Bass non-directional - Fallacy?

Discussion in 'Subwoofers' started by eL-ZilCHo!, Jan 31, 2009.

  1. eL-ZilCHo!

    eL-ZilCHo!
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    I have heard it said that one should not be able to localize a sub.

    Is there any truth to this or is it a hideous lie made up in order to keep me tweaking!?

    Have I been "blessed" with canine-like hearing?

    No matter what I can tell where the sub is, no mater where it is, what level its set as - even really low, or what crossover is used. I was at the Manchester hifi show this morning and the few rooms with subs in I could, again, tell where it was. Am I a freak?

    This is the curent response in my room.

    [​IMG]

    Does that shed any light on my problem? Crossover is at 80Hz

    The sub is an SVS SB12+ so its a fairly high quality unit.
     
  2. RODCULL

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    Perhaps you're feeling it (so to speak) rather than hearing it?!
     
  3. ResidentDeagle

    ResidentDeagle
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    well, for instance when you walk out of the room you can tell there bass coming from a certain direction but when immersed you shouldnt be able to tell. especially at high vollage.
     
  4. The-One

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    I don't know about your original question. But I have to compliment you on your SB12+ in room response curve, it look really good. Espeically how the SB12+ actually goes flat down to 20hz.
     
  5. eL-ZilCHo!

    eL-ZilCHo!
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    I don't think so, its at all volume levels. The sub is positioned towards the left and I can hear it clearly in my left ear.

    This is always said, but for some strange reason I can always tell. It is perhaps a room issue.

    Does no one else have this problem. It sounds good on the whole, but it is quite annoying. I had this problem with my old sub also, even when positioned between the main pair, as it was for most of the time I had it, I could tell it was there. During deep bass moments it would (for want of a better word) collapse the stereo image inwards and downwards towards the sub, it would be very obvious it was the sub producing the sound.

    Perhaps I'm just sensitive to the harmonics or something - not entirley sure.

    It surprised me how deep it goes, rooms pretty small though. I only had to EQ out a small 60Hz-ish hump and it produced a natural house curve. It makes a hell of a difference though, really rattles the room when needed.

    If i could sort out the directionability (probably not a word!) I would be more than happy.
     
  6. skydivemacca

    skydivemacca
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    I'm just like you, i can pin point a bass source in any room i've been in. Much to the disgust of many show room sales people too I might add...

    Them "actually, no one can pin point bass"
    Me "um, yes, I can"
    Them "prove it"
    Me "really, is this necessary?"
    Them "close your eyes and point to it then"
    Me <sigh> "ok, it's over there"
    Them "you looked"
    Me "No, i didn't"
    Them "Right, let's try again..."

    This particular scenario continued 6 or 7 times (they had a lot of sub units in the demo room), sufficed to say i managed to persuade my dad not to buy a Bose system.

    Guess it comes from years of looking after my hearing (a huge fan of ear plugs) and spending a lot of my life as a sound engineer / pro tools op.
     
    Last edited by a moderator: Feb 1, 2009
  7. Knyght_byte

    Knyght_byte
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    A lot of bass is directional to people with sensitive hearing, but when these tests are going on, are any of you trying to pinpoint when only a 20hz signal is being emitted? Or are you just trying to pinpoint it when the speakers are turned off? Dont forget for music or .1 of a 5.1 track, the sub will be playing stuff up to around 80hz which is easy to locate.

    If you are locating a pure 20hz signal, its possible it is your body locating it more than your ears. I have very sensitive level of touch and skin pressure, consequently I can tell if one foot felt the impact before the other or the toes before the heel etc, I wouldnt be able to pinpoint exactly where the sub is but I could give a vague area (ie that wall or that wall etc). Its a very minute delay but its more than possible for the human brain to distinguish this. Perhaps you should try sitting on a few mattresses and cover yourself in cotton wool when performing the test to be sure...hehe.
     
    Last edited: Feb 1, 2009
  8. eL-ZilCHo!

    eL-ZilCHo!
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    I've never tried locating it with tones to be honest, just when everything is playing normally, maybe I'm just sensitive to it.

    Might try some tones and see if I can locate it.
     
  9. Nimby

    Nimby
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    This is a situation where the main speakers may be undersized. Despite the 80Hz crossover there remains a trough in the response between the subwoofer and the main speakers. The speakers can't go low enough to fill the trough and the sub is unable to fill the trough because it is rolled off by the crossover slope.

    Or, the subwoofer is simply playing far too loudly relative to the main speakers. A common situation at dealers and shows, I would imagine.

    Or, the subwoofer itself is producing lashings of harmonic distortion which are drawing attention to it.

    In an ideal situation the bass is "steered" by the main (and surround) speakers. The bass should move freely around the soundfield to match what is seen on-screen. e.g. Helicopter arriving over the right shoulder as in the Dolby pre-film trailer.

    Looking at your nice response curve and knowing the quality of your subwoofer most of these options can probably be discounted.

    How big are your main speakers?
     
  10. eL-ZilCHo!

    eL-ZilCHo!
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  11. Nimby

    Nimby
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    The speakers are unlikely to be the problem with frequency overlap then.

    Given an ample cross section of AV bods perhaps one person who can identify the source of deep bass may be a statistical possibility.

