noooooooooooooo - temptation!!Originally Posted by bigyank
Here are a pair of these in Woodbridge, VA on the 'Bay (Heather you should go get a listen):
http://cgi.ebay.com/ws/eBayISAPI.dll...63#description
I also have to say that this was a very nicely written and authoritative read.
Yank
2ch: WiiM Pro; Topping E30 II DAC; Oppo, Acurus RL-11, Acurus A200, JBL Dynamics Project - Offline: L212-TwinStack, VonSchweikert VR-4
7: TIVO, Oppo BDP103D, B&K, 2pr UREI 809A, TF600, JBL B460
These were the best styled horn spkr - especially in RCA 60's tech blue
Inspiration for style of latest K2 ?
Interesting as they may be, I still think the market is funky right now ...
sale ended but reserve price was not met ...
Someone should go after them - they look amazing!
2ch: WiiM Pro; Topping E30 II DAC; Oppo, Acurus RL-11, Acurus A200, JBL Dynamics Project - Offline: L212-TwinStack, VonSchweikert VR-4
7: TIVO, Oppo BDP103D, B&K, 2pr UREI 809A, TF600, JBL B460
It was supposed to end on Saturday, so he ended it early, probably to get pics of the back, and the drivers (I even emailed to ask for some). I think a good part of the value in these will be if the original RCA drivers are in there. I don't think there's any shortage of buyers for them, as he is willing to ship them anywhere.
Yes, I wrote him and mentioned this thread and asked if he'd mind sharing the photos so we could post them in the thread for historical reference.
He's very friendly! I'd love to go have a listen but this weekend is swamped!
Maybe next weekend, if they are still around -
2ch: WiiM Pro; Topping E30 II DAC; Oppo, Acurus RL-11, Acurus A200, JBL Dynamics Project - Offline: L212-TwinStack, VonSchweikert VR-4
7: TIVO, Oppo BDP103D, B&K, 2pr UREI 809A, TF600, JBL B460
what is the purpose of the "quasi-spherical" depression near the woofer in the bass section?
I have a pair of Fostex H425 wood horns (shaped somewhat like Smith or Westlake styled in my 'rookie' estimation), that are constructed in much the same, if not an identical, manner...
The bump is a result of the radial design, a consequence of maintaining the exponential expansion of the area while allowing the side walls to flare out straight. If the side walls were bent to the right shape, the bump would go flat (as the Altec bass horn does.) If you could see the throat area of the high frequency horn you would see a similar 'bump' on the top and bottom walls, pinching down to a gap height that is narrower than the exit diameter of the driver, but then expanding up again as you near the throat. This is all to satisify the rules governing the expansion of the area - in the case of a sectoral horn it is the cylindrical surface area swept across the arc between the side walls that is to expand out exponentially (or at whatever rate you want). In a flat-front horn it is the cross-sectional area that is evaluated. (I've been reading books by Olson, and many others lately...neat stuff)
The modern product ?
http://www.oceanwayaudio.com/
http://www.zephyrn.com/news/pdf/OCEANWAYbrochure.pdf
Stéphane
Stephane that cabinet is the real thing, an experimental prototype built at RCA to A.J. May's specifications. In his forty year career at RCA, A.J. made hundreds of experiments like this and many thousands of response measurements. It appears to contain the LC-9 120 degree radial mid/high frequency horn as well as the small woofers.
I know the seller; he was a friend of A.J., and he has been nice enough to forward several boxes of A.J.'s lab notebooks and measurements to me.
Just offering up the original US version of the ebay link ...
http://cgi.ebay.com/ws/eBayISAPI.dll...m=180414214603
2ch: WiiM Pro; Topping E30 II DAC; Oppo, Acurus RL-11, Acurus A200, JBL Dynamics Project - Offline: L212-TwinStack, VonSchweikert VR-4
7: TIVO, Oppo BDP103D, B&K, 2pr UREI 809A, TF600, JBL B460
would these be those? -
http://cgi.ebay.com/ws/eBayISAPI.dll...mtSGyi2mU%253D
Last edited by tomt; 05-15-2011 at 04:07 PM. Reason: 11963
Those speakers are from A.J. May's estate, no doubt about it. When I visited A.J.'s home about nine years ago, his large basement workshop was loaded with stuff like this. If RCA was going to toss something out, A.J. would often bring it home instead. A.J. lived and breathed loudspeaker research, development and testing for his entire forty year career at RCA.
The ebay seller is not my friend as I thought, but another fellow who obtained some of A.J.'s materials from him or through him somehow. I hope it all finds it's way into appreciative hands.
To answer louped garouv's nearly two year old question about the bass horn flare... in a radial horn two sides are straight while the other two are curved. It is a hybrid horn design that combines the excellent directivity of the conical horn in the horizontal while achieving the low frequency loading of an exponential expansion with the curved sides. Keeping this exponential expansion in mind it can be seen that the straight sides expand so rapidly from the throat that the curved sides need to initially neck down in the vertical axis in order to maintain the desired overall exponential expansion of the cross section.
I realize this is an older thread, but I just saw the new HR4 info (looking through
the upcoming "T.H.E. Show" vendors...
and couldn't help but think Mr. Sides has had a serious long-term RCA jones going on...
Not only the LC-9A 'clone' (HR2), but now this mini-Ubangi-vibe looking thing:
http://oceanwayaudio.com/hr4/
Makes me wonder if a turn on the spinorama would support the jibba-jabba.
They look interesting, and I guess that's 90% of it.
Grumpy, almost every story that I have heard over the past twenty five years that mentioned RCA radial horn enclosures has involved Mr. Alan Sides in some way. As the story goes, he once had a storage facility under the Pacific Ocean Park pier in Venice, CA that had many of the MI-9462 double woofer "Ubangi" theatre bass bins stacked up. I am a bit miffed that in recent years he has chosen to market monitoring systems to recording studios that feature the radial horn technology while refusing to give credit to RCA and its engineers that made it all happen in the late 1940s to early 1950s. I can verify this as I am fortunate to have several boxes of vintage RCA documentation from the inventors of these radial horns and systems. I once had a long phone conversation with Mr. Sides and he seemed fully aware of the RCA contributions, which makes his continuing refusal to provide acknowledgement all the more perplexing.
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