Dual versus Single Subwoofers - Which

Discussion in 'Archived Threads 2001-2004' started by Myron, Oct 31, 2002.

  1. Myron

    Myron Agent

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    I've read a lot about using subwoofers and so on as to how the lower frequencies are not localized. Yet, I've seen in limited hearing and on some threads how having two (or more) sub-woofers improves the overall bass response and bass feeling.

    For HT use and for instrumental classical music, especially Pipe organ music, would people recommend a single say $2000 sub-woofer or dual $1000. (We have a semi-limited budget) so we can't go for dual 2k receivers.

    Bass is very important to us, especially the 20-40hz area. One of my prime test CD recordings for listening to speakers is a recording of the Canterbury England church organ. On decent sub's you can hear the individual pedals. No sub or poor subs mush the tones up.

    Plus at this point, I'm leaning very strongly towards having 4 of the Def Tech 2002s or 3000's with their integrated sub-woofers for my L/R and L/R surround speakers, in which case I'm not sure I'd even need separate sub woofer(s). I just don't know.

    Myron

    Myron
     
  2. Dustin B

    Dustin B Producer

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    Those towers won't do justice to the bottom end of a pipe organ at all.
    As for the dual sub thing. Placing them in the same place gives you 6dB of extra headroom across the board. This should answer your other questions about sub placement.
    http://www.harman.com/wp/index.jsp?articleId=122
    In the less than $2k price range I'd think a pair of SVS 16-46 PC+ or CS+ subs would be a great option. Not many other commercial subs out their with a tuning point that low.
    Give this a look to though. If you can do it I can't think of a better option for what you want then what could be done along these lines with a $2k budget (would even allow several $100 to pay a carpenter to install the manifold if you can't do it yourself).
    http://f20.parsimony.net/forum36475
    Either way, also look into get a parametric EQ.
     
  3. mark rush

    mark rush Stunt Coordinator

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    A little more info on how big your room is, how loud do you play your music, and do you want to FEEL the bass?
    Mark
     
  4. Mike Ford

    Mike Ford Extra

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    One of the advantages of a sub is that very often the best location for the sub and mains are different. Building a sub into the mains throws that advantage away.

    I personally still fall in the ONE and only one sub school, but I have to say the issue makes me nuts,and that having two subs does offer more flexibility. From a practical standpoint subwoofer quality takes a fair amount of money, so in most cases as you walk along the path of spending more money the first stop is a single sub that has both the quality you want and plays loud enough to suit you. The next stop is twice as much money for two of them. Unfortunately there is rarely a stop for half price same quality just a few dB lower output.
     
  5. Dustin B

    Dustin B Producer

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    Hehe, an infinite baffel is such a stop (except it will go really loud and really low [​IMG]). But not many people can or are willing to do them.
    8 Dayton 15" IB drivers and a decent pro amp will run you less than $1500. Then all you need is the manifold. If almost 20L of Vd can't keep you happy, you either have a huge room or are one sick puppy. This sub will also be able to do some serious justice to deep pipe organ stuff.
     
  6. Ronald Volkman

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    Myron,

    I like pipe organs also and I use a single 16-46 PC+. I don't know how big your room is or how loud you listen, but it's my impression that organ pedals require deep extension, but maybe not as high output as say, a large explosion. Like 18hz @ 105db versus 18hz @ 115db, but YMMV. Having said that, I have a single PC+ 16-46 in a 13 x 19 ft room that opens to another 13 x 17 ft room. On a CD like Reference Recording's Pomp & Pipes, the 18hz pedals feel like they're going to lift the chairs off of the floor.

    Ron
     
  7. Chris Tsutsui

    Chris Tsutsui Screenwriter

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    2 subwoofers increase the SPL of one sub by about 4-6 decibels. If used as L/R then the subwoofers create a center bass sound stage as well (for the higher frequencies the sub plays).

    I am now a believer in that subwoofers can play noticeable directional sound. It is because of the crossover slope which causes the sub to play frequencies that can be localized. I noticed this during music where some of the bass sounded to come from one of the subs. By adding an identical sub to the L/R solved the problem.

    Position is key with 2 subs. Adding a 2nd subwoofer with both in the corner will add more SPL and not really affect response. By separating the subwoofers to the left and right it will affect the response and possible cancel out odd order width modes.

    As for improvement of quality with 2 subs over 1 I am not sure. Bass is the region where I find the least amount of detail which is why I stress response and output more.
     
  8. RichardH

    RichardH Supporting Actor

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    Definitely get as much 16Hz tuned SVS as you can afford, and I highly doubt that you'll be disappointed. You might even be fine w/ a single 16-46 PC Plus depending on the room and volume.
     
  9. Haru

    Haru Stunt Coordinator

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    when I have my two subs located together and running in mono, I CAN, WITHOUT QUESTION, identify where they are, within a 30° arc. I had always, always believed that bass is non localizable, but that simply does NOT coincide with my own expereince now that I have two subs.

    using them in mono, placed together, I am ALWAYS aware of where they are. Used in Stereo and placed symetrically in the room, they vanish, just creating a solid, enveloping sound.

    The only thing that I can think of is that the subs set off higher harmonics in the room at a level high enough to be perceptible and thus give a directional element to the sound. It may be specific to my listening room.
     
  10. Doug_NHT

    Doug_NHT Stunt Coordinator

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    I second everything that Haru has stated.
     
  11. Bill Mullin

    Bill Mullin Stunt Coordinator

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  12. Dustin B

    Dustin B Producer

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    Chris is saying that in comparison to a single sub, a pair of subs will be capable of 4-6dB more output over the frequency range they play.

