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Sound Reinforcement - Forums for Live Sound Professionals - Your Displayed Name Must Be Your Real Full Name To Post In The Live Sound Forums => HistoryOfConcertSound.org => Topic started by: GenePink on May 13, 2014, 02:40:11 AM

Title: Really old bins, RCA MI-6264
Post by: GenePink on May 13, 2014, 02:40:11 AM
I thought this part of the board was about old stuff, most of the postings here, I have owned, or at least heard and lusted after "back then".

I got one for y'all, the cut sheet from 1946. Anybody got a spare 3" ID VC that will fit this?
Title: Re: Really old bins, RCA MI-6264
Post by: Joseph D. Macry on May 13, 2014, 10:02:19 AM
224 lbs??!!
Title: Re: Really old bins, RCA MI-6264
Post by: Tim Weaver on May 13, 2014, 02:32:11 PM
I came across a set of RCA LC9A's years ago. The cabinets were rotten, but the drivers were still good. I passed them on to this guy and he is evidently loving them!

http://www.diyaudio.com/forums/multi-way/84971-rca-lc9as-crossovers.html
Title: Re: Really old bins, RCA MI-6264
Post by: Mike Smith on May 17, 2014, 12:00:38 AM
I thought this part of the board was about old stuff, most of the postings here, I have owned, or at least heard and lusted after "back then".

I got one for y'all, the cut sheet from 1946. Anybody got a spare 3" ID VC that will fit this?

Somebody get on the teletype and ask RCA for the DSP settings.
Title: Re: Really old bins, RCA MI-6264
Post by: GenePink on May 17, 2014, 05:34:06 AM
I came across a set of RCA LC9A's years ago. The cabinets were rotten, but the drivers were still good. I passed them on to this guy and he is evidently loving them!

I get that, nothing like the feeling of bringing some obscure rare classic beasts back to live and work again, they deserve it in their waning years.

And Joesph, you have a point, 224 lbs does seem a bit light, maybe I will throw a few cinder blocks in them so they weigh as much as a Meyer MSL-3. Coincidentally, these RCAs are parked right now about 10 foot from four MSL-3s.

I am searching for any info on these bins, as the drivers don't match up with the 1946 cut sheet, and I have no idea if they are original, later upgrades, of from an earlier build. So far the consensus is that these bins were the first run built specifically for the 1939 Worlds Fair and they actually were first used there. Still hearsay at this point.

The 15s are close, but the sheet shows a MI-9448, but these "speaker mechanisms" are  MI-9446. And they work fine, with their outer clamping ring and brass ring inner suspension. No glue, the cone can be removed and replaced by unscrewing 12 screws.

The 1.5" drivers are supposed to be MI-12432 with phenolic diaphragms, but these are MI-9446 with aluminum diaphragms, same part number as the 15s.

Huh? Same number??? WTF. But that is what it says.

So, I have no idea what I have, and internet searches over the past month have yielded very little info. I guess they didn't have the internet back in '39.

On a related note, Does anyone know of a diaphragm that may fit? I fixed the one I have and it now works fine, but making another one from scratch may be a just a bit beyond my skillset. The VC former measures exactly 3.000" I.D., other dimensions available on request if anyone has a possible goesinto candidate.

First I looked at my stash of Altec Lansing 288 diaphragms, but it turns out they are only about 2.8-something" VC, so I tried a Nexo diaphragm from the 1.5" Alphas, really close, similar dome radiuses, but still about 30 thou off.

Any other ideas for something that I can kludge in there with a 3" ID VC? I'd hate to redrill and throw a pair of Altec 288s drivers at the problem, but it would be the easy way out. These bins are just standing up and begging to be fully restored to original every time I walk by and gaze at them. I figure about 60 hours of time, 1.5 gallons of Bondo, and a gallon of "machine grey" industrial enamel ought to do it. And of course, one more diaphragm.

Thanks for any help with this,

Gene Pink

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