Should Dual Subwoofers Be Identical Models?

Discussion in 'General Audio Discussion' started by musichal, Jan 1, 2018.

  1. E-Stat

    E-Stat Addicted Member

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    As it turns out, there are room modes in the family room at 40 and 80 hz and I don't have the bass trap solution there as I do in the music system. 80 hz simply worked out empirically delivering the most linear results still leaving a trough in the 40 hz region. The Acoustats do have good response lower, but I followed the numbers.

    [​IMG]
     
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  2. JoeESP9

    JoeESP9 ESL's & tubes since 83

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    FWIW: I use a DSP to equalize and phase adjust my subs. I use REW and a calibrated mic to adjust and set it. No trying to do it by ear for me.
     
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  3. awillia6

    awillia6 Well-Known Member

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    Huh? You're bringing in localizable higher frequencies to show lower frequencies are localizable? How exactly does that instrumental "amenability" of yours affect the (non)ability to localize low frequency sound?
     
  4. biscuithead

    biscuithead Me likes the eargasm retroplasm... Subscriber

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    You should put them on top of those tiny feather-light speakers you got in the corner... maybe the subs will keep them from floating away...

    I'm so jealous. :beerchug:
     
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  5. tubed

    tubed Lunatic Member

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  6. musichal

    musichal poet emeritus Subscriber

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    Read carefully. I suggested that you should turn off the main speakers and try some test tones for yourself and find where you can hear your left from your right sub (use your balance control). In case you use music for this instead, is the reason I mention turning the main speakers off so they don't fool you into hearing a difference not attributable to the sub itself (few people go to the trouble to use test signals, ime). Got it?

    Also note that instrument timbre can include frequencies still within the sub's output range. That's why the "amenable" comment.

    Also, do you think LF becomes suddenly locatable at 80hz? Or do you think that the difficulty in locating the source of a 20hz sound the same for 80hz? LF becomes increasingly locatable as frequency rises... Do I really need to belabor these points?
     
    Last edited: Jan 1, 2018

     

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  7. awillia6

    awillia6 Well-Known Member

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    So the good doctor prescribes one big boy and multiple EQ'd units to handle higher freqs, especially around the handoff to the mains. Makes sense and the guy has a PhD in this stuff unlike, um, everyone else here, myself included.
     
    Last edited: Jan 1, 2018
  8. pch300

    pch300 Member

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    Awillia6 and musichal are both correct.

    Even a bass instrument at 41 Hz can have overtones/harmonics that could betray the location of the source if the string is not excited only in its fundamental mode. One would have to test with pure sine waves to see what frequencies can be located by ear with a subwoofer.

    Awillia6, I was an alien a long time ago, but became a citizen when I was a kid (LOL). No, I am not familiar with the research on sound localization vs. frequency.

    My main front speakers will go down to below 25 Hz - subwoofers about the same. Only use subwoofers in Home Theater mode to get the LFE (0.1) channel on 5.1 theater sound, so set at default 80 Hz crossover at the BluRay disk player. When I only had one subwoofer, easy to point to the LFE sounds coming from that location of the subwoofer. With two, it's more diffused around the room - great when things explode on-screen.

    In two-channel stereo listening, subwoofers are not used, with full range sound sent to the main front speakers.
     
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  9. awillia6

    awillia6 Well-Known Member

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    IOW, you have the Geddes setup: one big boy and dual identical subs occupying the nether regions of your mains both physically and sonically. All you lack is actively EQing the "pair" of subs to handoff smoothly up to your mains and down to the big boy. With luck and a few CPU cycles, you could well end up becoming agnostic as to whether the setup is used for "pure" 2-channel music or "processed" HT flash and sizzle.
     
    Last edited: Jan 1, 2018
  10. enginedr

    enginedr Well-Known Member

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    Distributed bass video .
    I have a distributed bass system 4 REL Q201e subs controlled by a DSPeaker antimode 2.0 ohm 004.JPG Bass is the soul of the music
     
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  11. bimasta

    bimasta Super Member

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    I thought one sub sufficient until I got a second — two of the musicians changed their positions by several feet on the stage, and the audience grew larger. Of course the subs should be identical, but different subs still work okay. I'm currently used two pairs of subs, each pair matched, but not to the other pair. One pair self-powered, one pair passive. "Distributed bass" I guess, but without mics to optimize position, nor DSP. Amateurish I guess but sounds pretty good if I set the level right by ear. And since I have the gear, I'd rather use it than take up limited closet space — I can use that space to hide other clutter.
     
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  12. z-adamson

    z-adamson AK Subscriber Subscriber

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    The problem with mixing subs last I checked is phase interference due to two non identical drivers.

    Some frequencies will cancel out, others will not
     
  13. musichal

    musichal poet emeritus Subscriber

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    I think that, even with identical drivers, phase interference is inevitable. Don't know with certainty, but it's what I think - I am no acoustic expert. My probably flawed understanding is that a room will have areas of rarefaction and compression which I believe we have all experienced (eg: modes, applicable to a single speaker and dependent upon placement, room size and other factors) and that any two drivers operating in the same room and reproducing sound in the same FRange will additionally have phase cancellation and enhancement based on their distance from one another and wavelengths of the frequencies reproduced which coincide with that distance, or multiples thereof, with complex interaction within said acoustic environment. The science of it is above my paygrade, but that is a part of my feeble comprehension based on things I've read.
     
    Last edited: Jan 2, 2018
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  14. motorstereo

    motorstereo AK Subscriber Subscriber

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    I had 2 identical subs in my main rig a while back and found it to be more hassle than it was worth to get them to integrate the way they should. Granted I only went by my ear but those same ears told me where the extra bass was coming from and which sub was a just a touch louder depending on where I was standing. I found myself constantly fiddling with the damn things rather than listening. It wasn't long before I went back to a single sub which was better than 2 and a couple months ago I pulled the single out which to my ears is better still.
     
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  15. musichal

    musichal poet emeritus Subscriber

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    Last edited: Jan 2, 2018
  16. Todd Dodds

    Todd Dodds AK Subscriber Subscriber

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    Oh, man..."...enhanced for refined behavior." !
     
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  17. Mister Pig

    Mister Pig Pigamus Maximus Subscriber

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    Should be quite interesting. SVS makes a quality product at a reasonable price.

    Regards
    Mister Pig
     
  18. nyhifihead

    nyhifihead Well-Known Member

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    this is an interesting theory as long as gain can be matched and LF extension is close you could get any 2 subs frequency response to "match" with help from the digital domain

    it would be far from seamless but this poses a good solution for those trying to upgrade to stereo subwoofers with a single discontinued/unavailable sub


    my LF is a constant work in progress. I found in room linearity was the best with the subwoofers diagonal, they are in stereo not sure how much "imaging" is taking place though because placement was for freq linearity.

    current setup

    [​IMG]

    It would be interesting to try something like this- mid wall front/back distribution. Much documentation says this is excellent. I'm curious how LF stereo imaging would be with a setup like this- I may have the experiment with this I will need dollies for 18s
    [​IMG]
     
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  19. motorstereo

    motorstereo AK Subscriber Subscriber

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    Nice looking small footprint subs:thumbsup: Are you planning on putting your new mains on top of them?
     
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  20. musichal

    musichal poet emeritus Subscriber

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    No, that would put the tweeters too high for my ears from the recliner. They will need to reside beside the mains, which does put them nearer the corners than I'd like, maybe. I don't have the luxury to place them just anywhere for ideal response, but have used various subs (singly) in those spots that worked well to my ear, and most people who've changed from a single to dual find that even better. Should work out very well.
     

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