I remember with great clarity my first meeting with Infinity founder Arnie Nudell after he left the company. My friend and TAS publisher, Harry Pearson, had called me out of concern for Arnie's mental health hours after the incident. "Arnie's left Infinity," said HP, after having tracked me down while I was on vacation in Colorado. "He'll no doubt be devastated. You have to help him. He's our friend." Turned out that Arnie too was in Colorado, not more than a few thousand yards away from me. Infinity had been founded in his garage some 40 years earlier. It was his life, his passion, his entire raison d'être. I expected to find a broken man. What I found surprised me. Instead of depressed he was almost effervescent as if the weight of the world had been lifted from his shoulders. The first thing he wanted to show me was a new tweeter: a round ribbon he was excited about. "The basis of every great loudspeaker begins with the tweeter," he proclaimed, and that's something I've managed to cling to ever since. Reader Steve Bruzonsky asked me about a tweeter made famous by Infinity in its 2000 II model called the Walsh. He owned a pair back in 1974 and wondered how they worked and whatever happened to them. Here's a picture of it. The Walsh Tweeter is that inverted gold cone on top of the Infinity box. Essentially a standard tweeter motor of voice coil and magnet attached to an ice cream cone shape of thin metal with damping inside. Invented by Lincoln Walsh, its best known association is with the Ohm Loudspeaker company who acquired the patents. The technology seems rather simple: instead of a traditional horizontal dome acting as a hemispherical piston facing the listener, the Walsh was a vertical pump attempting a 360˚ sphere of high frequencies. Many people still covet this design though it struggled with higher frequencies because of its high mass and large shape. The technique reminds me of another similar driver approach in the MBL speaker. The MBL incorporates the same idea of a vertical diaphragm attached to the voice coil and magnet of a standard driver. Instead of the ice cream cone shape of the Walsh, a flexible metal balloon is used instead. Here's a picture of an MBL type driver. You can see the spider and magnet of a standard woofer that drives it. Both are designed to produce radiating 360˚ spheres of sound pressure: the MBL as an expanding and contracting balloon, the Walsh as a rigid pump. Of course, we understand there's no such thing as a perfect radiator unless we want to get into massless plasma drivers which get us as close to perfect as we're likely to come - though they are as impractical as monkeys typing novels. A fun bit of audio history.
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