    Don't you get any sense of bass steering at all? Like bass guitars playing on the other side of centre from your subwoofer position in stereo?

    It might be fun to download some LF tones and see how low you need to go before you can no longer identify the subwoofer as the source.
     
  12. Isco 3

    Isco 3
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    Ported subs do tend to generate some extra noise by the way. All subs in general do have mechanical noise, so it is best turning the driver the other way and put absorptive material on that surface.
     
  13. eL-ZilCHo!

    eL-ZilCHo!
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    well I've been having a play. THX demo disc, bassy bits of films etc.

    I'm not entirely sure but i thik it may be exciting the floorboards/ radiator/ something else over there, and that is what I'm hearing.

    On the whole it does blend in. bass sounds are indeed steered around the room fairly convincingly.

    However the deeper the sound the more obvious its placement is. Which goes completely against convention. Hence my thinking it could be my less than sturdy house to blame.

    Plausible?
     
  14. Nimby

    Nimby
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    Makes good sense, actually. :smashin:

    The lower the frequency, the more structural vibration, the more rattles you'll get.
     
  15. m4rky_m4rk

    m4rky_m4rk
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    The detection or not of the source of low frequency sound is down to the basic physics of waves.

    Amongst many other things eg room reverb, the ability to localise the source of a sound depends on how far apart your ears are. The calulations are complex and there are many ways used by the brain to localise sound.

    It boils down to the fact that big heads with a greater distance between the ears are better at localising low frequency sounds.

    The shape of the head is also important. It's better to be assymetirc ie lop sided features. Maybe the stuff between the ears is also important too.

    I did a bit of googling on the subject and came up with this

    Sound localization - Wikipedia, the free encyclopedia

    Not the best link but maybe someone has something better. There's a huge ammount of science and a lot of talk on the subject but not much in the way of numbers.

    Part of the reasoning is simliar to why very high frequency sound is used for medical imaging and by bats. High frequency means small wave length and the ability to image, localise, smaller features.


    :clown::clown::clown:
     
    Last edited: Feb 1, 2009
  16. berkeley384

    berkeley384
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    eL-ZilCHo! I share your pain mate

    My Sub is to the right of my TV and no matter what I do its location in my room is quite obvious.

    It was obvious with large floor standing speakers with the cross over set at 60Hz, its no more obvious now with the smaller speaker but as you would expect these were never going to make things any better

    I can sit in my main listening position and play sub tones from 16Hz upwards and near enough all the way through the range the direction is obvious .

    For me though Im convinced that my problem is caused by my room modes.

    Whilst on both the left and right side of the sofa I have a nice even response curve, its louder on the right than it is on the left. E.g at 50Hz on the left side of the sofa the SPL meter registers 73db , move the Spl meter to the right of the sofa and 50Hz registers 78db


    I suspect that sitting slap bang in the middle of the sofa, my right ear hears the sub louder than my left giving the effect of directional bass. Possible ??
     
  17. eL-ZilCHo!

    eL-ZilCHo!
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    You saying I've got a big head? :D

    berkeley384, at least its not just me.

    Could be down to the way the sound bounces around the room I guess. I don't know, think its just something I'm going to have to put up with.
     
  18. eL-ZilCHo!

    eL-ZilCHo!
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    I've never thought of that, could be on to something. The sub is EQ'd from the central position but there could be something awry either side of my head, there's probably no way around that either.

    hmmm, i feel an experiment coming on...
     
  19. paulst10

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    I also thought it was a right-sided thing once, but it doesn't seem to be the case anymore, I still have the sub to the far right of the room but I can only localise it some of the time now whereas before during my more experimental days and in a different room I always thought the right-sided theory to be true :(
     
  20. j0hn

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    :rotfl: that read like a Monty Python sketch. :smashin:

    My sub is positioned to the right of my seats so its in the rear, crossed over at 100hz. With music I can sometimes hear it but its so miniscule I can shake it off just as quick as I noticed it. The other day I watched Batman Dark Knight and I could notice real easy. My sub is same as yours sb12+

    I used to hear my other subs and also this one sometimes when it was at the front of the room. I used audysee to set this one. No PEQ. It blends really good! Maybe its an intrigation problem that your hearing when you can locate others at demos etc? I know I can.
     
  21. Maxamus

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    My sub is in the corner as you can see:

    [​IMG]

    I've never been able to tell so far the bass is coming from where the sub is positioned. It seem to come from all directions and fills the room.
     
  22. eL-ZilCHo!

    eL-ZilCHo!
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    Well I'm nearly 100% sure its a room issue, I did an experiment last night were by I gradually turned the sub down whilst listening to music and the lefty bass was there at all volume levels, up to and including being turned off completely!

    So its either a room issue or my, frankly unreliable, brain is playing tricks on me again!

    Its probably something I'm going to have to live with until I move. Won't stop me having more of a play with it though. I will have to revisit the EQ anyaway, just to make sure, as I found out last night that I had to raise the level of the sub approx 5db post EQ to get a 75db level set. So I could locate it and it was well under the level it should be... wonderful!
     
  23. cribeiro

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    :confused:
    I suggest that you swap right and left channels between source and amp. Play the music again. Where is the bass now coming from?
     

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