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Kappa 9 - correct amount of woofer damping material?

Discussion in 'Infinity Loudspeakers' started by MiamiBoy, Oct 25, 2018.

  1. MiamiBoy

    MiamiBoy Active Member

    Messages:
    429
    Location:
    NSB, FL
    Can someone provide some insight into the correct amount of damping material that should be in the woofer area of the Kappa 9's? How tightly/loosely should it be packed?

    When I bought my K9's the first thing I did was open up the speaker to inspect the wiring. The acoustical damping material behind the woofers looked like big cotton fluff that had yellowed, molded and was stuffed very loosely. By loosely I mean it looked as if someone very sparingly stuffed the speaker with just enough so the stuffing would not fall down. Not knowing better I replaced it all with new speaker damping material. I think I may have over packed it too tight now that I have learned how it is important to replace the same amount as the speaker designer intended. Paul of PS Audio, who worked a lot with Arnie, has a video on YouTube where he says Infinity took great care in experimenting with the proper amount of damping material until they got just the right amount and then used the exact same amount in each speaker of the same line.
     

     

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  2. pauljh

    pauljh Active Member

    Messages:
    196
    Location:
    San Francisco
    Kappa 9s are sealed cabinet speakers. Damping material in a sealed box speaker serves two purposes. First, it damps some of the backwave of the woofer and reduces echo of the backwave off the rear of the cabinet and re-radiating through the speaker cone. And, second, it can reduce the speed of sound in the cabinet thus making the cabinet appear larger to the driver. However, under most scenarios, the 2nd effect is very limited, and with loose filling material, there is almost no effect. So I wouldn’t worry about it. Where you place the speakers in your room will have a much bigger effect.

    Here is some additional reading...
    https://data-bass.com/data?page=content&id=79
     
    Last edited: Oct 25, 2018
  3. 7.62

    7.62 Gearhead Subscriber

    Messages:
    1,604
    Location:
    Las Vegas
    Kappa 8 X2, Crescendo 3007 & 3009, Rs2b, rs2.5 & rs4.5, all of them are about the same to me. You should have some light to medium resistance when reinstalling the woofer. Some of these had a cheesecloth backing also to keep the stuffing from entering the woofer basket.

    HTH.
     
  4. seifreit

    seifreit New Member

    Messages:
    11
    Location:
    West Central Fla
    I agree with last sentence of pauljh's post. I just got my Kappa 9s set up a couple weeks ago and was initially disappointed in the bass performance. I've been tweeking the placement and was amazed at how much location affected the bass. Totally different sounding from what they were when I first set them up.
     
  5. MiamiBoy

    MiamiBoy Active Member

    Messages:
    429
    Location:
    NSB, FL
  6. MiamiBoy

    MiamiBoy Active Member

    Messages:
    429
    Location:
    NSB, FL
    Thanks for the replies. I may have over stuffed them a bit but I am getting very good bass so will leave well enough alone.

    What I did with these speakers with very good results is rewired the woofers directly to the speaker posts bypassing the LF crossover completely. The amps I am using, Crown 2500's have a built in cover function which I crossover at 95 Hz. Each amp is bridged. Rewiring direct raised the impedance from 1ohm up to 6ohms. No longer amp killers. The beasts were tamed.

    On top I have a Cary V12R with EL34 tubes. Very happy with the results.
     
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  7. 7.62

    7.62 Gearhead Subscriber

    Messages:
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    Location:
    Las Vegas
    Nice man, I’m using a single Crown 2502 and it has no problem pushing 4 Watkins woofers. I hope to find a nice tube amp like yours to handle duty on the top end of my 4.5 speakers. I bet that sound good as heck, nicely done.
     
  8. MiamiBoy

    MiamiBoy Active Member

    Messages:
    429
    Location:
    NSB, FL
    Today I rewired my K9's back to passive using the internal covers instead of wired active using the external cover in my Crowns. They sound much better using the internal passive xovers in the K9's with the two Crown 2500's in bridged mode. Lesson learned. Don't do that.

    While there is strong bass wired active and the impedance is much higher making it easier on an amp to drive, it should only be used as temporary option if one doesn't have an amp adequate to drive the lower end. I was using the internal active LF crossover function of the Crowns which are not high end. Maybe if someone had a better active crossover it would sound better, I don't know. But wiring active does require some external crossover somewhere.

    It took me awhile to realize the problem as I was focusing more on the amount of bass rather than how well it was integrating with the rest of the music. Sounded like the phasing or timing of the bass was slightly off. I have another system in the house which I would consider my "reference" system with higher end mono amps and more accurate speakers. Listening to that made me realize the K9's wired active didn't sound right. So I wired them back and it sounds much better now.
     
    Last edited: Oct 28, 2018

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