Holy grail driver

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!

Thanks Steve

For sharing with us pictures of that coax driver. I look forward to seeing your collection up on the site. Is that a bakalite spider?? It looks like you can see right to the voice coil.

Rob:applaud:

'nuff said!

Cool.

Hi Rob,

Yes, that is a Bakelite spider, molded from phenolic resin and cloth and die cut. An engineer at Magnavox obtained a patent for this technology in 1933. I believe that Lansing Mfg. Co. and later Altec Lansing obtained these parts from Magnavox, as the identical item was used in 1930s Magnavox drivers utilizing a 2" voice coil. I have a circa 1933 Lansing 15X pedestal base woofer that uses a more typical corrugated cloth spider. The basket casting of this driver does not have the raised bosses that slightly later Lansing 15s have, allowing the mounting of this spider with four screws. Nearly all of the Lansing and Altec field coil 15" drivers used this spider. When the permanent magnet 604 and 515 15" drivers debuted, a similar design 3" phenolic spider was used, and was eventually replaced by a corrugated cloth spider in the mid 1950s. In the 601, it appears that they mounted the spider to the stamped Utah basket and Altec motor structure using stand offs.

Aloha Steve

That is way cool!

Thanks for the picts and contributions.

Steve

:applaud: NICE FIND!!!:applaud:

Did you or your friend purchase this driver? I think the term "priceless" comes to mind.

I'm impressed!

Ron

Duaneage, I discussed the possibility of buying the 601 with the owner, but he was not interested in selling it. So, priceless is indeed the word for this driver. He has been looking for a mate for it without success, but wishes to hang on to this rare piece. I can't blame him one bit for this, and feel very fortunate that I was able to look it over and photograph it.

It would be fun to compare the sound of this driver with the 604s in their various incarnations, but the closest I am likely to come to this will be a replica I hope to build some day. I can imagine that the 601 would sound really good, based on my experience with the Lansing Iconic components, which were basically combined to create the 601. My guess is that the 601 would sound similar to the early 604, with the additional clarity and relaxed sound provided by field coil operation.

He shoulda taken your offer Steve.


The man obviously needs new shoes with enough material to cover his toes!!!!!!

Oldmics

Good point, oldmics. This vintage collecting hobby can leave one's pockets turned inside out. To own a 601 though, I wouldn't care if I had pants on or not!

Thanks for your report and photos. It's always nice to learn more and add all this to the documented Lansing history.

Since you are fond of the 15" co-ax, why not find a clean pair of Altec 604s and put them in ideal cabinets and tweak the crossovers to come up with "the best" 604 system? Many people really enjoy these, especially when they are set up to be optimal.

Tom

That driver on eBay would bring down the servers.

I hope that Steve can revisit the nice man with bad shoes and examine further that T-Rex of a driver to help design his own.

Christ, wish i could do something like that. Truly amazing to see something as evolutionary as that.