Should Dual Subwoofers Be Identical Models?

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

  1. soundmig

    soundmig AK Subscriber Subscriber

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    The post says bass E ... If they are listening to bass guitar playing a low E then what they are localizing is the overtones at much higher frequency. If they are playing a straight 41 Hz tone from a tone generator, then they may be localizing based on harmonics (from distortion produced by the woofer driver). I highly doubt that anyone can localize a pure 41 Hz tone - I could be wrong, but the wavelength is too long to localize to any degree in a typi
    Nice subs!!! These should sound great. Good price too!
     
  2. musichal

    musichal poet emeritus Subscriber

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    I understand just what you mean about using a tone generator and getting locatable distortion, having done that many times using 40hz with bookshelf (and other) speakers. Whether the well-reproduced pure tone could be located I figure may depend on a variety of factors, especially environmental, and probably the listener's hearing and experience. I know it isn't easily detected.

    As for timbre differences between instruments, harmonics occur at higher frequencies, sure. However, there may be other natural resonances produced by an instrument that do occur at slightly higher frequencies (but not necessarily multiples of a fundamental note) that fall within a subwoofer's range that can act as cues, too. Maybe?

    Thanks for the positive comment on the subs, too.
     
    Last edited: Jan 2, 2018
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  3. Grenadeslio

    Grenadeslio Active Member

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    You're going to like running paired subs set up in stereo.

    I'm currently running two systems with subs, one with two as a stereo pair with the main's on top, the other with a single sub. Now I'm the first to say two is better than one of equal quality, but one great sub can shame two average subs.

    If worried about localization running one sub either center the sub between the mains and run the mains full frequency, or set the sub in either front corner with the sub firing across the front wall. Of course this last method necessitates a front firing sub lol.
     
    Last edited: Jan 2, 2018
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  4. awillia6

    awillia6 Active Member

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    Could you please explain how your two recommendations address localization concerns. Wouldn't running the mains full WITH a sub generate too much output in the freq range the two speaker types can each produce?
     
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  5. Grenadeslio

    Grenadeslio Active Member

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    Four decades of running multiple subs, beginning in automotive have given me the experience, try it you might like it.

    First, having the mains running full frequency without a sub is a start, imaging usually places the bass front and center, so if you're going to add additional bass wouldn't you think OFF center would be well, off center lol. With this setup, when the bass frequencies do move either left or right you still have the same spacial affect. If all of the lower bass frequencies are channeled to the sub, even if centered, this shift left or right won't occur leaving the soundfield flatter. There's a reason centered is often the recommended position for the sub, corner another if the sub needs further bass reinforcement.

    Now imagine if center placement isn't physically possible, diagonal in the corner might seem logical, but this never worked for me. But, if in the corner firing across the front wall the whole wall becomes the bass source and localization isn't an issue. I've used and recommended this method when only one sub is used many times and it's always worked well. Again, I'm referring to front firing subs only.
     
    Last edited: Jan 2, 2018
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  6. awillia6

    awillia6 Active Member

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    So much time, so little learned.

    "a start" Hmm...the request was: "Could you please explain how..." and the question was: "Wouldn't running the mains full WITH a sub generate too much output in the freq range the two speaker types can each produce?" In your haste to post your bona fides, you failed to provide any sensible explanation addressing the overdriven bass situation you advise others to create. Not good.

    "this never worked for [you]" Hmm...I don't wonder given walls magically becoming "bass sources" which apparently HAS "always worked well [for you]".

    Believe, I'll pass. No further "explanations" needed. Thanks anyway.
     
    Last edited: Jan 2, 2018
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  7. charles 1973

    charles 1973 Super Member

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    "Should Dual Subwoofers Be Identical Models"
    -------------------------------

    It depends on your goal. Since you have stated music was a priority, I would suggest using 2 identical subs with proper bass management, like in AVR's, (or with a sub with a high pass filter. Not all subs with speaker in & out have them). The reason being to produce a more effective distributed bass and ease of correct implementation To get the most out of 2 different subs would require the use of a 2 step X-over and very carful set-up.

