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

Discussion in 'Speakers' started by DangerBoy, Oct 20, 2017.

  1. nh36000

    nh36000 Holdin' down the fort! Subscriber

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    DB;

    Dang! I bought one of those without the radio as my first stereo in '68 or '69. 'Still have it. I thought the world of the omnis.

    I'm curious, I'm going to keep an eye on this thread.

    Lu.
     

     

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  2. DangerBoy

    DangerBoy Active Member

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    Ever take one of those speakers apart to have a look inside? I'm still trying to figure out how to get into them without damaging or destroying the bottom plates.
     
  3. 2chman

    2chman Well-Known Member

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  4. tarior

    tarior Dirty pool, old man? Subscriber

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    Yer gonna need all the volume you can get in those little cabinets. Just hide your powered sub under something or in a corner.
    Also, that thing will not have anywhere near enough power to drive a woofer.
    Pretty much all powered subs that have speaker level inputs have a high pass filter for the satellites. You'll want to use it. You'll get way cleaner sound from what is probably at best a 5wpc amplifier.
     
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  5. DangerBoy

    DangerBoy Active Member

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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!


    When I got the bottom off this is what I found:


    I removed the insulation puck out of the bottom and this is what there was:


    I took out that inch thick insulation blanket and this what there was:


    The driver is 6.5" in diameter. The inside diameter of the enclosure is pretty much 8-3/8". The inside diameter of the plywood ring at the base of the speaker is 7-1/8" or maybe 7-3/16". It could certainly be enlarged some to allow a bigger driver to be passed through.

    The vertical height from the base of the plywood that the driver is mounted to to the base (top in this picture) of the plywood ring is about 5-3/4". We don't have a lot of volume to work with.

    So this is what we have to work with. Okay, people let's work the problem. ;-)

    I'm not an expert on speaker design so I have to ask what we could possibly gain or lose in bass response by adding a vent to the enclosure? And this may also be a stupid question but it's worth it to ask: What about a coax or full range out the top and a passive radiator out the bottom? What effect would that have? Again, forgive me these are stupid questions.
     
  6. tarior

    tarior Dirty pool, old man? Subscriber

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    That's perfect for some nice 6-1/2" two way car speakers. MB Quart, Focal, Kenwood, Pioneer, the selection is huge.
    Port, don't port ( a passive radiator is essentially the same thing as a port), doesn't matter. You will need a powered sub. Period.
    You asked for serious advice, I'm giving it.
     
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  7. 2chman

    2chman Well-Known Member

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    Waiting for Alan Funt to Jump out!
     
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  8. tubed

    tubed Lunatic Member

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    Simply rework the cabinet.
    Preferably a transmission line.
    00c23e1fc87af6d22da9ae648cdc7bad.gif
     
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  9. valvenator

    valvenator curious bystander, serious procrastinator Subscriber

    I like how you said "Simply" then added "transmission line"
     
    Last edited: Oct 20, 2017
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  10. swechsler

    swechsler Frog Whisperer

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    I answered this question in my first response...
     
  11. Porkloin

    Porkloin Oscar Heil Groupie

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    You're just about there. All you have to do is turn the driver around. Maybe chop off some of the pointy white thing if that doesn't destroy the retro charm too much.....


    OhmF.jpg
     
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  12. tubed

    tubed Lunatic Member

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    .....and then there's bi wiring.
    The sky's the limit.
     
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  13. swechsler

    swechsler Frog Whisperer

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    A transmission line in a cylindrical cabinet? How would that work?
     
  14. valvenator

    valvenator curious bystander, serious procrastinator Subscriber

    If you're really serious about this, 'tarrior' offers solid advice. Porting the cabinet will require a bigger cabinet.
    Find some car speakers or full range drivers from Parts Express that will work in a cab that size and add a sub,
    preferably one that goes a bit high, maybe 150 hz, placed between the two speakers and you might have a decent system.
     
  15. sqlsavior

    sqlsavior AK Subscriber Subscriber

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    Maintain a sealed alignment. It was chosen for good reasons, imo.

    One thing you haven't told us is how they sound as they are now? Have you listened to them? I would think that placement is paramount to achieving a satisfactory result. Have you experimented with placement any?

    Is the disperser stalactite (my terminology :rolleyes:) rigid and non-absorbing?

    How they sound as-is might affect your goals and choices...
     
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  16. Tom Brennan

    Tom Brennan AK Member Subscriber

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    Like this.

    IMG_4374.JPG IMG_4375.JPG
     
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  17. Tom Brennan

    Tom Brennan AK Member Subscriber

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    I wouldn't assume the drivers are poor quality; might be that all the speakers need is a sub and better source and amplification.
     
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  18. PioneerGuy75

    PioneerGuy75 Certified Lurker

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    I had a pair of those long ago...I took em apart and put a pair of Kraco 6.5" car speakers in them. They sounded OK....That has been a long time ago!
     
  19. valvenator

    valvenator curious bystander, serious procrastinator Subscriber

    Excellent point. My father in law had minimus 7's plugged into his all-in-one stereo and of course they sounded like crap.
    Recently picked up a pair cause they were cheap and tried them with my Technics receiver, difference was night and day.
    Maybe the OP needs to try some better speakers with the system, or a better system with the speakers to see if it makes much of a difference, before investing any more time and money into the project.
     
    Last edited: Oct 20, 2017
  20. Katalyst

    Katalyst AK Subscriber Subscriber

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