Roy F. Allison Interview

Roy Allison is a legend in the hi-fi loudspeaker industry, having been chief engineer at Acoustic Research when that company developed the world’s first dome midrange and first dome tweeter. He then went on to found Allison Acoustics. At 84, he’s still active in audio, acting as a consultant for a number of famous US loudspeaker manufacturers. Steve Mowry caught up with him at his home in Belmont, New Hampshire…

Roy Allison. Hi-Fi Industry Legend.

Steve Mowry: Do you consider yourself to be a loudspeaker pioneer?
Roy Allison: Well, I’ve been active in the industry since 1951, first in audio editorial work and then, beginning in 1959 with Acoustic Research, in the design and production of commercial speakers and electronics. There were others before me.

SM: Did you invent the dome tweeter?
RA: No. Edgar Villchur developed the edge-driven dome midrange unit and tweeter.

SM: Where do you see the loudspeaker industry in the next 5 to 10 years?
RA: In home applications, loudspeakers will be considered to be primarily an adjunct to television and personal computers. Aside from that, I’d expect to see much more emphasis on wireless signal transmission, especially to surround and rear speakers. In commercial applications, they will be much the same as now.

SM: What do you consider to be the greatest achievement in your career?
RA: Learning and then teaching how rooms affect loudspeaker performance and how to use that information to design much better loudspeaker systems. Only a few designers have taken advantage of these simple rules. Of course, the appropriate comment to make here is: ‘There are none so blind as those who will not see.’

SM: The transducers used in the Allison One looked proprietary. What were the design criteria for the dome tweeter, dome midrange and woofers?
RA: The midrange and tweeter units are not really domes in the usual sense. They are convex radiators, but each is driven by a voice coil at approximately half the distance from the centre to the suspension edge. Neither has a spider. The cone part of the tweeter, although convex overall, is curved inward and the outer edge is clamped through a very thin ring of latex foam to the mounting plate. Thus the radius of curvature of the cone changes as the voice coil moves, simulating a pulsating hemisphere that puts large amounts of high-frequency energy into the reverberant field all the way up to 20kHz. The midrange unit has a straight-sided cone with a flexible polyethylene edge suspension. It has extremely wide and uniform dispersion over its operating range… as does the tweeter. Neither is proprietary inasmuch as they’re not protected by patents, but they are difficult and time-consuming to make properly, and they do project relatively far out from the front cabinet panel, which complicates the grille design. They have not been imitated, probably for those reasons.

The woofers themselves are simple, very good basic designs. What makes their performance exceptional is their placement in the enclosures. Villchur said it: the woofer and the cabinet are one system. I extended the bass system to include the room boundaries.