Old School Polk Audio C4 Subwoofer - Four 6x9's in Isobaric Teardrop Enclosure

BigDWizBigDWiz Posts: 12
edited September 2012 in Car Subwoofer Talk
I wasn't sure if this should go in the Vintage Speaker section or the Car Audio section, but since it's car audio, I decided to put it here. I just picked up this MINT 1992'ish Polk C4 subwoofer from a local CL ad. I took off the bottom panel to show off the "guts" and plan on doing a video demo soon.

(info below was found in an older post in the vintage speakers section. I also found an Ad in a 1992 Car Audio & Electronics and a test in a March/April 1992 Car Stereo Review. I'll post these as soon as I get them scanned in)

Here's a Polk Audio C4, circa 1992. Original MSRP was around $500.

I took off the bottom panel so you could see the goodies. I'll do a video demo soon, so stay tuned...

Driver complement - Four 6x9 drivers monted in a isobaric push pull configuration
Enclosure type - 4th order bandpass
Frequency response - 25 to 150 Hertz
Sensitivity - 94 db @ 1 Watt @ 1 Meter
Recommended amplification - 25 to 200 Watts per channel
Impedance - 4 Ohm stereo, 2 or 8 Ohm mono
Dimensions - 8" H x 26.25" W x 17.125 D
Weight - 26 pounds




Post edited by BigDWiz on


  • BigDWizBigDWiz Posts: 12
    edited February 2012
    Mods feel free to move this to the Car Subwoofer section...I should've looked at all of the forum titles before posting :redface:
  • DSkipDSkip Posts: 12,902
    edited February 2012
    Curious on your impressions. We have one of these in the area that pops up on CL every now and then. I thought about picking it up, but have zero use for it. The price was more than reasonable.
  • BigDWizBigDWiz Posts: 12
    edited February 2012
    I picked it up late yesterday and haven't had a chance to fully test it out in my car. I tested it for functionality only, but I'm planning on doing an entire video demo of the unit and will also give my impression of the subwoofer. I currently have a JL Audio 12w6v2 in my car, so I don't expect that level of output, but clean, hard hitting bass is really what I prefer anyway. I'll be sure to post the video here and any follow up impressions.
  • BigDWizBigDWiz Posts: 12
    edited February 2012
    Each 6x9 in the enclosure has a date written on it (Sharpie?) and I've looked as close as I can and it still looks like 12/18/98 to me. It would make more sense to be either 91/92/93, but it looks like an 8 to me. Maybe the 6x9's were replaced or my eyes are deceiving me?
  • BigDWizBigDWiz Posts: 12
    edited February 2012
    Here's an Ad from a May 1992 CA&E magazine:

  • BigDWizBigDWiz Posts: 12
    edited February 2012
    And the CSR test from March/April 1992 as mentioned in the Ad...

    Still confused why my speaker input terminals are on the opposite side of the box?? Can anyone who has one of these confirm which side the terminals are on their box? :question:


  • MacLeodMacLeod Posts: 14,362
    edited February 2012
    Now thats just damn cool, I dont care who ya are.
  • hoosier21hoosier21 Posts: 4,383
    edited February 2012
    MacLeod wrote: »
    Now thats just damn cool, I dont care who ya are.

    That is a neat find
  • BigDWizBigDWiz Posts: 12
    edited February 2012
    Thanks guys...I put it in my car yesterday and have put it through a few listening tests powered by around 300w. It sounds VERY nice! Not the window flexing bass output of my JL Audio 12w6v2, but clean and loud enough to feel the kick. It would be a superb upgrade to a factory system to give some extra punch. The teardrop shape makes it easy to fit in many applications. I put together a video overview and demo of the C4 and will post it here when it's been uploaded.
  • VitalVital Posts: 747
    edited February 2012
    That IS nice!
    I wonder why enclosures/subs like this aren't being sold nowadays. Seems like it puts out a lot bass especially for the size they are which as mentioned fits just about anywhere due to "teardrop" shape..
  • BigDWizBigDWiz Posts: 12
    edited February 2012
    Finished up the video today and finally got it uploaded. See below:

    Watch on YouTube in 1080P HD or embedded below:
  • IJGNIJGN Posts: 1
    edited March 2012
    Wow, I just had to register for this post. Brings back awesome memories! I had 2 of these maybe 8 years ago. These dont really sound all that great in a trunk, but I put one on the rear shelf area of a camaro SS and wow, the hatchback really made it sound like a decent quality 12 was back there, and the SQ was TIGHT.

    I will remark that there appeared to be 2 versions of this box. One I suspect was much earlier, with silver frame, paper cone drivers, looked much cheaper inside. The construction of the curvature was different too, and not as good, as it totally "collapsed" rendering the box junk, the area where the slats are doesnt appear to be thick enough. Was powered with 350 watts RMS IIRC, not a problem but I believe the earlier version developed a coil knock/scratch.

    I also had a version much like yours with the rubber surrounded black drivers, and I could have sworn the curvature part was totally smooth inside, as if they perfected the construction even better.

    Really wish I could find another mint one, just to have. Sold one to a reluctant corvette owner who was more than thrilled with the sound after installing it.
  • JstasJstas Posts: 13,451
    edited May 2012
    I have one of these.

    I've posted about it before.

    I've used it as a home sub as well for a home theater.

    Stellar sub!
  • -FROG--FROG- Posts: 30
    edited September 2012
    Cool sub indeed.
  • if your ready to sell the c4 im ready to buy. :-)
  • I found one and traded for it but it wont fit in the back of my mustang...It also came with a amp and crossover.

    What would something be worth on the open market?
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