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Line Arrays (split from KODA8 thread)

Discussion in 'General Car Audio Discussions' started by geolemon, Sep 2, 2004.

  1. geolemon

    geolemon Full Member

    Speaking of which though...
    I finally stuck one of the Tang Band 3" midranges in my little test enclosure (something like 9"x6"x4", and lined/stuffed with acoustic foam).
    The little sucker sounds amazingly good, particularly for such a ridiculous little speaker. Even gets very loud! It really would work great as a standalone speaker for a set of bookshelves.
    I think that speaker very well might be the candidate for the next line array project... would be very fun. B)
     
    geolemon, Sep 2, 2004
    #1
  2. hobbes26

    hobbes26 Full Member

    hobbes26, Sep 2, 2004
    #2
  3. PolkMM

    PolkMM Full Member

    how good are the RE re8s?
     
    PolkMM, Sep 3, 2004
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  4. geolemon

    geolemon Full Member

    I've got exactly the same ones you have... the TB871S's from CSS, the ones pictured with the phase plug.
    What purpose do the other speakers in your enclosure serve, if you don't mind my asking?
    Just curious, since the TB871S's have such a range on their own...

    My observances are basically the same as yours, although I haven't gotten much listening time in yet myself...
    Very remarkable, for a 3" speaker... it really does extend up near 20K, if not to it... but does sound a tad soft... not in output, but in tone... much like the sound of a stereotypical soft dome tweeter, compared to the stereotypical hard dome... and I also prefer the deeper detail of a good hard dome.

    Other than that, I thought it sounded very good pretty well all through the range. I was only powering them off my Yamaha receiver's outputs, no external amplification, and no processing... bass set to 0, treble set to 0.

    They don't have much bass... but for a 3" speaker, they honestly held their own, they really had very very good bass, for a speaker of this size!

    My intention is to find a speaker (honestly, likely this is the candidate) for a new line array install (like I did in my old Hardbody)... it'll hand off to a midbass driver somewhere around 200hz, and I'm sure they can go that low just fine... a nice steep crossover would keep them very happy, I'm sure.

    What I'm wondering is if I can employ something like a parametric EQ to dial out any anomolies, to really turn these into something serious, from a SQ-install perspective?

    It's intriguing anyway, it's certainly remarkable, for a little 3" driver. B)
     
    geolemon, Sep 3, 2004
    #4
  5. hobbes26

    hobbes26 Full Member

    Yup, top end wasn't great - just a bit on the soft side - I would have liked it a bit sharper. Low end is very good considering it's a 3"...

    No good for bass heavy stuff. Awesome on Sarah Mclachlan and her piano music.... and other music of the like.

    Maybe if I put a HP filter on it at ~80Hz....

    The bottom speaker on the unit is supposed to have a better low end than the 871S and not much of a high end - the Superelf design is (apparently) modified from an earlier version, which used two 871S's, to have better low end response.

    The 871S is actually within it's own little enclosure in the top (basically just a cup behind the driver), and the box is ported for the lower speaker. I'm not sure of the crossover frequency or slope - Bob from CSS didnt reply to my email (grr).

    Speaking of line arrays of the TB ilk... there's a pretty interesting discussion on them on the soundillusions site here --> http://forum.soundillusions.net/showthread.php?t=38445 mostly talking about the pros/cons of line arrays, but starting out as a thread on someone wanting to make a TB line array.
     
    hobbes26, Sep 4, 2004
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  6. geolemon

    geolemon Full Member

    I don't really visit SoundIllusions...

    And bear in mind, my "line array" is too near field (as would ANY car application) to benefit from the traditional benefits of a line array...

    ...rather, the benefits are what I stated here - my use of the term "line array" is a little loose in definition, because it's not a traditional line array, and the benefits are not that of a traditional application.

    Here was my first in-car line array (feel free to share it at SI):
    http://www.betteraudio.com/geolemon/Lineso.../Linesource.htm
    ...but please do disclaimer it as I have - because you simply WON'T be able to get the benefits of a traditional line array, in such near-field application. B)
     
    geolemon, Sep 4, 2004
    #6
  7. hobbes26

    hobbes26 Full Member

    I remember looking at that page a while ago... and not having studied line arrays too much, but from reading the thread at soundillusions, i'm kinda concerned about the phasing issues to be had from having two (or more) speakers mounted close together and playing the same frequencies (not the crossover frequencies as you mentioned in that page). In the near field, it's quite chaotic, since you're in the near field of two not-so-point sources - you move your head and there would be HUGE changes in the frequency response. If you could somehow make it so that exactly at the distance from your head, though, there was the perfect frequency response that you wanted, right there, I guess it could work.

    But an arrangement that has been shown to work, as they were talking in the CarSound forums a little while ago, was the D'Apolitto arrangement (MTM), but sideways - as done in the JL Mini with 5.1 surround (and the best part - the plasma screen in the hood!). In this way, the arrangement of the speakers helped to focus and beam the sound, so that the 5.1 channels would be more separated from each other.....

    (maybe we should separate this from the Koda thread)
     
    hobbes26, Sep 6, 2004
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  8. sandt38

    sandt38 Full Member

    I was thinking about that Hobbes. I want to find what track you guys are following on this so I can decide where to split it and what to title it.