    Personally I find one high quality sub properly set up (using the bass management of an AVR) produces very satisfying results for music and HT. Not only does it add the very important bass fundamentals to music for my smallish (14" high - 5.5" woofer) bookshelf speakers in a large room, But by diverting the bass below 80 hz from them totally transforms their sound. Imaging, Soundstage, Micro-dynamics, power handling are all improved. When combined with a proper sub and bass management, Most decent bookshelf speakers will also produce the scale of a large floor standing speaker, But with deeper, cleaner bass that we can control.

    What surprises me is when I put the sub 20' away from my bookshelf speakers, I could not hear the sub at all standing right in front. Yet listening to the speakers it absolutely sounded like they were producing the bass, The kind I might expect from a very good set of floor standers.

    In a smaller room, Many bookshelf speakers today can be quite satisfying without the need for a sub, But bigger rooms seem to require more bass (as in displacement), not necessarily much deeper.
     
    Last edited: Jan 2, 2018
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  8. musichal

    musichal poet emeritus Subscriber

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    Well, my first goal would be not to replace my little integrated amp with an AVR.
     
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  9. awillia6

    awillia6 Active Member

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    To a screwdriver being used as a hammer, everything looks like...uh, well, um, wrong. Everything looks just wrong.
     
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  10. charles 1973

    charles 1973 Super Member

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    Of course. That's why I mentioned sub's with a high pass filter. If you can't find a sub with one, You can use one of these between your amp and speakers.

    https://www.parts-express.com/80-hz-high-pass-8-ohm-crossover--266-458


    They have a few to choose from, so pick one that best suits your speakers (impedance and LF extension - 80 hz is popular). The important point is to keep the low bass from the main speakers.
     
    Last edited: Jan 2, 2018
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  11. robert_kc

    robert_kc AK Subscriber Subscriber

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    The Oppo universal players (e.g., UDP-205, BDP-105, BDP-95) feature "bass management" - i.e., a built-in crossover, and a connection for a powered subwoofer. With Oppo's bass management, the low frequencies are off-loaded from the main amp and speakers, thereby facilitating greater overall dynamics.

    IME, subwoofers can be a PITA, because audio recordings and movies are not consistent in bass content. (I dislike intense LFE in movies. I have no interest in recreating the rumbling of an earthquake in my listening room; I don’t want to be assaulted by my hi-fi system.) Because of the wide variance in bass content in music and movies, my opinion is that a remote control is a useful feature for a subwoofer.

    I understand why some people give up on subwoofers. Nonetheless, I have them in 3 of my systems, because one of the things that strikes me when I attend the symphony is the power of the low frequencies. Subwoofers help to deliver the dynamic impact of a recording of large-scale orchestral music.

    In my basement system I have an SVS SB16-Ultra, and a Klipsch R-115SW. I put the SVS SB16-Ultra on the left because it probably has more deep bass output, and my local symphony has the double basses on the left. (I have the output of the subs adjusted so that the SVS SB16-Ultra does more of the “heavy lifting”.)

    This afternoon I listened to a Blu-ray surround-sound recording of Beethoven Symphony 7 on my basement system while I rode my exercise bike. No problems with delivering large-scale sound, considering two powered subwoofers (one 15”, and one 16”), and with LCR equipped with Klipsch RF-7II (each with a 1.75" horn-loaded compression driver, plus two 10” woofers), plus an RF-7 for the single rear. This afternoon I drove the LR channels with a McIntosh MX110Z / Scott LK150 (KT88 output tubes), and the center and rear with a Fisher KX-200 (7591). Did it sound perfect? No, but it sounded pretty good to me. (With tube amps driving the Klipsch, I realize warm, rich sound.)

