Polk Should Change Box Recommendations

only126db
only126db Posts: 157
edited June 2008 in Car Audio & Electronics
I have two Polk DX 12's and for the life of me was hating them....

They sounded like crap!!!

I tried .85 cu ft sealed, 1 cu ft sealed and they just sounded terrible.

Finally I tried 2 cu ft ported tuned to between 28 and 30hz and now they sound great...

I was originally looking to buy 2 more but with them not performing in the first boxes I changed my mind, now I may be trying to find another pair....

I have to run them in series(8ohm) on my amp due to the ohm load so they are only seeing 75-100rms each and surprisingly they get pretty loud, with about 50 rms more per sub the sound would clear up a bit more and they'd be great....

So Polk should change the recommendations and atleast say they can be run ported...

Too bad it wont happen since they are discontinued...
Post edited by only126db on
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Comments

  • MacLeod
    MacLeod Posts: 14,358
    edited May 2008
    Dont know about the DX series but I know for a fact and can attest to the specs for both Momo and SR subs being spot on.
    polkaudio sound quality competitor since 2005
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  • only126db
    only126db Posts: 157
    edited May 2008
    MacLeod wrote: »
    Dont know about the DX series but I know for a fact and can attest to the specs for both Momo and SR subs being spot on.

    Check out my vid I just posted...ported boxes...
    http://www.polkaudio.com/forums/showthread.php?t=68050
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  • Jstas
    Jstas Posts: 14,820
    edited May 2008
    Um, they aren't supposed to be run ported because of the way they are designed. Suspension compliance, cone travel and such are all designed around a sealed enclosure. Your DX12's have too much cone mass to be effective in a ported box and survive. You're gonna destroy your subs in a few months. It's a shame too because while they aren't quite as nice as the dB12's they replaced, they are nice subs.


    What makes them "sound like crap"? Because honestly, I've never heard that assessment of the old dB or DX subs, ever.
    Expert Moron Extraordinaire

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  • ben62670
    ben62670 Posts: 15,969
    edited May 2008
    beijmanli wrote: »
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    reported
    Please. Please contact me a ben62670 @ yahoo.com. Make sure to include who you are, and you are from Polk so I don't delete your email. Also I am now physically unable to work on any projects. If you need help let these guys know. There are many people who will help if you let them know where you are.
    Thanks
    Ben
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  • thumpin07
    thumpin07 Posts: 217
    edited May 2008
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  • addikt
    addikt Posts: 36
    edited May 2008
    i too vouch for polks recommended box dimentions i run my sr104s in a .67cuft box recomended is .66 and they sound fantastic
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  • Eric W
    Eric W Posts: 556
    edited May 2008
    Our box recommendations aren't just made from a hypothetical computer program. We actually test them out in a lab environment and in actual vehicles.

    That being said, DX uses a high mass cone- it's not suitable for use in a ported enclosure. But thanks for the suggestion, we do value input from the end user.
    -Eric
    -Polk Audio
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  • tk421
    tk421 Posts: 156
    edited June 2008
    sealed enclosures need a *LOT*of power. ported are more efficient but as the polk rep said.. u may destroy the speakers if u do not do some things properly (and that's a whole other topic!)
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  • only126db
    only126db Posts: 157
    edited June 2008
    tk421 wrote: »
    sealed enclosures need a *LOT*of power. ported are more efficient but as the polk rep said.. u may destroy the speakers if u do not do some things properly (and that's a whole other topic!)

    I tried each in .85----.88
    1.0
    1.2
    1.5----cu ft sepertate sealed boxes.

    I am running an MTX Blue Thunder Pro150x2 which is rated:
    RMS Power measured at 12.5 Volts DC:
    75 watts x 2 into a 4 ohm load with less than 0.05% THD+N
    150 watts x 2 into a 2 ohm load with less than 0.1% THD+N
    300 watts bridged into a 4 ohm load with less than 0.1% THD+N

    Dynamic Power (IHF-202 standard) measured at 14.4 Volts DC:
    120 watts x 2 into a 4 ohm load
    212 watts x 2 into a 2 ohm load
    425 watts bridged into a 4 ohm load

    Signal to Noise Ratio
    > or = 110dB A-Weighted

    Damping Factor:
    >200

    Maximum Input
    8 Vrms

    Frequency Response
    20Hz-20kHz ±0.25dB

    (my electrical runs @ 13.6v and didn't drop below 13.2v on this amp)

    I now have 2 of them in seperate ported 2cu ft boxes(after displacement) tuned to approximately 30hz running 75x2 the sound is much cleaner and more accurate, the bass seems to follow the music and be on a more even keel not as peaky as before.

    From 80-50hz it was too punchy.

    I believe alot has to do with my vehicles resonant frequency.

    Heres what it sounds like right now...
    th_DrumSolomov1.jpg
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