RCA ; LC-9A pics

[Earl K]

Hi

- Here are some pics of RCAs' answer to Altecs', A7 .

:)

[Earl K]

A couple more

[spkrman57]

I have not seen any of these in person, only advertising pics.

Cool vintage speakers!

Ron

[Earl K]

Cool vintage speakers!

- Yep, pretty cool . That flowing throat section of the lowmid horn would be a real brute to reproduce .

- I don't know what quantity these were made in / they are scarce . Steve Schell would likely know .

- Here are some pics of a likely candidate for the role of the compression driver. These are le175s' OEMed for RCA by JBL .
- I don't know anything about the 15" woofers' make or model # .

<> :)

[Steve Schell]

Earl posted these images in response to a request over on the Audio Asylum High Efficiency Speakers forum... what a guy.

The story of the RCA LC-9A is an interesting one, at least to RCA buffs. This model was developed by Mr. A.J. May, who had a storied career in speaker engineering at RCA from 1943 until the early 1980s. It was RCA's attempt to compete with Altec's A7, and to improve on what RCA felt were the A7's shortcomings, most notably the lack of directivity control through the crossover region.

The LC-9A used 120 degree radial horn flares for both high and low frequency sections, and achieved a very uniform pattern over this angle. Due to the high construction costs of the cabinet and cast horn flares it was not cost competitive with the A7 and sold in very small numbers. RCA was really beginning to unravel by the time the LC-9A was introduced, and it is probably safe to say that it did not receive the marketing effort that the design deserved. I have heard a pair of them with original drivers, and they really are marvelous speakers with a captivating sound.

The LC-9A was a bass reflex design, with three large ports on the lower front faces of the cabinet. Mr. May had intended to fit passive radiators to these openings. As he told me the story, his managers heard the design at an early stage, found the performance to be "good enough", proclaimed the design finished, and reassigned A.J. to other tasks. Ah, the tribulations of working for a large corporation!

No one is certain how many LC-9As were built and sold, but it may have been only two or three hundred. The people I know who own them hold them in high esteem and wouldn't part with them for anything.

[Steve Schell]

Here's a picture of Mr. A.J. May, taken in the fall of 2002. A.J. died in early 2004. He was a sweet, kindly man, the sort you cannot help but like immediately. He designed the LC-9A, the MI-9462 (Ubangi) bass enclosure, the majority of RCA's postwar radial horn products, and much more. He was very humble though, always attempting to assign credit to others. He was John Volkmann's (inventor of the radial horn) understudy in the early years, and helped him to maintain an ever-changing experimental sound system at Radio City Music Hall. He also worked for a time at Princeton with Harry Olson. He frequently said "I was their chief measurer", preferring to be regarded as an assistant rather than the innovator he truly was. He told me in 2002, on the day the picture was taken: "It has been a very interesting life."

[Titanium Dome]

Interesting read and important bio bit on A. J. May, Steve. Thank you.

[Steve Gonzales]

I really enjoyed this. Thanks Earl and Steve.

[Steve Schell]

Here is JBL's sales model drawing for the small format driver they provided to RCA for the LC-9A.

[Earl K]

Hi

Steve, that's a great picture of Mr. May .

Thanks ! for posting that / as well as all your text contributions .

regards <. Earl K

[RacerXtreme]

Very cool story......... thanks for the pics.

Ever had the opportunity to do a side by side comparison ?

Which pair of speakers sounded better - Altec A7's or these RCA's ?

[Steve Schell]

RacerXtreme, I've never heard the two speakers side by side. In fact I've only listened carefully to LC-9As once as a stereo pair. I would have to give the nod to the RCA though.

The bass sounds extremely smooth and punchy; this is characteristic of the radial horn combination cabinets, including the larger RCA theatre models. The high frequency performance is unique in my experience, though better suited to some situations than others. The radial horn has a 120 degree horizontal dispersion pattern, and this is not just on paper. I carefully listened on and off axis, and at 60 degrees off axis (virtually beside the cabinet) the highs sound nearly identical to the sound on axis- unbelievable! The highs and lows blend together very well both on and way off axis, a very different experience from the beamy highs of the A7. Of course I tend to get all wiggly in the presence of rare speakers, so my exhuberence should probably be factored in.

