Dual Opposed Woofer for low Mms have benefit?

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#21
Really Dave?
Isn't Roy F. Allison's works all about boundary and how to use them for low end reinforcement? I know it's a bit pushing the definition's boundary ( 🙂 )but it includes a wise choice of xover freq to mitigate SBIR in the annoying range while still getting the interesting effect.
In my view/understanding it's interrelated, the same effect at play.

And you will still have modal issues related to driver location/room dimension ( just try the simulator i linked to see) so... i find the (freq) range at play more a grey area rather than full white or black.
 
#23
first time i read about SBIR in this thread, never knew it existed before. when i read some articles explaining how to reduce it, all related to reflection and room mode. i solved it using 2 subwoofers on L/R side, while dual-opposed should be intended to reduce cabinet vibration. cmiiw
 
#24
TNT said:
Se Audio-Pro Ace-Bass.
Click to expand...
That takes me way back.
I clearly remember a review & test results in Australian HiFi that showed amazing low bass extension being achieved with quite a moderate size enclosure.
However, the enclosure size really does come down to the TS parameters of the drivers,
and from memory, the model I refer to was actually an Active design > so who knows what EQ was incorporated and what the 'max SPL' was.
 
#26
Audio>X said:
That takes me way back.
I clearly remember a review & test results in Australian HiFi that showed amazing low bass extension being achieved with quite a moderate size enclosure.
However, the enclosure size really does come down to the TS parameters of the drivers,
and from memory, the model I refer to was actually an Active design > so who knows what EQ was incorporated and what the 'max SPL' was.
Click to expand...
I'm no expert like Dave, but for me some principle that i understand that i will not follow AR9 style

  • 12" woofer which reach below 30Hz should be on separate box
  • 8" to 1.5" transition gap is huge

I bought Dyn BM15 just to get extra pair 24W100, i listen to this big studio monitor and i dont like it when 8" has to play above 1.5kHz.

my previous plan to make 3 way like Avalon PM 3.2, Esotar430 have been used as low as 250Hz in car but i think extra 6" to fill 200-800Hz will be beneficial at high volume later on my 5x6m room.

so 4 Way + DOS is ideal one for me
 

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#28
gadut said:
I have built 2 sealed dual opposed subwoofer 2x12" with Kappa 12VQ which has 180gr Mms & 16mm Xmax. now i'm going to built 4Way floorstander which will include 2 of Dynaudio 24W100 in sealed 43L, Fb around 65Hz and lpf maybe around 160Hz. built with 8ch dsp & cabinet shape inspired by Avalon.

I'm contemplating between should i go with dual-opposed woofer (front-back or side by side) for cancelation benefit or both woofer on front baffle like regular multiway. considering it's low Mms, not so deep bass, and only 8mm Xmax acceleration might not have too much force. also will it be still good for rear facing woofer up to 160Hz?

Thanks
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Since the woofers are mounted at an angle, and not on the same horizontal plane, the benefit you're aiming for is already reduced.

This is because the woofers won't experience the same force when moving in a given direction.

In general, mounting drivers that handle significant excursion (low-end) at an angle (or worse, facing upward or downward) is less than ideal.

It introduces an offset in the suspension, which increases distortion en non-lineairities in both Kms(x), BL(x), and even Le(x).

You can find more on this in several articles on Klippel’s website.
 
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