Yes, if he doesn't mind please post the pictures.
Yes, if he doesn't mind please post the pictures.
sorry steve, i should have asked his permission first, as he doesnt want to reveal his finds just yet - fair enough as he went to a lot of trouble finding them. he has put me to thinking i should ask to look around the backstage area of our bingo hall, that used to be an odeon. never know might be something waiting to be discovered. there is a lot more interest in old cinema equipment now. i regret my granddad's disregard for the vintage equipment as it would have a lot of value today.
i kept some pictures of the gaumont 379, hope that's some interest.
Thanks for the pictures, pde2000. It is curious that in some of these European drivers we see many elements "borrowed" from the Lansing and Altec Lansing products, though sometimes in combinations that never occurred in the U.S. built gear. The Gaumont 379 uses the half roll surround type diaphragm of all Lansing compression drivers preceeding the Altec 288, which used a tangential surround. It also appears to use the threaded attachment to the horn of the early Lansings. The radial slit phasing plug is a close copy of the Lansing 285 of 1937/38. The Gaumont uses an interior ring permanent magnet though, which didn't appear here until the Altec 288 of 1945.
Here is a picture of a Lansing 285 with diaphragm removed. The phasing plug was originally plated, but had become corroded and bumpy, endangering the diaphragm. I removed the plating, revealing a beautiful brass machined phasing plug. Interested parties can read Dr. John Blackburn's U.S. Patent on this phasing plug here:
https://docs.google.com/viewer?url=patentimages.storage.googleapis.com/pdfs/US2183528.pdf
Sorry, but I tried and tried and could not load the image from my backup disc. As I recall, loading images into a post on this site used to be so simple even I could do it, but no more with the current vexing "file upload manager." Sheesh.
the permanent magnet in my copy was rather weak and I was able to pull the assembly apart to remove the phase plug and get a closer look, but didn't have the camera with me at the time (I was at work) when I tried doing the same with the we2090 the plate snapped shut and took the tip off my colleagues finger so I gave up (one hell of a magnet). also the gaumonts voice coil was just round enamel wire and the output sounded weak compared to the we2090. the round threaded throat fits the vitavox horns and there is a demand for the 379's because of rarity. give me an altec 288 anyday.
regards, paul
It's been stated ( quite a few times here at LHF, as well as at other web-sites ) that one should never break the magnetic circuit ( of the typical alnico assembly ) because once broken ( as example, by removing the top-plate ) the whole assembly then needs to be re-magnetized .
Just Saying ( & passing it on )
thanks for the advice earl. I wont do it again. even being remagnetised wouldn't make the gaumont magnet powerful, but replacting with a field coil would work. making a ribbon voice coil isn't out of the question, or rather transplanting one if they fit, but I sold the gaumont and the bth. using the 288c satisfies my needs, in some ways it exceeds them. its playing the cheap diamond suspension diaphragm (16r) and is a very good match to the 2090 with the gpa 16r. the 2090 has a much heavier pressure cap which doesn't come with a felt damper or a rubber gasket, but I have put a thick felt disc in. the 288c seems a bit flimsy in comparison to the 2090, the terminals particularly. western electric London must have been contemporaries of altec before Litton industries got it. british audio industries all seem to be connected back then, so collaboration rather than competition lead to innovation. western electric paid their staff well too, because pop wanted to work for decca to develop radar when he was demobbed but they couldn't match we's salary.
hopefully these will attach
. its getting complicated posting images. the first is a repaired xo (the others are inside the cabinets), the next two are the 555 to 805 adaptor, which I only have one of unfortunately. then the 288c, compared to the we2090.
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