Bill Woods measured the LC-9As I listened to, and has published the on axis curve. Check out the smoothness of the highs. You can find his post on this Audio Asylum thread and view the response curve in his picture gallery:

http://www.audioasylum.com/scripts/t.pl?f=hug&m=110255

[Titanium Dome]

A lot of times I find these vintage threads leave a dusty, dry, choking coating in my throat, so I normally don't post in them or read beyond the first post or two.

However, I find this thread to be quite interesting and informative. You guys have done a good job to make this more than a mere requiem for a pile of rusted metal and shredded cloth. I'd actually like to see and hear these babies. You've both inspired me. Thanks!

[thetubeguy1954]

I've recently obtained a pair of these RCA enclosures and have decided to do a complete DIY restoration on these myself, as I am able to, but with my back being what it is that will be a long sloooowww process.

1) Stripping & removing all the white paint.
2) I'll use wood filler to fill all the uneven edges & sand as needed.
3) Tighten up everything that can be manuelly tightened.
4) Fill any remaining open seams & sand again!
5) Prime all wood & fiberglass.
6) Paint the upper & lower horns semi-gloss black.
7) Paint all remaining surfaces that aren't black, burgundy. That color combo will match the Mastersound amp and the stand it sits on! Then all 3 pieces will be black & burgundy. (Basically I'm taking the original color scheme of black & blue and making it black & burgundy)

My friend Paul Butterfield has even offered me some beautiful burgundy grill cloth to cover the area under the bass horn. I'll take photos of the process as it happens for prosperity...

The possible correction? I believe it's possible that the enclosures might not have been refered to as LC9A. The reason for my belief is this, while looking at the back of the RCA enclosures one of them said MI-11419 I know this is what RCA relabled the JBL LE175 when used in the upper horn. However below that it said "enclosure for the LC9A" ! I then remembered that RCA made a fullrange 15" speaker called the LC1A. So I now believe the enclosures aren't called LC9A but rather that's the designation of the woofers that went in them!

Afterall consider:

LC1A is there 15" fullrange
LC9A seems to follow RCA's naming convention for 15" woofers.

Of course I may be incorrect, but it's the only way the words "Enclosure for LC9A" seems to make sense. I've attached a photo of my pair of RCAs and will take some photos of the words on the back as well.

Thetubeguy1954

[Steve Schell]

Congratulations on scoring this very rare pair of cabinets. You've got some heavy duty stripping and sanding ahead of you, but the final results should be beautiful in your chosen color combination.

I believe that in RCA nomenclature "LC" once stood for loudspeaker cabinet. Somehow it got scrambled up in the marketing of Harry Olson's Duo-cone driver MI-11411 and the various cabinets it was used with, until a later version of the Duo-cone driver was labeled LC-1A. As far as I know the terms LC-9 and LC-9A were only used to describe the complete two way speaker system.

The RCA literature describes both LC-9 and LC-9A models of the two way speaker; I'm not sure what the differences are.

[Audioconsultant]

Back when I worked for RCA Records in NYC I picked up 3 LC9a, and then picked up 3 more of just the empty cabinets when RCA dumped the remaining inventory from their warehouse in Camden NJ. Two of the new cabinets got built up (don't remember what drivers I used) and sold to the film department at New York Institute of Technology on Long Island.

Only one of my systems came with the passive crossover, but if I recall correctly it was 3rd order for both high and low pass.

The original woofer was made by RCA themselves in Camden, and had a very large ceramic magnet. Community Light and Sound (now Community Loudspeakers) bought the magnetizer used for the woofer magnets from RCA and used it for the magnets of their M4 mid range driver (which may just be the most efficient driver ever made).

