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I have been away from my projects for a while, but have recently made some progress. Here's a couple pictures of the LC-1A's and 64-A's in primer. Finally picked up the two tone Umber Gray paint today, and should get them sprayed next weekend!
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Fantastic project. Please, please keep sending pictures as you progress.
What band width are you expecting?
Regarding the RCA model number MI-4466... are those re-conable?
The horn flare rate is around 40Hz, I believe, so reasonable bass. I'm expecting maybe a wee bit more than my Lowther Acousta's in that regard. High end FR will be more driver dependent. I have some old Ticonal Norelco's I'm going to try that should get me up to at least 12-15kHz. Good enough.
As for it being possible to re-cone an MI-4466, yea, sure, that can be done. It's not even that difficult, owing to the design of the driver. But actually finding the drivers (in order to recone them) is near impossible. Further, the chances of finding replacement cones are just a whisper above zero. I'm aware of exactly one MI-4466 in the known universe, and it's not for sale. They're really that rare.
Where are you in Colorado? I'm up in Northern CO and would love to hear those when your done. :)
I'm in Boulder. Keep an eye on the forum, and shoot me an e-mail when you see me post photos of the finished speakers.
ok they are sweet
I have found this thread on RCA speakers fascinating and it inspired me to reinstate an Australian 'clone' of the RCA 64b into the lounge room. The pictured unit uses an RCA SL8 and sounds great with a remarkably transparent bass response. Alas, the upper / mid is not brilliant and very directional with the whizzer cone, and I have supplemented a super tweet to add a bit of extension.
I actually have two more of these under the house ( they were used as monitor speakers in transmitter halls and studios by our national broadcaster) and while recreating the internal cabinet geometry exactly as the 64B, they used generic Rola 8" drivers - nothing as remarkable as the RCA equivalents with the diffusion veins etc.
My thought is to explore some of the smaller speakers such as the FE108EZ which get good press. Some years back I did try some AN Super 8s with the other pair, but the magnet is too wide for the internal slot and I didn't really succeed making an extender board ( without compromising the cosmetics). Anyhow, they sounded too 'forward' / bright in this configuration.
Any thoughts re suitable 'modern' full range drivers would be appreciated.
Hi I also have one of these A.B.C clones of the RCA 64-ax or 64-b :)
Thanks for all the kind words. I'm really starting to get excited about these. Paint is 'on' for next weekend. More pics when that's all done.
And here's the shameless appeal: I still haven't had any luck finding the correct, original type drivers for these cabinets. RCA model number MI-4466 is the one. Anybody? Any condition. Any location. Any time.
I'd consider the later model MI-4411 (field coil) or MI-4410 (permanent magnet), but my first choice remains the MI-4466.
Meanwhile, I have several different full range 8 inch speakers here that I'll give a try. I have it on good authority that the originals aren't the only thing that sound really good in these brilliantly designed cabinets.
Marvelous work! Beautiful cabs!
Abe
Wonderful wonderful!!
Fantastic work gilmorneau! The LC-1A cabinets are quite rare, due in part to their original construction utilizing non-waterproof glues... this from a retired RCA engineer who would know.
The 64A cabinets are super rare, the original embodiment of Olson and Massa's full-out 1930s effort at a wide bandwidth compact monitor speaker. The driver used a powerful field coil motor and ingenious dual voice coil drive for the single 8" cone speaker. Dispersion was achieved (at least for the 64B... not sure about the 64A) with a metal diffusor. These devices are described in these patents:
http://www.google.com/patents/US2102212?printsec=drawing&dq=2102212&ei=27INUt62HITCywHI7oAw#v=onepage&q=2102212&f=false
http://www.google.com/patents/US2007748?printsec=drawing&dq=2007748&ei=F7MNUvGCBaSbygGD04Aw#v=onepage&q=2007748&f=false
There is also a patent for the rear loaded horn, though I cannot find it at the moment. The cabinet for the 64A and 64B is an ingenious folded rear loaded horn, of 40Hz. or lower flare constant and around 9' length. Attenuation for the back horn output was achieved through restrictions to balance the direct radiator output. They most often hung from the ceiling in radio station control rooms, providing supreme quality reproduction for the era.
the 64-A cabinet.....
Oh so very nice.
and a group shot....
Such beauty brings tears 2 my eyes.
That's a solid looking cabinet and how every DIY builder should do the job. Makes me shake my head every time I see an empty hollow of a six sided box not a brace in sight. Look forward to seeing more pictures when they are all done and installed. lovely looking work. Best regards Moray James.
moray james
Not just braces--it's a rear loaded horn. Plans used to be online, though I can't find them anymore. If anyone wants to try and build these, I have copies. Not for the faint of heart, however. I have over 100 hours just into the restoration.
Hello. I live in Ukraine. Really want to build cabinets RCA 64-A (http://images.audioasylum.com/usr/y2012/02/55769/RCA_64-A_speaker_page_small.jpg). You wrote that you can send the drawing. If possible, please send me an email: gmsiryk@gmail.com
Sincerely, Nicholas
P.S. Sorry for my English, I write through the translator.
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