Hi guys,
I'm just back in from a road trip to retrieve a "pick up only" ebay purchase for a friend. These trips often yield unexpected rewards, but this time I am stunned.
For years now I have been fascinated by the history of the coaxial speaker, from the early Bell Labs patents through the 1930s Western Electric, RCA and System Eckmiller commercial systems to the 1940s debut of the Altec Lansing 604 Duplex, RCA Duo-cone and other familiar coaxial drivers. One pivotal development was the limited production in 1943 of the Altec Lansing 601, a 15" field coil Duplex that was soon replaced by the 604 permanent magnet model. This fascinating speaker was built using a Utah stamped steel basket, what appears to be a modified form of the Altec large format 287 driver field structure pressed into service for the woofer motor, and the 801 small format driver installed on the rear and speaking through a path bored through the woofer center pole into a beautiful little handmade metal cell horn.
I have often stated that I hoped to see an example of the 601 before I die. Rumor was that they only produced 100 of the 601 before replacing it with the 604, and they are incredibly scarce these days. I have only been able to assemble some literature on them from the old days, and a picture or two from Japanese audio collector magazines. A friend owns a 601 multicellular horn and 1200Hz. crossover, but that is as close as I had come in six years of searching to seeing a 601.
Well now I can die happy! The fellow I visited pulled a complete, original, near mint 601 out of a box as soon as I arrived. As soon as I regained consciousness, I examined it and took a few pictures. As can been seen from the pictures, it uses the Utah basket, likely chosen because the cast frame Lansing baskets of the time were designed for a rectangular motor. Altec was using this basket in other drivers at the time, such as the 815U installed in early to mid 1940s Iconics. The 2" voice coil of the early Lansing woofers is retained, along with the Magnavox-sourced die cut phenolic spider. From the information on the label, the two field coils were wired in series and fed from a 330VDC supply, just like the Iconic.
Lansing and Hilliard were hard at work on converting the Altec (formerly Lansing) family of drivers to permanent magnet duty at the time, so it is no wonder that the 601 had a short production life. Suprisingly, the serial number of this driver is 150, so they made at least that many. The 604 was introduced in 1944 as a great improvement, with its 3" woofer voice coil, permanent magnet structures and easily replaceable woofer cone assembly and high frequency diaphragm with tangential compliance. Even so, the 601 stands as a landmark achievement. I have been collecting 15" Utah drivers for a while to obtain the baskets, and one of my "back burner" goals is to someday tool up and produce a few pairs of 601 replicas.
I have begun work on a project to photograph my collection and assemble photos of many other rarities, all soon to be published on this site. For now though, I just had to share some pictures of the 601!
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