My favorite way to use these speakers for sound reinforcement was stacking two with the top box upside down. This placed the HF horns right next to each other, the LF horns further apart, and the LF ports even further apart. The result was significantly increased directivity vertically, but no change in the horizontal plane. I drove these with McIntosh MC40 for the highs, and a MC2120 for the lows, and a custom modified UREI crossover.

Unfortunately two of my LC9a were lost in a move, but I still have and use the other two.

To my ears the weakest link was the HF drivers. I replaced the original JBL made, RCA labeled drivers first with the larger magnet JBL drivers. Later these were replaced with Emilar EA175 drivers. The Emilar drivers on the RCA HF horns were dead flat up to 12 kHz, but got ragged above 12 kHz.

Tom Danley suggested I replace the HF drivers with BMS 4550 and the original RCA LF drivers with JBL 2226H. I have a pair of 2226H but they need to be reconed, so I used a pair of JBL 2225H instead. The results have been wonderful. They have never sounded better, and the highs are the best they have ever been. Current amp configuration is a Crown Macro-Tech 1200 for the HF and a Crown Macro-Tech 2400 for the LF, with a Peavey original X-Frame serving as the crossover and (minimal) EQ.

I drag these out at least once or twice a year for outdoor sound reinforcement events and get complements on the sound. Yes the drivers have been updated, but these are still the same 1950 vintage loudspeakers still going strong.

[glen]

Unfortunately two of my LC9a were lost in a move, but I still have and use the other two.
Holy Cow!
Must've taken some real determination to lose those giant cabinets.
Don't use those movers again!


To my ears the weakest link was the HF drivers. I replaced the original JBL made, RCA labeled drivers first with the larger magnet JBL drivers. Later these were replaced with Emilar EA175 drivers. The Emilar drivers on the RCA HF horns were dead flat up to 12 kHz, but got ragged above 12 kHz.

Interesting that you felt the 175 was inadequate.

I recently saw a 275 on ebay that had a rectangular inset on the back to receive a missing nameplate. Made me wonder if a version of the 275 might have been made for RCA since they used JBL drivers AND used a rectangular nameplate.

Thanks for your info!

[louped garouv]

I drag these out at least once or twice a year for outdoor sound reinforcement events and get complements on the sound. Yes the drivers have been updated, but these are still the same 1950 vintage loudspeakers still going strong.


Are these generally public events?

are they near Denver?

how neat,

and thanks to all for sharing info about these units...

[Audioconsultant]

louped garouv (http://www.audioheritage.org/vbulletin/member.php?u=792) -

"Are these generally public events?

are they near Denver?"

Every April for the last 4 years I have done the sound for the Homeschool rally on the West steps of the state capitol in Denver. It is usually Noon on a Friday. We have had crowds of up to 3000 depending on the weather.

The LC-9a are the main speakers placed up high on either side of the West steps, and a pair of JBL 4331a studio monitors are the side fill speakers (there is over a 180 degree arc to cover). An EAW CP621 stuck on a pole mount is used for near center fill. There is a delay system running on generator to cover the green running down the hill to the West. That uses four EV Zx5 on poles to cover the area. Audio gets to the delay system via a Lectrosonics Digital Hybrid wireless link.

I usually also do a few events in the Longmont / Boulder area, but this year did not.

[Audioconsultant]

glen (http://www.audioheritage.org/vbulletin/member.php?u=182) -

"Interesting that you felt the 175 was inadequate."

The EA175 were much nicer than either the RCA/JBL or the larger JBL I had used in the LC9a before the Emilar. However next to the BMS 4550 they did not sound anywhere near as nice :>)

[Audioconsultant]

Holy Cow!
Must've taken some real determination to lose those giant cabinets.
Don't use those movers again!

That is not as bad as when a shipping company "lost" four Community CB594 (43" x 53" x 68") between the factory and NYC.

