Subwoofer Optimization Question

Discussion in 'Speakers' started by Neil McCaulley, Mar 1, 2005.

  1. Neil McCaulley

    Neil McCaulley Stunt Coordinator

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    Hi All,

    I have a powered sub with my system. For space considerations, I use a printer stand for my receiver to sit on top, and my subwoofer sits in the open cabinet area below. The stand is made of pressboard. There are no legs on it. It sits on the floor with its three walls (back, left and right) resting on the ground. The sub sits on the bottom shelf about 4 inches off the ground.

    I am wanting to purchase a nice A/V Rack to make it look a lot more presentable than it is now. My question is, should I have the sub directly touching the floor to get the best sound, or is having it elevated the way it is now the best option? Keep in mind that my home theater rests on a slab floor. No wood. Since the idea for the subwoofer is to push air outward and towards your ears in order to get that booming LFE, am I creating a pocket of air with it elevated off the floor? I am thinking that if I placed it directly on the floor, it would absorb some of the shockwave, thus reducing the effectiveness of the LFE.

    What is your opinion?
     
  2. John S

    John S Producer

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    With subs, experiementation in any given room with an SPL meter is always best. I have been shocked at results, only moving a sub as little as 6" in a given direction on the SPL meter.
     
  3. Neil McCaulley

    Neil McCaulley Stunt Coordinator

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    Typically, how much does a Sound Pressure Level Meter cost?

    So in essence, there is no 'right' or 'wrong' answer to my question? It is all subjective?
     
  4. John S

    John S Producer

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    It is all room specdific would be a better way to put it.

    I have not bought one in quite a while, seems like I paid $50 for my RS SPL meter years ago. It has come in handy 2000 million times since I purchased it though, quite handy for all sorts of quick tests.
     
  5. Neil McCaulley

    Neil McCaulley Stunt Coordinator

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    So having the subwoofer off the floor's surface will not necessarily make the sound better or worse? I was told by a good friend of mine that taking a rubber bicycle tire, filled with air, and placing it between the sub and the floor will increase the sub's output. I have not tried it yet but it sounded interesting.
     
  6. John S

    John S Producer

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    Hmmm, if you see it on the meter, then by all means do it.

    I often find things like this that people suggest, show nothing on the meter, sometimes I find they actually hurt output on the meter.

    Really hard to do just by ear.
     
  7. BrianWoerndle

    BrianWoerndle Supporting Actor

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    Generally you want the sub on the floor because the vibrations cause other things to rattle and color the sound. And you don't really want your rack vibrating. Especially if you have a DVD player sitting on the rack.
     
  8. Phil Iturralde

    Phil Iturralde Screenwriter

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    I concur w/JohnS suggestion and comments!!!


    Sounds like an old audio urban legend!!!

    Common sense would dictate if the Sub-woofer's were designed to deliver the best performance for the consumer with a rubber bicycle tire under them, ... the MFG would throw that in with the sub woofer's purchase to make sure you get the best designed performance.

    As of this time, ... I don't know of any sub MFG that includes a rubber bicycle tire with their sub's, ... let alone, disclose to the potential sub woofer reviewer that proprietary design requirement!

    Phil
     
  9. MikeNg

    MikeNg Second Unit

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    Well, I think the idea behind the bicycle tire is to isolate the sub cabinet from the floor - not much different in principle to the use of auralex pads. Well-braced/designed sub cabinets will keep their vibrations to a minimum. Play your sub at moderate levels and put your hand on it - do you feel a lot of vibration? You don't want that vibration transmitted to your rack. Bad for sound, bad for components.

    Having the sub directly touching the floor will probably not give you the best sound. Placement is key, so I think there needs to be some trial and error on your part to see where the best performance will be had.

    It may help to isolate the sub from the floor. A low-tech solution may be as simple as getting a scrap piece of carpet to lay underneath. If your sub already has rubber feet or spikes, then you may not even need this. Since you're getting a new rack, you might as well look for one that sits on spikes. This acts to prevent vibrations from being transmitted from the rack into the room. Most higher-end racks have this feature.

    My SPL meter cost me $50. Well worth it, and if you're lurking around these parts, yeah, you need to get one and move forward.

    My $0.02
    Mike
     
  10. BrianWoerndle

    BrianWoerndle Supporting Actor

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    Isolating the sub is crucial. You really don't want your rack vibrating, but the floor can also vibrate. If you are on a slab, you are in pretty good shape. But anything else, isolating the sub makes a hug difference. I have hardwood floors, and the Auralex Gramma pads made a huge difference with my subs. I now have 3 of them.
     
  11. DevinJC

    DevinJC Stunt Coordinator

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    Describe "huge difference" por favor.
     
  12. Mike_Gr

    Mike_Gr Stunt Coordinator

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    $40 bucks at radio shack (analog). Don't both with a digital meter. They work great and it will do everything it is supposed to.
     
  13. BrianWoerndle

    BrianWoerndle Supporting Actor

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    The difference was big enough that I thought I got a new sub. Everything in the room didn't rattle, the bass was clean, more defined, and more detailed. I know it is hard to describe the sound of a sub, but it was a very noticable difference.
     
  14. dany

    dany Supporting Actor

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    Hocky pucks work great if you think you need to put the sub on something. The #1 place is in the corner.
     

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