Strange RCA speakers...

[1blueheron]

I picked up this set of old RCA speakers a few days ago for a couple bucks.  Bought them mostly for the cool retro grill cloth and solid wood cabinets.  Opened them up and saw a strange wiring config.  Anyone know what this is all about.  Guessing they are holdover from the quadraphonic era or some such thing.  Supposed to provide "Panoramic sound"  Can't quite figure out the 3 wire hookup deal or the transformer.  doesn;t resemble a typical crossover network as best I can tell...   1960's vintage.  Thought I could make a cool little practice combo out of the cabinets.  There is a pair.

[jjasilli]

These boxes look to be from a PA system which had a number of speakers throughout a building or auditorium.  The amp's OT would have a line voltage out to the speakers, with a nominal voltage rating, usually either 25V or 70V.  This prevents the impedance of the many speakers to combine and mismatch the OT's output impedance. 


Each speaker enclosure would have a line matching tranny to convert the incoming "line voltage" to the impedance of the enclosure.  That's the likely purpose of the tranny in your enclosure.


The caps are likely a crossover network to direct the proper range of frequencies to the "woofer" and to the tweeter in each enclosure.

[sluckey]

I only see two wires coming out of that "transformer". That would make it an inductor. I believe it's just part of the crossover network.

Post a closeup pic of that label on the back so we can read the writing.

Regardless, these ain't rated for guitar duty. You'll probably destroy them PDQ if you connect them to a guitar amp and play above a whisper.

[shooter]

here's a link for model SS-6, although I think something's off, they don't appear to be 40W capable 

http://www.sonance.com/assets/media/files/downloads/SS4_SS6Manual_Final2.pdf

[sluckey]

That pdf is not for these RCA speakers.

[shooter]

ya I went back n figured that out, all I found was a seller that said they sounded great 

[jjasilli]

Looks like sluckey is right.  Looks like these are RCA SS-6: Though they look like PA speakers, they are "hi-fi" speakers".  Here's some other photo's.  It does seem that that the tranny-like thing is an inductor.

[1blueheron]

They were supposed to match up with RCA's Hi-Fi consoles back in 1960-1962.  These were "extension speakers".  I guess that was the 1960 version of today's surround sound. 

If that is a crossover network, it is very strange one.  Never saw a crossover using large caps on the low freq. driver and a coil on the high freq.  Seems backwards.  Will take a better picture tonight of the inside and post it up.  The wire leads are 3 wire rather than 2 which is the real puzzler as well.

[jjasilli]

Agreed.  But since they're extension speakers, maybe the filters are for midrange and tweeter?

[shooter]

think JJ's correct, the bass speaker was probably in the console.  bust out your jbl and an amp

[1blueheron]

Here's the Schematic.  Strange 3 wire factory supplied hookup.  Still don't completely get the purpose of the inductor as wired. Looks like the caps are just low frequency filters.

[jjasilli]

Yes, weird.  It seems that our info is incomplete.  The photo shows that the input wire is 3-stranded: it appears that one wire corresponds to your Red, middle to your Green, last to your Purple.  The Purple wire is to be jumpered on the screw terminals, for a purpose that's not clear to me.  The instructions on the Label are rather terse.  Seems to be some type of unique, proprietary extension speaker system that's hard to understand without knowing the source wiring.

[Ritchie200]

Interesting explanation of inductors in crossovers if nothing else just to see his collection of stereo stuff!!!

Jim

[jjasilli]

  One of the striking things in the video is how much volume drops off along with the filtering of frequency.  Given that ea measly 3dB requires 2X the amp output in watts, this seems to argue for active crossovers.  However, my 100W mono bloc tube amps > passive crossovers are loud enough.  So I haven't gone active.

[shooter]

 
Mr 200s comment about seeing the gear, and jjs 3db comment fired a synapsis to look into the voice of the theater cross over, which got me here;
https://www.soundandvision.com/content/living-legend-altec-lansings-%E2%80%98voice-theatre%E2%80%99
at which point I just surrendered

[sluckey]

Yes, weird.  It seems that our info is incomplete.

Yes, it is. If you will spend some time to locate the schematic for which these speakers were intended to be used with, I suspect the mystery will clear up.

[jjasilli]

Mr 200s comment about seeing the gear, and jjs 3db comment fired a synapsis to look into the voice of the theater cross over, which got me here;
https://www.soundandvision.com/content/living-legend-altec-lansings-%E2%80%98voice-theatre%E2%80%99
at which point I just surrendered

I lust after those Speakers.  If only I had a listening room large enough to house two of them plus my wife!

[Ritchie200]

We had 4 of those A7 VOTT for out PA back in the 70’s when the band had to bring their own PA. I plugged a little radio shack transistor radio into one and it sounded glorious!  Two of those four cabinets we built. We had to buy the plans. I’m not sure from where or who. I’m sure they can be found on line these days. They are big - and heavy!  About like a big 4x12 with real wood.

Jim

[shooter]

I lust after those Speakers

I have one, and a 2X15 JBL pro series, and a wife that STILL says NO!, so the cabs are in the barn, the VOTT cab is now a skeet throwing platform  .  I do use the VOTT 15 in an open-back PA cab for guitar, both JBL's need re-coning.
I  threw a party 10yrs ago and used both cabs with 2 100W SS amps and they rocked! Also had a twin reverb that the guitar player got to 8!!

[Ritchie200]

The horns got destroyed over the years of throwing them in a van and the back of pickups. We bought some white EV horns (? not sure what the heck they were) in road cabinets to set on top. If I remember, the curved part of the "horn" in the bass bin was like 1/4" Masonite that we glued to a couple of wood forms with the proper radius.  I could never understand why blocking off the ends of the speaker worked?      Those cabs were super efficient though.  It didn't take much to get them loud.  We just used Crown 300 amps straight up, no bi-amp - and they could get really loud. The only thing they seemed to have trouble with was when we miced the bass player.  He normally ran an SVT but also had a Model T for smaller gigs.  Those cabs would rattle pretty good on the lower freqs.

Jim

sorry old man reminiscing...

[shooter]

I'm hung up on the mounting for my carved horn and the JBL driver.
I think I read somewhere it's like 9Tesla!!!, I got weirded out in 3T, theorized I'd levitate at 9T 

[Ritchie200]

Oh that has to be an exterior mount!!!  Nice work!

Jim

[shooter]

exterior mount

the original horn was held on by 4 ~5/16 X ~ 2.5.
I can screw the "flange" (base of old horn), to the wood, but I have to "channel out" the wood for 2 bolts, I think
there's enough meat before I punch through the throat
still finalizing the amp, it's a long term project 

[1blueheron]

Mr 200s comment about seeing the gear, and jjs 3db comment fired a synapsis to look into the voice of the theater cross over, which got me here;
https://www.soundandvision.com/content/living-legend-altec-lansings-%E2%80%98voice-theatre%E2%80%99
at which point I just surrendered

I lust after those Speakers.  If only I had a listening room large enough to house two of them plus my wife!

Does your wife know you think she is that big?   

Your reminicsing take me back to some Altec Mantaray horns I had back in my youthful days.  Got hard up for cash and sold them on ebay.  Now I wish I had saved them but who knows where I would have stored them.

I am hoping to get a listening/music room back together some day.  A lot of projects need completed to get their.  I saved my old ESS AMT 1 speakers although they need new cabinets built.  Plan to rebuild and mod the old Eico ST  and my  Harmon Kardon T-65 turntable which lost its speed control and needs a belt.

The good part is I do have the space built out over the garage but it will need to be finished.  So many projects, so little time....