[00Robin]

Here's a picture of Mr. A.J. May, taken in the fall of 2002. A.J. died in early 2004. He was a sweet, kindly man, the sort you cannot help but like immediately. He designed the LC-9A, the MI-9462 (Ubangi) bass enclosure, the majority of RCA's postwar radial horn products, and much more. He was very humble though, always attempting to assign credit to others. He was John Volkmann's (inventor of the radial horn) understudy in the early years, and helped him to maintain an ever-changing experimental sound system at Radio City Music Hall. He also worked for a time at Princeton with Harry Olson. He frequently said "I was their chief measurer", preferring to be regarded as an assistant rather than the innovator he truly was. He told me in 2002, on the day the picture was taken: "It has been a very interesting life."

I wanted the attachment but I don't know how...
I would loved to have given him a kiss and a real tight hug.

[RKLee]

An audio newbie here, I didn't catch when the RCA LC-9s were generally commerially available, approximately what were the years.


I wanted the attachment but I don't know how...
I would loved to have given him a kiss and a real tight hug.That is the problem with getting old, all the people that you admired are going away.

[Earl K]

snip,,,,,, I didn't catch when the RCA LC-9s were generally commercially available, approximately what were the years?

- I can't give you much of a definative answer to your question / Steve Schell should have a much better handle on it .

- You can get an idea about when RCA started to seriously develop this product ( ie; @ 1965 ) by assuming that's when they contracted JBL to start OEMing a rebadged le175 as the RCA MI-11419 for use in their LC-9 . ( see the "sales drawing" that Steve Schell posted above ) .


:)

[Audioconsultant]

An audio newbie here, I didn't catch when the RCA LC-9s were generally commerially available, approximately what were the years.

You can now buy brand new RCA LC-9a in a slick gloss black finish, with an added subwoofer they sit on. I am at the AES Convention in NYC, and Ocean Way Audio has just introduced their HR-2 studio monitors "designed by Allen Sides". While they no where say this, these are nothing more than copies of the LC-9a (plus a sub). They will install a triamped pair in your studio for a mere $34,000.00.

[4313B]

Welcome to the forum Audioconsultant. :)

[thetubeguy1954]

- Yep, pretty cool . That flowing throat section of the lowmid horn would be a real brute to reproduce .

- I don't know what quantity these were made in / they are scarce . Steve Schell would likely know .

- Here are some pics of a likely candidate for the role of the compression driver. These are le175s' OEMed for RCA by JBL .
- I don't know anything about the 15" woofers' make or model # .

<> :)

I've been told that the number of LC9As made was between 100-300 pairs! That makes them a fairly rare item to obtain. To provide the information Steve didn't have the about the LC9A woofers their model # was MI-11421.

As I previously stated in this thread I have 2 LC9A cabinets ---{they were completely white when I received them as you can see in the previous photo but were painted via paintbrush, so there were a lot of drips and paintbrush lines}--- I've since removed about 99% of all the white paint from both cabinets.

I've been removing the paint and sanding them ---{for 2 years now}--- but, sadly being disabled it takes me forever to do anything to these enclosures. Plus since obtaining the RCA LC9As I was involved in a terrible car accident which only exasperated my disability. I'm afraid I bit off more than I can chew with this DIY project. Thus with a heavy heart I must let them go.

At present I have ---{and these are all exceedinly rare}--- 2 working pairs (4 drivers total) of the original RCA MI-11421 woofers ---{one has been reconed thus looks differently but the other 3 are completely stock}--- I also have 3 RCA MI-11419 compression drivers ---{1 doesn't work but I assume it can be rebuilt, the other 2 work perfectly and still have their red seals intact}--- Plus I have 1 working original crossover. These parts are extremely rare and difficult to find. In the 2 years I've been looking I've seen 1 MI-11421 woofer on eBay for $450 and I've yet to see the MI-11419 anywhere for sale!

