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Old 16th February 2019
  #5
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Positions and modes

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Originally Posted by RayGlz View Post
Thank you for your time akebrake!
My pleasure

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Yes! I tried to find a balance of the listener positions potentia problems.
As I’m a bassplayer myself I find this an interesting but seldom discussed question in Forums.

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A mapping of the nulls? Playing a sine wave at each freq and measuring spl every 2 feets like in a virtual mesh algong all the the walls and ceiling?
”Virtual mesh”! That’s a nice description!

A generic ”rule” when positioning speaker and listener in controlrooms is:
”Neither put speaker nor listener in a null by accident” (only by purpose).

The obvious next question is: Where are these nulls (below ≈150Hz) situated?
In a shoebox shaped room with rigid boundaries they are easily calculated.
Your room is ”close to” box shaped. A calculator like Hunecke will give a rough clue (and you also have REW WF & your average calc to compare with)

Sustained notes
The bass rig is fairly point source. Place it in a corner (to drive all modes efficiently)

Run Sines or Pink PN from REW generator (which ever you like best) and watch result on the RTA screen.
And then walk around in the room with the mic and a laptop(?) finding the null lines. Like "Isobars" with low pressure. Mark with tape on the floor.

These null-lines connects to room modes, which in turn connects to certain boundaries. ( Walls or Floor-Ceiling).

We now have low positioned sources (with good coupling to vertical modes) but also seated /standing listeners which affects how they percieve the vertical modes.

As Kick and the other drums are impulse-like signals first reflections will also play it's role.

Will your drummer prefer a rigid back wall (used to) or deep trapping behind his back?

/Ake