    Chris and I spoke about arrays last night, and thylantyr asked about them on CAF HT where I posed my perspective. Chris and I also discussed typical MTM alignments and I voiced my opinion on the lack of imaging and collapsed stage, which I will also voice my opinion on.

    But before I do I want to see where you guys are taking this so I can split it accordingly, and not get too far off topic myself. ;)
     
    sandt38, Sep 6, 2004
    #8
  9. geolemon

    geolemon Full Member

    Like I mentioned, the goal isn't to work as a line array...

    If you have a line array [and are listening in the near-field], and you move your head around, you create phasing issues because you are changing the pathlength distances from each speaker to your head...

    With my line array that I built, great care was taken to actually phase align each speaker with the location of your head.
    That's the very purpose of the arc that the speakers are mounted to, and the string-compass that was used to draw the arcs. B)

    So - in that respect - very much different from a "line array". ;)

    If you hadn't yesterday, it might be worth another read - I believe I got into a good amount of detail as to why I did what I did...
    And if I decide to do it, another one in the Pathfinder, I'll be most likely phase-aligning those four Tang Band 3" fullranges on each door.
     
    geolemon, Sep 6, 2004
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  10. hobbes26

    hobbes26 Full Member

    But i'm not talking about having the speakers phase aligned with your head - yes, you can have them the same distance from your head, but there's the problem of having destructive interference between the two (or more) speakers themselves that creates the chaotic near-field that I was talking about. It depends on the frequencies you're having the speakers play, as well as the distance from each other, as well as the finite physical size of the speakers, etc....

    So the problem wouldn't be to just have the speakers all at the same distance from your ears, it's having them at the optimal distance such that even with all the destructive interference that's happening around you, you're in the right position to have the constructive signal that you want. And that's assuming that the sweet spot will be large enough for you to experience.
     
    hobbes26, Sep 7, 2004
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  11. geolemon

    geolemon Full Member

    That's the point of the experiment! :lol:

    The theory is (which differentiates from traditional [inherently] non-aligned line array) that the phase-aligned speakers will yield roughly universal constructive combination...

    While, at the same time, exploiting just what you are thinking is a detriment... ;)
    Which is, any signals sent off in any other directions but the direct pathlength to the head, WILL suffer the chaotic (I like that) and destructive combinations, and therefore degrade, while the direct pathlength sound will combine constructively...

    Essentially, two forces working towards the "common good". B)

    And very much different from the traditional [inherently] non-aligned line array. The key is in what is causing the chaotic degradations that you describe... the same phase issues that are being exploited for my benefit [by phase alignment, in my case by pathlength manipulation], in that project. B)
     
    geolemon, Sep 7, 2004
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  12. hobbes26

    hobbes26 Full Member

    Okay, I see...

    What about the pathlength differences between the right and left channels?
     
    hobbes26, Sep 7, 2004
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  13. geolemon

    geolemon Full Member

    Well, depending on how you look at it - no improvement over any other typical in-car system where you are sitting offset slightly to one side.

    But I do believe there is (or was :() some additional benefit, because imaging really was at least decent -

    One thing that I was would effectively also simulate with this, would be a point source that was located much farther away than where the individual components of my sound source were actually located...
    So, I believe that is why the imaging was actually better than what you might have with say, a typical custom kickpanel location - even though I really spent no time at all angling the drivers, rather just experimenting purely with the "line array" (I hate to use that term now, because of this thread! :lol: ) aspect of the thing...

    ...since I''''m also a firm believer in scientific methodologies - that is, manipulating only one variable at a time, so you can actually isolate it. :detective:
     
    geolemon, Sep 8, 2004
    #13
  14. hobbes26

    hobbes26 Full Member

    I believe there''s a term for this kind of source... not sure what it is though.

    There was a guy at the Adire meet this August who brought in a ''line-source'' that he had made with about twelve 2" radio shack drivers, except that they were arranged so that there would be about a 10'' radius, a ''('' shape, if you will. The ''sweet spot'' would be about 10'' away from this source. It stood about two and a half feet tall and something like 4" wide. I believe he had made those quite a few years ago. You could definitely tell the directivity of these things, and listening up close was very bad, but the sweet spot was quite good and you didn''t necessarily have to be so far away to hear the effects.

    But in-car, for me, I say that the cost of doing something like this (money and time-wise) is currently out of reach. I''d also need a sacrificial car to work on. ;)
     
    hobbes26, Sep 9, 2004
    #14
  15. geolemon

    geolemon Full Member

    Grand total I spent on my line array project (granted, there were many 'ghetto' aspects of it, in the interests of making it an experiment, as opposed to a full-on committment) was $260, plus a few deals and trades.
    Dont' fear the sawzall. :D
     
    geolemon, Sep 9, 2004
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  16. hobbes26

    hobbes26 Full Member

    I don't fear that. I just need a "junk" car to work on. Something that I wouldn't be afraid of doing that experiment in. Especially if something went awfully wrong.

    I also don't really have the time.
     
    hobbes26, Sep 9, 2004
    #16