Essentially I'm just 1 working crossover away from having 2 completely original, working, stock RCA LC9A speakers that health & finances are compelling me to sell. I thought I'd offer them first right here because I believe the people here appreciate their rarity. I'd like someone to get a good deal but I'm not willing to give them away either. I'm AM willing to entertain offers @ [email protected]

Of course being that I'm disabled I cannot bring these anywhere to have them shipped so the buyer would have to arrange to have them picked up and shipped at their expense. I'll happily make things as easy for the shipper as I possibly can. I'm also definitely willing to pack up all the drivers for safe shipping. So "if" you're interested in purchasing a piece of audio history and obtaining excellent sonics at the same time, please shoot me an email with your offer. The first person who hits the number I have in mind will get them.

Of course I'm willing to provide photos of any of the LC9A's components cabinets, compression drivers, woofers and crossover from any angle you might wish and "if" it starts to appear a transaction might transpire I'll provide my phone # at that time.

Thetubeguy1954

[louped garouv]

http://homepage.mac.com/ikecarumba/PhotoAlbum21.html


found a picture page on the RCA driver...


i am making a calendar mark now to make sure i don't miss the home school rally on the Denver capitol steps again next year....
:banghead:


I read somewhere that there is a field coil version of the LC1A driver....

anyone ever see one in real life?

thoughts?

[stephane RAME]

RCA Museum

http://www.oswaldsmillaudio.com/rcamuseum.html

http://www.oswaldsmillaudio.com/rcaarchive.html

[bigyank]

Here are a pair of these in Woodbridge, VA on the 'Bay (Heather you should go get a listen :D):

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=260452587263#description

I also have to say that this was a very nicely written and authoritative read.

Yank

[hjames]

Here are a pair of these in Woodbridge, VA on the 'Bay (Heather you should go get a listen :D):

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=260452587263#description

I also have to say that this was a very nicely written and authoritative read.

Yank

noooooooooooooo - temptation!!

[Horn Savant]

These were the best styled horn spkr - especially in RCA 60's tech blue
Inspiration for style of latest K2 ?

[hjames]

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!

[tomee]

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!

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.

[hjames]

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 - :bouncy:

[louped garouv]

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...

[tomee]

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 ;))

[stephane RAME]

The modern product ?

http://www.oceanwayaudio.com/
http://www.zephyrn.com/news/pdf/OCEANWAYbrochure.pdf

Stéphane

[stephane RAME]

http://cgi.ebay.fr/RCA-UBANGI-SPEAKER-CABINET-LC9-PROTOTYPE-5-8-RCA-SPKRS_W0QQitemZ180414214603QQcmdZViewItemQQptZVint age_Electronics_R2?hash=item2a018671cb

Stéphane

[Steve Schell]

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.

[hjames]

Just offering up the original US version of the ebay link ...
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=180414214603

[tomt]

http://cgi.ebay.fr/RCA-UBANGI-SPEAKER-CABINET-LC9-PROTOTYPE-5-8-RCA-SPKRS_W0QQitemZ180414214603QQcmdZViewItemQQptZVint age_Electronics_R2?hash=item2a018671cb

Stéphane

would these be those? -

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&_trksid=p4340.l2557&hash=item2a0e803d5e&item=180631911774&nma=true&pt=Vintage_Electronics_R2&rt=nc&si=DugEMOcCXO1wN5Ey2XmtSGyi2mU%253D


http://img834.imageshack.us/img834/6679/45779451.jpg (http://imageshack.us/photo/my-images/834/45779451.jpg/)


http://img822.imageshack.us/img822/8648/80417273.jpg (http://imageshack.us/photo/my-images/822/80417273.jpg/)

http://img806.imageshack.us/img806/5740/61197501.jpg (http://imageshack.us/photo/my-images/806/61197501.jpg/)

http://img717.imageshack.us/img717/719/zzzkd.jpg (http://imageshack.us/photo/my-images/717/zzzkd.jpg/)

http://img16.imageshack.us/img16/5248/zzzzui.jpg (http://imageshack.us/photo/my-images/16/zzzzui.jpg/)

http://img560.imageshack.us/img560/7868/zzzzzzw.jpg (http://imageshack.us/photo/my-images/560/zzzzzzw.jpg/)

[Steve Schell]

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.

[grumpy]

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.

[Steve Schell]

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.

[grumpy]

Indeed.