If you can't have your speakers more than about 1.5m away from the front wall then it is sometimes recommended to put the speakers as close as possible to the front wall instead.
With speakers > 1.5m from the wall the first cancellation dip due to SBIR will be at about 57Hz (below the typical 80Hz crossover - allowing the sub to fill in the dip).
For speakers that are 35cm deep, varying the gap between the wall and speaker, the first cancellation dip goes as follows... (I think - please check math)!
Having the speaker as close as possible to the wall pushes the SBIR dip to higher frequencies, making it easier to absorb the back wave.
The cancellation frequency is pushed quite a lot lower just by moving the speaker out far enough to put a panel behind. (This is in a frequency range where the efficiency of absorbtion changes quite rapidly with frequency).
Some also suggest that an air gap behind the acoustic panel can also improve absorption efficiency.
So how about this concept...
The speaker is right against the wall. The acoustic panel has a hole the same size as the speaker. (It is mounted sort of like a collar or almost approaching an in-wall type mounting). (Could also be achieved with two panels - one either side of the speaker).
Top view sketch...
Do you think the panel will still be able to do a good job of absorbing the back wave (after reflection from the front wall)?
There is a trade off between having the speaker as close as possible to the wall, and having enough room to physically install a panel. Where do you think the balance lies?
Anyone tried this, or something similar?
With speakers > 1.5m from the wall the first cancellation dip due to SBIR will be at about 57Hz (below the typical 80Hz crossover - allowing the sub to fill in the dip).
For speakers that are 35cm deep, varying the gap between the wall and speaker, the first cancellation dip goes as follows... (I think - please check math)!
Baffle to front wall | First cancellation dip |
35cm | 243Hz |
40cm | 213Hz |
45cm | 189Hz |
50cm | 170Hz |
55cm | 155Hz |
60cm | 142Hz |
65cm | 131Hz |
Having the speaker as close as possible to the wall pushes the SBIR dip to higher frequencies, making it easier to absorb the back wave.
The cancellation frequency is pushed quite a lot lower just by moving the speaker out far enough to put a panel behind. (This is in a frequency range where the efficiency of absorbtion changes quite rapidly with frequency).
Some also suggest that an air gap behind the acoustic panel can also improve absorption efficiency.
So how about this concept...
The speaker is right against the wall. The acoustic panel has a hole the same size as the speaker. (It is mounted sort of like a collar or almost approaching an in-wall type mounting). (Could also be achieved with two panels - one either side of the speaker).
Top view sketch...
Do you think the panel will still be able to do a good job of absorbing the back wave (after reflection from the front wall)?
There is a trade off between having the speaker as close as possible to the wall, and having enough room to physically install a panel. Where do you think the balance lies?
Anyone tried this, or something similar?
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