Rich May of Sumo: An Audio Dynasty
The paragraph above sounds like something of a digression, but bear with me. The scene changes, to California in the mid '70s. A forceful personality named Jim Bongiorno, once responsible for amplifier design at Dynaco, forms a company called Great American Sound to market his humongous solid-state designs, notably one of the first-ever muscle amps, Ampzilla. For various reasons, GAS fails to work out, whereupon Mr. Bongiorno sets up a new company, Sumo, again to sell his amp designs. I think it fair to say that the original Sumo company never really gets off the ground, despite having an interesting product line, culminating in the affordable Polaris amplifier. Mr. Bongiorno sells his interest in the company, and Sumo eventually winds up being bought by another California company, Califone, best known for dominating the educational record-player market.
This is where the apparent digression is resolved: the President of Califone, Michael Custer, and Califone's chief engineer, Rich May, were in the engineering division at Marantz/Superscope in the late '70s and were involved in the design of the Esotec gear which had made such a hit among the UK audiophile community. Rich, the son of famed drive-unit engineer Ed Mayresponsible for the design of low-distortion high-power drivers for JBL and Gauss, among others (Ed designed the classic JBL 4310 studio monitor and its domestic version, the L100)is now responsible for electronic design at Sumo. Before Sumo/Califone, Rich had been designing loudspeakers at Siefert-May Labs; I met with him last November in Sumo's Chatsworth, CA plantunlike many American electronics companies, Sumo actually manufactures in the USand asked about his background.
Rich May: I've been with JBL, Superscope, Marantz, and Gauss Electrophysics, the high-speed tape duplicator. Gauss was great, because one of the bright, really bright guys in this industry, Keith Johnson of Reference Recordings, was over there. The duplicator's Keith's baby. Keith was also responsible for video disc. Keith and Paul Gregg were the original founders of Gauss, and had the idea of doing a video disk in 1969! In 1969 Gauss had a black-and-white video disk up and running.
Atkinson: You weren't working on the Gauss drive-units?
May: No. Those were my father's. I literally grew up in this industry. I've done both electronics and transducers. The last time I was at Marantz I worked under Dad, in the loudspeaker group. It was good experience. I had three years of working with him on a daily basis. We did some very interesting magnetic circuit designs for our low-distortion loudspeakers. In fact the silver-plated pole-piece that he introduced in the JBL LE seriesthe LE8, and then later the '8T as well as the LE 85, LE 75 compression drivershe did that as an experiment. It wasn't used for distortion reduction as much as it was to control the voice-coil inductance and extend the high-frequency performance.
Nobody really understood what the silver was doing, but shortly before we left JBL, I started a witch hunt, bitching about the distortion of compression drivers and trying to push the company into direct radiators. So everybody started measuring distortion: lo and behold, the LE8 had the lowest distortion of anything around. Six, seven months after Dad and I started working together at Marantz, it fell into place. We came across a very obscure reference book published in the late '20s, early '30s, called Loudspeakers, by McLaughlin. Sure enough, there were the distortion reduction characteristics of a shorted turn on the pole piece. Not a moveable shorted turn, like a conductive voice-coil former, but a flux stabilizing ring.
I guess it was a parallel program, but we actually showed the system before JBL came out with their symmetrical-field geometry drivers. We showed a symmetrical-field geometry, undercut pole piecewe called it the T-Pole. It was an outstanding loudspeaker.
Atkinson: You left Marantz, however, and went to Califone in 1981. And then Califone bought Sumo . . .
May: Califone bought Sumo and we were off and running in high-end electronics. And having a great time doing it.
Atkinson: What are your design goals as an electronic engineer? What are you trying to do with your designs?
May: Very bluntly, to reproduce music. And to do that is a very demanding thing because I'm firmly convinced we aren't measuring all the things that we need to measure to be able to numerically assess the performance of an amplifier. I grew up in the days of vacuum tubes. My first amplifiers were vacuum tubes. Fixed in the back of my mind is the line that, given two amplifiers that have the same numerical specs, the amplifier that does it with the smallest amount of negative feedback sounds better. And there's some pretty good ground rules on it. This is one of the things we strive for: every one of my designs is a stable open-loop amplifier designed for minimum distortion open-loop. We do some feedforward error correction, and very large amounts of local feedback, but we try to keep the overall loop within reason.