Bass management -- the trick of putting absorbers at a front null

Thanks, Rego. I will message you if I am buried under traps! When you say, "The idea is that a frictional absorber necessarily is placed away from a wall ... not always very practical."

I know that frictional absorbers are placed away from walls -- to gain the extra absorption from a distance to the wall roughly equal to the width of the traps, if I remember right. 

But Grimani is suggesting something different than this. He is suggesting placing them very very far from the wall in order to capitalize on a null endemic to the room's modes. That is an application utilizing a different phenomenon, no?

By the way, in terms of having multiple subs, I'm thinking less of this as a solution as I've played around with the Room EQ Wizard's room simulator.

Try it out, but it basically lets you set up a rectangular room with speakers and a sub so you can try out different placements.  Based on those simulations, I'm not sure if multiple subs really does all that. I'm not claiming expertise, I'm just saying that the evening out effect is not as good as I thought.

Thanks, Erik. I'll take a look, but the problem is that my room's irregular shape and non-hermetic situation makes it impossible to put into these room simulators. I use REW a lot but it's as much a systematic try-and-see and try-and-listen approach.

Again the idea for placement as in the video diagram at a null position uses the idea of equalization of relative high to low pressure areas with a velocity.

That is an application utilizing a different phenomenon, no?

Yes-but a same phenomenon as any frictional absorber with the variables being frequency and absorption band.
My emphasis would be to acknowledge the 3D environment being helpful with placement.
The example (diagram presented in video) uses 50 Hz as the frequency range and appears to position the panel perpendicular to the wall and parallel to the end wall (assuming a rectangular plan) illustrating the idea that can work to ’level’ an imbalance at a narrow frequency range.
A narrow band (mid-high frequency absorption) frictional panel could be placed parallel to a side wall, perpendicular, and any angle from 0 deg to 180 deg.

How can it be from 0 to 180 degrees if it needs to intersect with null in the room from one wall to the other.. If it is only so wide (the null) and using the width of single panels, what goes by the panels (untreated) will literally come back and bite you in the As$. I see how it works, and in a LONG room it may be practical, IF you can get the break closer to a front or back wall.. BUT in my listening room?

Pretty darn UGLY having a break dead center of the room. To treat a (50hz) problem wave. What about 80 and 120. LOL It would start looking like huge chess board Wouldn’t you agree..

The spring traps address 3 different areas and just needs to be adjusted for volume and the frequencies you want.. I like that kind of thinking...

Honey I fixed the bass problem..

Click Click, I’m peaceful she’s not.. :-) The spring traps I could get away with in the front room but 1.5 meter hurdles, that’s a bit of a stretch. Get Ready, Set, GO!!!!