    FWIW, my philosophy is “run what you brung”, and enjoy the music. :)

    Congrats musichal on your new subs. I’m certain that two 12” powered subs will handle any music, in an average size room, at reasonable sound levels. I hope you enjoy music for many years to come.

    Please keep us posted.
     
  12. donprice

    donprice Wound up workin' at a gas station....

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    This is a good example of non-directional bass. My HT (living room) system has the sub 6' to my left while the mains are 10' to the front. Turning the sub on and off (via the power switch) clearly results in the bass response of the mains increasing/decreasing despite the fact that I know that is not what is happening. Psychoacoustics are a powerful thing (and bass is non-directional below xx Hz).

    Anyone that has not experienced what Charles 1973 has described should try a simple experiment. Reduce your subwoofer crossover as low as it will go (50 Hz?) to minimize harmonics and then move it as far from your mains as possible. Then fire it up and turn the sub on and off and see what you hear. You've spent an hour reading this thread but this 5 minute experiment might actually prove something to you. Or not :rolleyes:
     
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  13. musichal

    musichal poet emeritus Subscriber

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    I'll continue with the 80hz filter already built into the Levinson, thanks anyway.
     
    Last edited: Jan 3, 2018
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  14. motorstereo

    motorstereo the wonder of it all Subscriber

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    Having done this exact experiment is just one of several reasons I pulled my 2nd 18'' sub from my main rig. Yes I could easily pinpoint it in spite of supposedly not being able to.:dunno:
     
  15. twiiii

    twiiii Super Member

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    If you are using 2 subs for a HT system in non symmetrical locations I don't think they would need to be identical. But they should have the same capabilities after being placed in their chosen position. So the least efficient unit would limited response would go in a corner to help match the larger one with extended range and higher out put capability placed away from corners or maybe elevated. I' don't like subs. So unlless they were used each with the L&R speaker to extend the range in the Stereo mode or to be placed to smooth out the response unobtainable by a single LFE speaker I don't think they need to be exactly the same.
     
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  16. musichal

    musichal poet emeritus Subscriber

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    Well, they will indeed be positioned symmetrically in the room, just outside the mains, so I anteed up for a matched pair, as you wrote - to extend range of a stereo pair, L&R. Seems the logical way to go.

    And this is why I sold the Khorns. The Silver 6 fit symmetrically in the room, but Khorns did not due to corner issues (built-ins and an extended fireplace hearth along one wall stood the L off the wall). And the room is a long rectangle with only one spot where speakers can go along a short interior wall (room approx. 14.5x29') putting the horns too close together, exacerbated by the Left stand-off in that regard, as well as not properly corner-loaded.

    I impulse-bought the Khorns. This time I bought with more forethought, and the system SQ improved. The six-inch woofers in the slender towers need some assistance, though. Subwoofers. If one is good, then two is better, right? (Using a single Polk now, until the SVS arrive.)
     
    Last edited: Jan 3, 2018
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  17. musichal

    musichal poet emeritus Subscriber

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    Amazon shipped one sub from TX, and it has just arrived a day early. And one from TN, due tomorrow. So one down and one to go. Not even opening the box 'til the other one is delivered.
     
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  18. awillia6

    awillia6 Active Member

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    Make sure you check them for serial number sequencing, sub-model designation variances, date and place of manufacture, etc. Coming from separate warehouses could mean the subs came from separate production batches and might have differences in internal parts, construction, and/or engineering even though the overall model designation remains the same.
     
  19. musichal

    musichal poet emeritus Subscriber

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    Same model from reputable company. If small variance, which keep, which send back? And almost sold-out, discontinued model likely all last run anyway. Should be close enough for gubmint work, at any rate.
     
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  20. MannyE

    MannyE Exterminate! Subscriber

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    Dude... if you have two different subs already that you got for free, then no. But if you're buying new subs... then absolutely. Why would anyone want to risk any mismatch if buying new?
     
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