that since you live in Woodstock, New York, do you have anything to say about Max Yasgur’s farm and the 1969 Woodstock music festival?
EV: Every once in a while people come up here to my place ask if I can show them how to get to Yasgur’s farm, where the festival took place. I point south and say about 60 miles that way. They don’t believe me and think I am putting them down. The music festival took place about 60 miles from here and had nothing to do with Woodstock. Woodstock had a glamorous name I guess, and we now have all these recording studios here.
Thank you for your contributions Eddie. If there was ever a life to celebrate, this is it.
