PSW 650 -11db roll-off at 35Hz

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Comments

  • kuntasensei
    kuntasensei Posts: 3,263
    edited December 2007
    Though I love my Polk speakers, I was never happy with either of my Polk subs. No matter how carefully I placed them in the room, they never gave me good output at the low end, and definitely never matched up to their spec'd response. In my opinion, subwoofers are Polk's achilles heel as far as enthusiasts go. They're great for your average consumer who doesn't know better and they will sound okay with music (since it primarily deals with mid to upper bass), but they won't have the bone-shaking bass that modern movie soundtracks can produce.

    That's why I ended up pairing a SVS 20-39+ with my Polks. Best money I ever spent, and I get flat corrected in-room response down to 18Hz (with significant output down to 12Hz, but I'm filtering that and letting my Buttkicker handle the really deep bass at the couch). Haunting DTS = 116dB with the clip light barely flickering, no driver bottoming. I recommend looking into online-only brands like SVS or Hsu, where the price vs. performance ratio is ridiculous compared to consumer grade subwoofers.
    Equipment list:
    Onkyo TX-NR3010 9.2 AVR
    Emotiva XPA-3 amp
    Polk RTi70 mains, CSi40 center, RTi38 surrounds, RTi28 rears and heights
    SVS 20-39CS+ subwoofer powered by Crown XLS1500
    Oppo BDP-93 Blu-ray player
    DarbeeVision DVP5000 video processor
    Epson 8500UB 1080p projector
    Elite Screens Sable 120" CineWhite screen
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  • PolkThug
    PolkThug Posts: 7,532
    edited December 2007
    haghighi wrote: »
    Polk reports a 25Hz floor, yet I am getting significant roll off at 40Hz!? What gives.

    Room null. Try taking a near field measurement.
    Never Forget
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  • haghighi
    haghighi Posts: 33
    edited December 2007
    PolkThug wrote: »
    Room null. Try taking a near field measurement.

    Not sure I understand?
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  • Ron Temple
    Ron Temple Posts: 3,212
    edited December 2007
    Run a series of test tones...sine waves...hold the SPL meter 1" from the driver, record the SPLs on a graph...you're getting the readings before the room interacts with the sound. Your frequency response should mirror Polk's specs. If they don't then something's wrong with the sub.

    Combo rig:

    Onkyo NR1007 pre-pro, Carver TFM 45(fronts), Carver TFM 35 (surrounds)
    SDA 1C, CS400i, SDA 2B
    PB13Ultra RO
    BW Silvers
    Oppo BDP-83SE
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  • haghighi
    haghighi Posts: 33
    edited December 2007
    Ron Temple wrote: »
    Run a series of test tones...sine waves...hold the SPL meter 1" from the driver, record the SPLs on a graph...you're getting the readings before the room interacts with the sound. Your frequency response should mirror Polk's specs. If they don't then something's wrong with the sub.

    I see so these are how the specs are done for subs? Even though I've had a full phase control calibration by a professional the room is the problem? Okay if this is the case then no sub would make a difference without room treatment correct?
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  • Systems
    Systems Posts: 14,873
    edited December 2007
    Ron Temple wrote: »
    Run a series of test tones...sine waves...hold the SPL meter 1" from the driver, ...
    And if it is a ported design you will also need to nearfield test it(port exit) as well.Otherwise you will only see the drivers contribution which will look rolled off without the ports response added.
    Testing
    Testing
    Testing
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  • Ron Temple
    Ron Temple Posts: 3,212
    edited December 2007
    haghighi wrote: »
    I see so these are how the specs are done for subs? Even though I've had a full phase control calibration by a professional the room is the problem? Okay if this is the case then no sub would make a difference without room treatment correct?
    The subs specs are usually done outdoors at 2 meters or in an anoechoic(sp?) chamber. By doing the extreme nearfield test, you should be able to find out if it's the sub or the room, nothing more. It won't fix the problem. I suspect something is wrong with the amp, since you've watched the driver and instead of getting more active below 40 it get's less. As someone else said, when you go lower the driver exhibits more excursion.

    Combo rig:

    Onkyo NR1007 pre-pro, Carver TFM 45(fronts), Carver TFM 35 (surrounds)
    SDA 1C, CS400i, SDA 2B
    PB13Ultra RO
    BW Silvers
    Oppo BDP-83SE
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  • haghighi
    haghighi Posts: 33
    edited December 2007
    Ron Temple wrote: »
    The subs specs are usually done outdoors at 2 meters or in an anoechoic(sp?) chamber. By doing the extreme nearfield test, you should be able to find out if it's the sub or the room, nothing more. It won't fix the problem. I suspect something is wrong with the amp, since you've watched the driver and instead of getting more active below 40 it get's less. As someone else said, when you go lower the driver exhibits more excursion.

    Well the amp is built in, I suppose if I use the line levels I would bypass the internal amp used with the LFE channel correct?
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