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  1. #1

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    Default Using 2 different subs

    I built 2 completely different subs. I am trying to get them to work together but not having much luck.

    1st sub (S1) is a SVS DiY. 12.1 SVS driver in a 4 cuft incloser with a 4" port aprox 18"long.

    2nd sub (S2) is a Dayton 12" DVC in a 3.0cuft sealed incloser.

    Both subs have the same plate amp (Rythmik audio 350A)

    As you can see in the diagram, I have each sub in oposite corners from each other. I have calibrated the phase.

    I set the correct phase with S1 with the mains, then phased S2 to S1.

    The mic was placed in the center of both recliners (Rec).

    I am getting the same dB reading with one sub playing (S1) as with both subs playing.

    My assumption was by adding a second sub (S2), in the oppsosite corner, my dB's would increase by 3db's.

    Is my phasing wrong or is it because one sub is ported and the other is sealed?

    The reason that S2 is in opposite corner and not in the same corner, is because of a null I'm trying to correct in Rec listening position.

    With both subs in the same corner I do get and increase in dB's , but only at one position. I'm trying to utilize the 2 subs to get a fuller preasurized room.

    I have read many times, that if 2 subs cannot be put in the same position (stacked or otherwise), then the subs should be put at opposite corners, adjacent from each other.

    Any thoughts that I may be missing?
    The room is 16W x 22L x 9H

    Jake
    Attached Images  
    Monitor 7b's front
    Monitor 4's surround
    Frankinpolk Center (2 mw6503's with peerless tweeter)
    M10's back surround
    Hafler-200 driving patio Daytons
    Tempest-X 15" DIY sub w/ Rythmik 350A plate amp
    Dayton 12" DVC w/ Rythmik 350a plate amp
    Harman/Kardon AVR-635
    Oppo 981hd
    Denon upconvert DVD player
    Jennings Research (vintage and rare)
    Mit RPTV WS-55513
    Tosh HD-XA1
    B&K AV5000


    Dont BAN me Bro!!!!

  2. #2
    Polk Customer Service
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    Default

    Not recommended to use 2 different subs in the same airspace. The different tuning frequencies and designs of both subs will reinforce each other at certain points and cancel each other out at others. If you're going to use more then one sub, make sure they're either identical models or handling different parts of the frequency spectrum.

    In your case, use one or the other. Not both.
    -Eric
    -Polk Audio

  3. #3

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    Default

    Quote Originally Posted by Eric Wong View Post
    Not recommended to use 2 different subs in the same airspace. The different tuning frequencies and designs of both subs will reinforce each other at certain points and cancel each other out at others. If you're going to use more then one sub, make sure they're either identical models or handling different parts of the frequency spectrum.

    In your case, use one or the other. Not both.
    Thanks Eric,

    I did notice the 2 are doing a good job correcting the nulls in the room. But not a good job increasing the dB level.

    Phase adjustment would not fix this issue?
    Monitor 7b's front
    Monitor 4's surround
    Frankinpolk Center (2 mw6503's with peerless tweeter)
    M10's back surround
    Hafler-200 driving patio Daytons
    Tempest-X 15" DIY sub w/ Rythmik 350A plate amp
    Dayton 12" DVC w/ Rythmik 350a plate amp
    Harman/Kardon AVR-635
    Oppo 981hd
    Denon upconvert DVD player
    Jennings Research (vintage and rare)
    Mit RPTV WS-55513
    Tosh HD-XA1
    B&K AV5000


    Dont BAN me Bro!!!!

  4. #4

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    Default

    I use a 15" Velo and a 10/12" Velo. They work fine together but they are different sizes and the 15" goes lower and 10/12" is tighter so they go together well.
    engtaz

    I love how music can brighten up a bad day.

  5. #5

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    Default

    The sealed Dayton , (being sealed) I was hoping to take advantage of its "punch" between 35 and 70hz. The SVS, (being ported) I was hoping to take advantage of its depth 18-35hz. But its not working out as I planned. I didnt know if it was a phase or placement issue.

    I dont want to have turn a sub off...booohoooo...:( :( :(
    Monitor 7b's front
    Monitor 4's surround
    Frankinpolk Center (2 mw6503's with peerless tweeter)
    M10's back surround
    Hafler-200 driving patio Daytons
    Tempest-X 15" DIY sub w/ Rythmik 350A plate amp
    Dayton 12" DVC w/ Rythmik 350a plate amp
    Harman/Kardon AVR-635
    Oppo 981hd
    Denon upconvert DVD player
    Jennings Research (vintage and rare)
    Mit RPTV WS-55513
    Tosh HD-XA1
    B&K AV5000


    Dont BAN me Bro!!!!

  6. #6

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    Mine are locate up front on either side of the audio equipment. Your problem could also be placement. Move them around to find what works.
    engtaz

    I love how music can brighten up a bad day.

  7. #7
    Polk Customer Service
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    Well one of the issues is the different tuning frequencies... yes 2 subs placed asymmetrically in a "small" (less then 100 foot) room can smooth out the frequency response.

    If you're using a sealed box, it has very little phase shift through the frequency range. If you're using a ported box- as you get closer to the tuning frequency, the more phase shift you will get. Unfortunately you cannot correct this simply using a phase switch or shifter.

    Mixing different subs = no no. Mixing different designs of enclosures = even bigger no no.
    -Eric
    -Polk Audio

  8. #8

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    Default

    So I guess I have it as good as I can get it. In phase and correcting nulls. Becides that, not much else I can do.

    I could port the sealed sub. But it does sound very good. I guess I'll leave well enough alone, if I cant correct the phase.

    I ran a sine waves @ 30-40hz and phased it in there and only -2dB's @ ~20hz. Sacrificed the upper Fr's, but my 7b's do a good job handling 50hz and above range..
    Last edited by jakelm; 05-03-2007 at 01:40 PM.
    Monitor 7b's front
    Monitor 4's surround
    Frankinpolk Center (2 mw6503's with peerless tweeter)
    M10's back surround
    Hafler-200 driving patio Daytons
    Tempest-X 15" DIY sub w/ Rythmik 350A plate amp
    Dayton 12" DVC w/ Rythmik 350a plate amp
    Harman/Kardon AVR-635
    Oppo 981hd
    Denon upconvert DVD player
    Jennings Research (vintage and rare)
    Mit RPTV WS-55513
    Tosh HD-XA1
    B&K AV5000


    Dont BAN me Bro!!!!

  9. #9

    Member Sales Rating: (4)

    Join Date
    Jan 2005
    Location
    LSU, Louisiana "In a galaxy far far away"
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    Quote Originally Posted by Eric Wong View Post
    If you're using a sealed box, it has very little phase shift through the frequency range. If you're using a ported box- as you get closer to the tuning frequency, the more phase shift you will get.

    As the Fr gets closer to the tuned Fr, in my ported incloser , the phase is shifted in which direction 0 or 180?
    Monitor 7b's front
    Monitor 4's surround
    Frankinpolk Center (2 mw6503's with peerless tweeter)
    M10's back surround
    Hafler-200 driving patio Daytons
    Tempest-X 15" DIY sub w/ Rythmik 350A plate amp
    Dayton 12" DVC w/ Rythmik 350a plate amp
    Harman/Kardon AVR-635
    Oppo 981hd
    Denon upconvert DVD player
    Jennings Research (vintage and rare)
    Mit RPTV WS-55513
    Tosh HD-XA1
    B&K AV5000


    Dont BAN me Bro!!!!

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