How to get the best sound possible out of these vintage Circle of Sound babies

I remember those systems - mid-century modern if there ever was an example.

IIRC, the cabinets are plastic, correct, as is the grill work on the top? If so, then the challenge for a more high-excursion driver will be the back pressure on the cabinet. I'd suggest you line the round cabinet with some of that sound-deadening material used by auto sound installers to keep doors and trunks from vibrating. Then put the insulation back into the cabinets after the replacement drivers are installed.

Both will lower the efficiency of the speaker but will linearize the bass response. Don't expect room filling bass but do expect to be presented with a nice sound stage assuming the speakers are placed well enough. Also, I'd suggest other electronics than the old console. A nice Pioneer, Sony or Sansui receiver of the the 70s vintage would be far better.

Cheers,

David
 
I'm looking forward to hearing your thoughts on your completed project. The idea of damping the inside is good. Spray on bed liner would also work>> I would go with which ever is cheaper. I love a good DIY thread !!!.
 
Best of luck on this project. :thumbsup:

A buddy of mine got either this system or one nearly identical for his birthday. I'm guessing around 1968 but could be off by a year or two. I remember it sounding decent for what it was, and in fact filled his room with sound quite nicely.

I tend to believe most things can be improved with a little effort and there's no reason not to do it with this system. I'll be curious as to what improvements can be gained with a bit of brainstorming combined with building / modifying.
 
Does anybody know what the impedance of the original full range (Zenith 49-1116) drivers in these speakers is supposed to be? I measure 6 ohm with my multi-meter.
 
Looks like big fun to me......if you can get a 3rd speaker you could make an isobaric subwoofer out of it by placing to Tang Band drivers face to face after removing the omni cone. An Anarchy woofer/s might fit and might also be used in the omni canisters but the tweeter mounting remains a problem. You could also use Alpair 10.3 full range drivers which will work in 0.25 ft3. The icing on the cake would be finding/using a pair of Infinity Walsh tweeters mounted on top.
 
Caution: zombie thread!

I am wondering how the OP made out.

I just acquired a pair of these for free from the side of the road and want them to sound better.

My first step is to reseal the cabinets, as the bottoms have holes in them. After that, I am thinking car stereo coaxial.

BTW, the bodies are cardboard (think Sonotube) with steel rings top and bottom for strength. Legs are held on with screws through the cardboard. Bottom is pressboard. Top is a plastic screen material. "Top hat" is pressboard. Diffuser cone is hard plastic. All covered in woodgrain vinyl.

Pretty cool to look at, let's see how they can sound...
 
It would have been kewl to find out what happened. As I understand it, several mfgs came up with these round omni-directional speakers and it would be interesting to hear of assessments.
 
I, too, wonder what the OP ended up with in the end. I've been keeping an eye out for a pair of these for cheap for this same reason for a few years now. Some additional sealing, damping, and better drivers would certainly improve things. I'm on the train of thought that some acceptable sound can bet gotten out of them with a little work, and they could be used for garage or background music. My plan, originally, was to get a pair and try mounting them on my garage ceiling, after the improvements, to see if I could get some uniform-ish sound throughout the garage.

They are an interesting novelty with no sonic value as-is. Tinkering with them is fun, potentially rewarding, and in the end they can still be resold to be used as the bad sounding decorations they came as, only with improved sound.
 
I, too, wonder what the OP ended up with in the end. I've been keeping an eye out for a pair of these for cheap for this same reason for a few years now.

Fun project. Make your own. Grab a concrete form tube and go to town. Let us know how you do.

GeeDeeEmm

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OK, step one: get them back to factory condition.

That was easy, I just cleaned them out and made new bottoms for them to reseal the cabinets.

Result: medíocre. Not great, but better than I expected. Very highs and lows are not there, but the mid is OK. My Mac 4100 has a built in EQ and variable loudness. If I crank the 10K EQ and crank the Loudness to boost the bass, they are not bad at all.They pull quite a bit of power, 3 W at mid volume which surprised me; not efficient at all. (This is what my AR-3s draw at a much louder volume.)

Next step: better drivers. Not looking to sink $$ into these, so I'll look for used car audio coaxials.

Stay tuned.
 
