Single Bass Array from in wall 3-way speaker

Hey people!

As I do some changes in my listening room I try to perform some measurements - probably interesting for someone.
This is a listening room for mixing/mastering after non environment principle which also works as my measurement room with some additional mobile absorbers. For my test listenings with KH120ii I changed the usual layout and added additional absorption.

My main speakers have their low frequency drivers close to the points where they need to be for a single bass array. And I wanted to show you that this works and is a fairly easy way to have better low frequency performance.
Here is the setup:

Measurement setup - pic.jpg


I did 6 different microphone positions but all on about the same plane 10-20cm after the little table, varying up/down and left/right position (the directions a BSA should work). Cause of the not perfect positioned LF drivers I expect them to work as array till 70-80Hz.

Here is the variation from the KH120ii lf driver at mic positions:
KH 6 pos.PNG

That's actually not bad - my room is extremely well dampened. Measurement is a sweep of 2s, no windowing at all. But at 100Hz it's about +-8dB and at 70Hz +-4dB. No room measurement system of the world can do anything against that.

And that's the array:
REF 6 pos.png

I got a lot more low frequency content - that's the glory of closed speakers tuned to the room. At 70Hz I have about +-1,5dB and at 100Hz (where the array is not working any more) I'm still better with +-6dB (but most curves are pretty close, only 2 extreme mic positions are far from them).

For a more scientific view I would have to compensate the distance of the mic and absolute level and take better care about these microphone positions - but I hope it's clear that it has a positive effect and with thoughtfull positioning of your lf drivers you can chancel a few room resonances - for "free".

(p.s.: this only works when the music/film content is mono at low frequencies! Which it mostly is)
 
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4 drivers are ok for this wall, it's about 330x250cm (not easy to tell with that deep absorbers, they change the resonance frequencies). But the position is not perfect, so you loose a little.
It still works great up to 50Hz and good up to 80-90Hz. I measured 1-2 pretty wild microphone positions here which are far from a listeners seat to check the principle.

Distribute your low frequency drivers nearly always helps to some degree - do it when you can do.
 
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