A theoretical question regarding bass isolation in an apartment

[Chrispy]

Interesting, curious how it works out in the end.

 

[Sokel]

Here's a real word example:

Is it acceptable to run a subwoofer/subwoofers in an apartment building?

Nah. This is a subwoofer! Apparently that's an actual consumer item for home theater. (Abandoning the sympathetic half of my brain...) WTF is wrong with people? Who on gawd's earth needs that? Reminds me of those absurd "boom car" battles or food eating contests or any other...

www.audiosciencereview.com

Note that my house is double reinforced steel construction (we didn't want columns in it) so basically a box.
Now,I measure at least two or three thick concrete walls plus the distance plus that my listening room is fairly shielded and treated (but not for as low as subs)

And it was still audible at this extreme test,not like sound audible though,more like rumble or earthquake audible.

I'm afraid that you will have to take extreme measures if you like it to be inaudible down to 20Hz.

 

[krabapple]

First, don't do this, place the sub 12 to 18 inches away from the wall. You risk 'bloating' if you place it directly against the wall.

Do you mean 12-18 between wall and the rear of the sub? Because most substantial subs already put the center of the driver cone 12-18 from the subwoofer back panel.

 

[autoteleology]

Do you mean 12-18 between wall and the rear of the sub? Because most substantial subs already put the center of the driver cone 12-18 from the subwoofer back panel.

From my perspective, if you can control the modes that result from being against a wall with EQ, wouldn't having rhe subwoofer cone directly against the wall be better, since it aligns the reflection off the wall closely with the phase from the primary signal for that reflection? Even more so if you put a subwoofers in each corner? Or are the wavelengths so long that it doesn't really matter? I don't know a whole lot about phase alignment with reflections, so genuine question.

 

[NTK]

From my perspective, if you can control the modes that result from being against a wall with EQ, wouldn't having rhe subwoofer cone directly against the wall be better, since it aligns the reflection off the wall closely with the phase from the primary signal for that reflection? Even more so if you put a subwoofers in each corner? Or are the wavelengths so long that it doesn't really matter? I don't know a whole lot about phase alignment with reflections, so genuine question.

For rectangular rooms, below are the results of the simulations in the "multi-sub" paper by Harman's (at the time the paper was written) Todd Welti and Allan Devantier. MSV is mean spatial variance -- the variance of the bass (20 - 80 Hz) in a 2 m × 2 m seating area centered at ~1/3 room length from the rear wall. The "best" (using the chosen metric of MSV) configurations are 4 identical subs with one sub at mid-point of each wall (config 6), followed by one sub at each corner (config 5).

 

[Philbo King]

I am in the process of designing my home theatre / studio to isolate my subwoofer from my next door neighbor in my apartment, with whom I share a single wall with on one side of my room.

The thought exercise I am considering that my entire room layout hinges upon is as follows:



The plan is to use heavy industrial steel racking that spans the width and height of my apartment wall, filled from floor to ceiling one foot deep with brick, and then sealed on both sides with several hundred pounds worth of metal sheeting, with one or two layers of acoustic blankets hung from the ceiling, then placing my subwoofer against this wall and hoping that the bass reflects outwards and upwards back towards the listening position and not through the wall.

If the wall does a good enough job of reflecting sound, this should, theoretically, be a better system than having the subwoofer on the other side of the room (thirty feet away), due to the fact that the wall, being closer, should block an essentially infinite "field of view" before reflecting off the room, rather than a limited field of view of whatever the base of an imaginary pyramid leading from the subwoofer to the wall would cover in area, plus the attenuation from the inverse square law due to the distance.

Thoughts?

You might consider whether the floor will support a thousand pounds of bricks in the span of a foot or two. If it falls into the next floor down you'll likely lose your damage deposit...

 

[Karmacoma]

It reminds me of a studio designed in the beginning of the 80's which has perfect bass isolation. It only took 3 whole meters of isolation on the walls/ceiling... they used to do things right back then.

 

[DMill]

Seems like moving would be less work

 

[kemmler3D]

For rectangular rooms, below are the results of the simulations in the "multi-sub" paper by Harman's (at the time the paper was written) Todd Welti and Allan Devantier. MSV is mean spatial variance -- the variance of the bass (20 - 80 Hz) in a 2 m × 2 m seating area centered at ~1/3 room length from the rear wall. The "best" (using the chosen metric of MSV) configurations are 4 identical subs with one sub at mid-point of each wall (config 6), followed by one sub at each corner (config 5).

View attachment 393153

This is actually a really informative chart, at first I glance assumed it was just a map of the SPL around a square room, but it's actually a chart of how bad each configuration is for each size of room... let me see here, my room is... somewhere in the 30+dB zone. Moving the subs to the middle of the wall would apparently help a lot, but not with my marriage.