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I once had the very system you show in your photo. The big deal was the 2 gram turntable tracking weight. I recall the Circle of Sound Speakers sounded pretty good. My advice is to get one of the Lepai LP-2020TI audio amps from Parts Express; $28.88. I have 3 of these amp and I can say with confidence the 2020 is a vast improvement over the amp in the Zenith. The 2020 is 20 Watts x 2 into 4 Ohms which would less the 20 Watts into 8 Ohm which would be prefect for these speakers. You can use a 3.5mm cable to input a signal from a smart phone, or better yet an Echo Dot into this amp.

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These are small right ?
They're also lacking in hifi characteristics.

Why not use them for the surround channels.

the surround channels cut the bass off at around 120Hz from memory and the treble at a round 7k. This is because that band of frequencies between those limits is the one that conveys the directional/spatial information to the listener.

This way you arent trying to make something of a sows ear but rather using their very limited frequency response to your advantage.

It's no coincidence that surround sound speakers are small and cheap looking. That's all they have to do... spread a very limited portion of the sound.
 
I used a set of Kenwood coax car speakers as replacement drivers and a passive radiator in the bottom. With a little equalization to boost the off axis treble they make fun desktop speakers and are nice and airy with the omni design. An 8" subwoofer under the desk makes them quite acceptable.
 
I'm a huge fan of Zenith drivers pulled from 50's and early 60's tube consoles. If you see any that look similar to these grab'em because they are beyond amazing.

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Okay, I got one apart. Here's how: I wrapped some cord around the speaker wire racks in a figure 8 to make a handle that I could get a halfways decent purchase on and pulled like hell. It worked but I had to give it a damn good pull to get it out!

Created an account here just to say thank you for posting this! I got a pair of these in an auction and have been trying to figure out why the bottom won't come off, even after removing the screws. I appreciate your level of detail in your documentation!
 
Wow - 4 pages, but has anyone actually listened to the speakers, than immediately starting to change them?
I've had several pairs, and used with decent source and amplification sound surprisingly decent. Bass is improved by the fact that they are on the floor. The whizzer gives reasonable extension in the high end, and the diffuser does a good job of creating very wide dispersion. They make excellent outdoor speakers.
No they will never be great, but I have my doubts about how much better they can be made - the cabinet volume is too small to produce much bass from any driver, and almost any driver that will be efficient enough for the console amp is going to be more or less similar to the existing one. And remember that the more drivers you use, the more power you need,and you loose a coherene and dynamics that full range drivers, for all their faults, often have in their favor.
You can use a different amp, but then you lose the retro look, which was the whole point. (Yes you can tuck another amp in there, but if you are going the fake route, you might as well use hidden full range speakers and just pretend that you are listening to the circle of sounds.
I'd check the sealant on the surrounds - I remember them being doped cloth, and often they get leaky, and that doesn't help. Other than than, I'd find a more promising enclosure for DIYing.
 
Wow - 4 pages, but has anyone actually listened to the speakers, than immediately starting to change them?
I've had several pairs, and used with decent source and amplification sound surprisingly decent. Bass is improved by the fact that they are on the floor. The whizzer gives reasonable extension in the high end, and the diffuser does a good job of creating very wide dispersion. They make excellent outdoor speakers.
No they will never be great, but I have my doubts about how much better they can be made - the cabinet volume is too small to produce much bass from any driver, and almost any driver that will be efficient enough for the console amp is going to be more or less similar to the existing one. And remember that the more drivers you use, the more power you need,and you loose a coherene and dynamics that full range drivers, for all their faults, often have in their favor.
You can use a different amp, but then you lose the retro look, which was the whole point. (Yes you can tuck another amp in there, but if you are going the fake route, you might as well use hidden full range speakers and just pretend that you are listening to the circle of sounds.
I'd check the sealant on the surrounds - I remember them being doped cloth, and often they get leaky, and that doesn't help. Other than than, I'd find a more promising enclosure for DIYing.


I’m going through this thread because one of mine is dead. If I’m going to replace the speaker, I might as well try and find a better driver. The one that I have sounds kind of dead and flat, very pesky in the mid with no bass what so ever. My minimus 7s sound about 900x better. I’d just like to refurb these, make both of them work and sound good....

I’d love to find an early 90s MB Quart 6.5” coax which would sound incredible in this size cabinet, but I am not going to find a set at a reasonable price.

‘I’d also love to see some output tests once people swap drivers or mod the enclosure, but I know that’s asking too much.
 
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