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More RCA Restoration pix

75.171.240.76
Posted on August 15, 2013 at 20:39:55
gilmorneau
Audiophile

Posts: 288
Location: Colorado
Joined: August 10, 2004



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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RE: More RCA Restoration pix, posted on August 15, 2013 at 20:40:55
gilmorneau
Audiophile

Posts: 288
Location: Colorado
Joined: August 10, 2004



the 64-A cabinet.....

 

RE: More RCA Restoration pix, posted on August 15, 2013 at 20:41:42
gilmorneau
Audiophile

Posts: 288
Location: Colorado
Joined: August 10, 2004



and a group shot....

 

RCA Bracework, posted on August 15, 2013 at 21:20:32
moray james
Manufacturer

Posts: 1599
Location: Calgary on the Bow
Joined: May 19, 2002
 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

 

RE: More RCA Restoration pix, posted on August 15, 2013 at 22:20:25
Steve Schell
Manufacturer

Posts: 1440
Location: So. California
Joined: December 16, 2001
 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.

 

RE: More RCA Restoration pix, posted on August 16, 2013 at 06:15:10
Kloss
 Wonderful wonderful!!

 

RE: More RCA Restoration pix, posted on August 16, 2013 at 06:16:13
Kloss
 Oh so very nice.

 

RE: More RCA Restoration pix, posted on August 16, 2013 at 06:17:51
Kloss
 Such beauty brings tears 2 my eyes.

 

Green With Envy!, posted on August 16, 2013 at 08:36:43
amandarae
Audiophile

Posts: 2591
Location: So.Cal
Joined: November 30, 2004
 Marvelous work! Beautiful cabs!

Abe

 

Thanks and a Shameless Appeal....., posted on August 16, 2013 at 20:26:42
gilmorneau
Audiophile

Posts: 288
Location: Colorado
Joined: August 10, 2004
 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.

 

RE: RCA Bracework, posted on August 16, 2013 at 20:31:14
gilmorneau
Audiophile

Posts: 288
Location: Colorado
Joined: August 10, 2004
 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.

 

vintage speakers... yea baby, posted on August 17, 2013 at 05:07:17
lokie
Audiophile

Posts: 1989
Location: Georgia, USA
Joined: January 28, 2003
 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?

 

RE: vintage speakers... yea baby, posted on August 17, 2013 at 19:52:51
gilmorneau
Audiophile

Posts: 288
Location: Colorado
Joined: August 10, 2004
 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.

 

RE: vintage speakers... yea baby, posted on August 18, 2013 at 07:31:12
Grinnell
Audiophile

Posts: 709
Location: Front Range
Joined: December 23, 2007
 Where are you in Colorado? I'm up in Northern CO and would love to hear those when your done. :)

 

RE: vintage speakers... yea baby, posted on August 18, 2013 at 09:54:46
gilmorneau
Audiophile

Posts: 288
Location: Colorado
Joined: August 10, 2004
 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.

 

RE: vintage speakers... yea baby, posted on August 19, 2013 at 15:56:34
Grinnell
Audiophile

Posts: 709
Location: Front Range
Joined: December 23, 2007
 ok they are sweet

 

Vintage RCA 64b clones, posted on August 31, 2013 at 17:13:17
langleycello
Audiophile

Posts: 31
Location: Melbourne
Joined: May 13, 2002




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.

 

RE: RCA Bracework, posted on August 26, 2014 at 05:42:47
gmsiryk
Audiophile

Posts: 1
Joined: August 26, 2014
 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.

 

RE: Vintage RCA 64b clones, posted on August 2, 2019 at 04:21:09
goldjazz
Audiophile

Posts: 32
Joined: January 21, 2015
 Hi I also have one of these A.B.C clones of the RCA 64-ax or 64-b :)

 

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