Maybe, we have all been setting our systems up WRONG!

Discussion in 'Archived Threads 2001-2004' started by John A. Casler, Feb 19, 2002.

  1. John A. Casler

    John A. Casler Second Unit

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    Hi All,

    Recently we had a thread about setting up a two sub system and I suggested having one sub in the front corner of the room and the other set up out of phase in the opposite rear corner (my current set up) which made it a "push-pull" system.

    There was much speculation and even some measurements taken but in the end nothing much was settled.

    It occured to me that several years ago I saw an article (with pictures) of the "perfect sound room".

    In this room, the front wall actualy did not exist. As you sat facing the speakers, the area behind them was a rather deep V.

    In fact even the ceiling slanted down and a "HUGE" subwoofer sat at the back of this V, making the walls almost like a big horn loading system.

    Now there was more to this room, like it was made out of very thick concrete walls/floors and reinforced ceilings, it had all kinds of sound treatments and reinforcements, but the one thing that stood out was this sub placement at the back of the V.

    What if we set our rooms up (forget we have wives for a second) with the sub in the corner and the TV in front of it and the room is "diagonally" set up.

    This could offer some interesting possiblities with the surround speakers and other issues, but it would seem that subs or "stacked subs" would really be benefitted by this arrangement. We all know that as we walk into the corners of our rooms, the bass is substantially louder so we may even want to sit more in the opposite corner.

    Maybe this will cause the leanest bass in the center of the room. or maybe it would big BIG????

    Since I'm single, I have been toying with the idea of this kind of set up, but before I start moving things around, I thought I would throw it out to the group.

    Any comments?

    John Casler
     
  2. Michael Mohrmann

    Michael Mohrmann Screenwriter

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    I imagine that a diagonal system placement might work provided that the room were square or nearly square to balance the room reflections. A diagonal placement in a rectangular room would seem to be prone to an inbalance of sound (specifically for the non-bass).

    Michael
     
  3. Kevin C Brown

    Kevin C Brown Producer

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    John- I'm guessing I'm not understanding completely your proposal.
    It'a already known that usually you get the most output from a sub in a corner, diagonally arranged or not. (Flattest response is usually 2/5 or 1/3 down the longest wall.)
    With that being said, I have my sub in the corner, but my system is arranged along a long wall (speakers, TV, equip rack etc.). Futon/sofa is maybe 65% back into the room. *Not* against the back wall. *That* is terrible for sound.
    A friend of mine does it in a corner, like you suggest. Now this is definately not scientific, but I think my system sounds better. [​IMG]
    Of course, I do the Avia balanced levels thing, properly adjusted phase, eq on my sub, etc. He has ... a Bose system.
    There is software out there for optimization of speaker placement in a room. I wonder what that software would say about a diagonal arrangement?
    Also a Q: two subs in opp corners, 1 out of phase. That doesn't seem right to me. If both subs were truly out of phase at the sweet spot, then you'd be cancelling there and get no bass! [​IMG]
     
  4. John Garcia

    John Garcia Executive Producer

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    Due to a door and heater vent on my front wall, I have my system on a slight diagonal, facing right corner to left, with the sub in the front right corner. The couch is about 3/4 of the way across the room, with all 4 speakers at ear level and the center on the TV. Bass is very prominent, however I do get nulls and strong spots in the room. Unfortunately, on one end of the couch, nearer the wall, is a strong point. On the other end of the couch, a null. Still having to adjust to find the right spot/angle for the sub to alleviate this, though the "V" location of the sub foward firing into the room, seems to help the sub out quite a bit. My sub has a remote, so I have to have it face front (or use a repeater).
     
  5. John A. Casler

    John A. Casler Second Unit

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    Kevin,

    Well I'm talking about setting the room up like a diamond, rather than a rectangle. It is a whole different paradigm.

    As far as your question about the "two" subs, it does not cancel or form a null in the middle. Quite the opposite. If we have two subs and both are in phase, if you are in the exact middle they are pushing against each other. As one woofer is pushing out, the other working against it.

    If you had a bubble between two people and both were blowing on it, the forces would meet and balance each other and the bubble would not move (in the exact center in a perfect world)

    If one person blew when the other person inhaled, the bubble would have the most action. It would be sucked and blown all over the place.

    This is what happens, (or so I have been told)when you set your subs up to "push-pull".

    I think what you want is the greatest amount of air moving at the same time. Although there was subsantial debate when I mentioned this earlier, the conclusion, (by the science types) was not unanimous.

    This concept however is not related to the "diagonal room" set up mentioned in this post, although I might try it "if" I do the diagonal set up.

    John Casler
     
  6. John A. Casler

    John A. Casler Second Unit

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    I just noticed that I only received replies from members in California????

    Is it because we think differently? Are we more adventerous? Or are we just a bit off center?

    Let's see if there are any of the other 49ers looking at this heresy.

    John Casler

    (almost a native Californian, I arrived here shortly after Cortez....... Billy Cortez, he had the blue van in front of me)
     
  7. Kevin C Brown

    Kevin C Brown Producer

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    John- (dang that Gruden... [​IMG] )
    I hear you about the subs, but...
    Here's how I adjust for "phase":
    I would measure each sub's response individually slightly below, at, and slightly above the crossover pt.
    Then make sure that both together measure "louder" than each individually.
    So, I think we are actually saying the same thing, but differently.
    Sounds like if what you say is true, I would have to adjust one sub 180 deg out of phase to the other to get that maximum response in the sweet spot.
    Basically, you're just shooting for constructive interference with both subs there.
    But I would do it by measurement, not just by putting 1 sub out of phase with the other. But sounds like you did do that...
     

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