    In a perfect coupling you gain 3dB from doubling the cone area and you gain another 3dB from doubling the input power. For an ideal total of a 6dB increase. If the subs are placed as close as possible together you should see very close to this.
     
  13. Bill Mullin

    Bill Mullin Stunt Coordinator

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  14. RichardH

    RichardH Supporting Actor

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    That's almost correct. If you were doubling 2 speakers that were outputting 1kHz, you would get a 3dB increase. The reason you can get more than 3dB (like up to 6dB) w/ the dual subs is because the distance between the subs is significantly less than the length of the wavelength they are both reproducing. You kind of get to "cheat" physics in this case. This is what's known as "coupling" and it's also the reason why at concerts you see all those subs stacked on top of and next to each other. It allows them to play louder and go lower than if they were all spread out.

    You do not get 3dB for doubling the cone area and another 3 dB for doubling the power. e.g. if you have a receiver putting out 50w, you will not gain 3dB just by hooking up double the speakers.
     
  15. Dustin B

    Dustin B Producer

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    That's news to me [​IMG]
     
  16. Chris Tsutsui

    Chris Tsutsui Screenwriter

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    I don't think 1khz is in the frequency range most subs play but I still get your point Richard.
    Still, the best way I figured it out how much dual subwoofers really added was to actually experience it first hand. Even with the subs separated by something like 6 feet I still got a gain of 5-6 decibels over just one subwoofer.
    About localiziation... What I believe is that bass is non-localized at only deep frequencies. Even with 2 subs the localized bass will not vanish but instead create a bass stage between the two subwoofers which may very well sound the same as having a single sub in that same location. Sure the localization of bass is not where the subwoofers are but it will still be there.
    Perhaps a dipole subwoofer will help in that field.
     
  17. Chris Tsutsui

    Chris Tsutsui Screenwriter

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    In an anechoic environment you gain 3 decibels from adding a second subwoofer. I thought this was because you are essentially doubling the acoustic power which then equates to a 3db increase.

    Say you have 1 sub with 250 watts outputting 113 decibels at 1 meter in an anechoic chamber. Take 2 of the same sub and pump 125 watts into each of them and you should still get 113 decibels.

    Take one of those subs and corner load it for extra gain, and lets say it adds 3 decibels making it play 116db with only 250w. (Which is the same as doubling the power)

    Add an identical subwoofer with the same power and also corner load it and you should get another 3 decibels of gain which would be 119db.

    Take both subwoofers and put them together and acoustic coupling should add 3 decibels making 2 corner loaded subwoofers with 250w each theoretically capable of 122db.

    This is just stuff I came up with so please correct me as I like to make assumptions and don't mind if I'm wrong. I know there's a lot of factors involved in real rooms, I'd just like to know what's the maximum 2 subs could theoretically play if corner loaded and coupled over just one of the subs.
     
  18. Dustin B

    Dustin B Producer

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    I wonder if the localization of the sub also isn't partly a mind trick. Seeing the sub in the corner and knowing what it does can effect your perception. Then having a sub on either side of the room evens out this perception.

    Would be a difficult blind comparison to setup, but I'd be interested in seeing if you could consistently tell two subs in one corner from two subs in opposite front corners when you can't see them.
     
  19. Mike Poindexter

    Mike Poindexter Stunt Coordinator

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    Go find yourself a used pair of Infinity IRS Betas. They will be absolutely light years ahead of the Definitives and you will not need a sub. They are flat to 15Hz, can put out massive sound and the bass tower is seperate from the upper frequency panels. You have much better options for placing and they will set you back about the same as a new pair of Def Tech 3000 and a single sub.
    I have a picture of them here: (they are the surrounds)
    http://www.avsforum.com/photopost/sh...at=500&thumb=1
    The best choice is always the have speakers that don't need a seperate sub.
     
  20. Haru

    Haru Stunt Coordinator

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    Dustin,

    I am 100% sure that its not a mind trick. in my two subs, when the auto-turn on feature activates, the two subs do not turn on exactly simultaneously. One turns on a split second after the other. there is a gentle, muffled thump when the subs turn on. Each time, I can, without fail, tell which sub came on first. Its quite likely that the cone is producing SOME output at 100Hz or more, or maybe even during regular playback there are high harmonics in the cones themselves, but the point is that I KNOW where the subs are.

    Once, when I had them both sitting in the corner, I was thinking about this business of hearing them in a corner because I know they are in a corner. So I tried a trick. I played a DVD at my standard level, and then turned off the amps, which killed all the speakers, leaving only the subs running. I then stood in the middle of the room, closed my eyes, twirled in place. THen with my eyes still closed, I held out my right hand, to point where I was hearing the sound from. I repeated many times. I got within a few degrees of arc without fail. And each time, the twirl had left me disoriented enough that I had no clue to where was what, EXCEPT the sound of the subs.

    ANd I know its not just my subs either. A buddy of mine bought a PW-2200 and we spent a lot of time trying to find a place for it so that it's location would be completely transparent. I was never satisfied that the single sub wasn't producing a lumpy sound with the 1/4 of the room with the sub in it sounding heavy and lumpy.

    I wonder if it has to do with the tactile sensitivity of the human body. Perhaps I can feel the pressure pulsations on my skin, in my sinuses (they pick up low sounds better than the ear drums), and maybe in my cochlea. Maybe the bod (maybe mine) can detect the direction of travel of a pressure wave by discerning the delay between the time it affects various parts of the body.

    Heck, I am only speculating. All I know is that subwoofers are NOT non directional in my expereince. ANd believe me, I am not golden eared. I do not hear difference in the sonic characteristics of cables, stands, amps, CD Players, etc.

    But subwoofers are NOT non-directional for ME.
     

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