Tweakers' Asylum

RE: New room, new problems, long

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Paul_A

A

In Reply to: RE: New room, new problems, long posted by johnsonad on February 03, 2010 at 21:10:55

Since the bass is generally too loud--when you are standing, or out of the room--it seems like you should try to correct for that first. Moving the speakers away from the wall would help because the closer a speaker is to a wall, the more it reinforces the bass. Generally, speakers work better away from the back wall because they will image better and the bass will not be boomy. If you move the speakers away from the wall, you may find that the geometry of the nodes changes so that you don't get cancellation at your sitting position. It's worth a try anyway.

Follow Ups:

RE: New room, new problems, long - David Aiken 13:20:17 02/04/10 (2)
There are 2 causes of "cancellation". One isn't really so much a cancellation. The high and low pressure zones that occur with a room mode are fixed in location and moving the speakers won't change them in the slightest. There is also a cancellation that occurs for the frequency whose wavelength is 4 times the distance of the speakers from the wall behind them. The frequency of this wavelength will change as you change the distance between speaker and wall but you can't avoid the cancellation by doing so. All you can do is change it's frequency. That can be used to advantage at times by moving the speaker until the frequency at which this cancellation occurs coincides with the frequency of a troublesome room mode peak so that you use the cancellation related to speaker distance from the wall to weaken a peak related to one of the room dimensions.

The problem with moving the speakers to weaken bass in this case is that the room is small and that means that there's less flexibility in how much distance you can place the speakers from the walls. In many cases you can't move them far enough from the wall in order to weaken the bass support they get from the walls sufficiently to solve a problem without ending up with them so far from the wall that their position is simply unworkable in the room.

David Aiken
- Perhaps - Paul_A 14:09:01 02/04/10 (1)
  What you say sounds correct. The room nodes obviously don't change, but as you said, you can use the speaker position to cancel nodes. Even if at the fundamental frequency, the speaker would have to be moved too far into the room to be practical, a smaller distance would probably cause cancellation of some overtones, and because the room is being energized differently, other wave interactions might turn out to be helpful. It's easy enough to try out. It sounds like the bass is generally too loud, so I think moving the speakers away from the walls, say about 12" is still a good idea. Since an equiiateral triangle is considered a good speaker-listener configuration, moving the chair towards the speaker along with moving the speakers out from the walls might do the trick. Moving the speakers forward would cut cown the boom, moving the chair would get it away from a cancellation zone.
  
  Of course it would be a good idea to have bass traps and also wall absorbers placed in locations arrived at through trial and error because absorbing bass will prevent it from cancelling itself out, so any room node cancelation should be reduced.
  - RE: Perhaps - David Aiken 23:53:10 02/04/10 (0)
    I didn't get the feeling that the bass was too loud. What was said was "When sitting in the listening chair it significantly decreases but once I stand it is present and boomy seeming to fill the room. The bass is equally loud when I walk into the kitchen or side bedroom which open into the living room."
    
    So the bass is low in level in the listening chair, louder and boomy when standing or in some adjacent rooms. Uneven bass response, and too low when seated which is probably the normal listening position.
    
    As for moving the speakers 12" away from the wall, mine are a fraction less than 2 metres from the wall behind them and 1.3 metres from the side walls, measured to the centre of the front baffle. I don't think 12" is far away and I know it's way too close for the speakers I have.
    
    David Aiken

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