Subwoofers - crazy upgrade!

@gdaddy1 

sorry, but it's not. At the same sound level in the room, the 4 subs/amps put out the same energy whether they are stacked one on top of the other or spread out. When stacked, acoustically both subs behave as one larger one, but still outputting the same energy as if they were spread out. The advantage of spreading out is the more even bass response in the room across different locations.

Stacked subs provide larger headroom, but that's rarely the issue with multiple good subs in a living/audio room. Stacked subs can push twice the power and surface, but that's headroom and not SPL at a given sound level in the room.

@lewinskih01  At the same sound level in the room, the 4 subs/amps put out the same energy whether they are stacked one on top of the other or spread out. 

That's just not true..it takes LESS energy to get the same sound level in the room. When you stack them, without changing any of the settings, you would get a 3db to 4db boost in your room just by making stacks of two instead of 4 seperated locations.

Acoustic coupling vs. amplifier power

People often confuse these.

Case 1

One sub.

100 watts.

Reference SPL.

---

Case 2

One sub.

200 watts.

Cone excursion increases by about √2.

Pressure increases by √2.

Result:

+3 dB

---

Case 3

Two identical subs.

100 watts each.

Total amplifier power = 200 watts.

Pressure doubles because both cones radiate together.

Result:

+6 dB

 

@ozzy I have 4 subs, placed in the corners of the room. But I wonder if stacking 2 in the front would be better?

In 2011 when I slightly asymmetrically corner positioned two Velodyne 12" Plus, one DD-18" and a 15" Earthquake Nova in a large vaulted living / dinning room.This eliminated ALL that rooms standing wave bass modes. The Velodyne Auto EQ and gain were changed substantially. This distributed bass array became my audible low frequency reference experience even today.

In 1967 a recording engineer sold his Octavium Subwoofer cabinet to me and demonstrated how to find any rooms bass modes for optimal sub positioning, now referred to as the subwoofer crawl. While the distributed bass array essentially eliminates the need for the crawl, it's still nice to know a rooms modes. 

Other than a brief time with a huge REL Studio III "Sub-Bass System" using its corner placement instructions I have found corner or front wall positions to be very problematic for -3dB rated subwoofers. The -6dB Studio III simply didn't play low enough to excite the rooms standing waves, as a result it could be located most anywhere in the room.  All the best.

@gdaddy1 

I believe you are confusing how the physics at play work.

For a given in-room SPL, using a given cone driver, a 200W amp won't sound louder than a 100W unless the former is asked to play above 100W. A 200W amp provides more headroom - that's it.

Anyway, I'm not interested in debating what seems to me like a moot point. I just wanted to make sure newcomers didn't take away a magical solution that won't pan out. Anybody with an SPL meter can validate this for oneself.

@lewinskih01  I just wanted to make sure newcomers didn't take away a magical solution that won't pan out.

Discourage experimentation using proven physics. 

So, you want to protect newcomers from trying some magical, make believe, solution that doesn't work? It's clear that you have never tried coupling subs. REL,PS Audio, SVS  all recommend stacking. It's really not a question of whether it works. They already know it does.

I'd bet that of your four subs there are one or two that are weaker in output than the others. They get set at higher levels due  to their position in the room. If you stacked them in pairs of two, the dynamic range would improve greatly and REDUCE the gain settings and reduce distortion.

Yes, a simple SPL meter does validate that it does work. Try it, youll be surprized.

Using LESS power to produce the same acoustic level is the trick you fail to see.