Stacked or side-by-side they are not in the same location.

The output has now moved either vertically or horizontally. I would measure the difference and select the one that gives the best bass response. Vertical works well as long as they are not allowed to move, subs falling off of each other really puts the beat down on corners. This is commonly called "re-entry marks" so pay particular attention to that.

So let the measurements be your guide, congrats on more subs! If you are not sure, just build even more subs and make a quad group--you know you want to!

 

Stacked or side-by-side they are not in the same location.

The output has now moved either vertically or horizontally. I would measure the difference and select the one that gives the best bass response. Vertical works well as long as they are not allowed to move, subs falling off of each other really puts the beat down on corners. This is commonly called "re-entry marks" so pay particular attention to that.

So let the measurements be your guide, congrats on more subs! If you are not sure, just build even more subs and make a quad group--you know you want to!

While more subs is not feasible at the moment I can't say it is a bad idea. However, I believe the for subs lf they are within a quarter wavelength they can be considered co-located. At 80hz that is about a 14' total wavelength so a quarter of that is 42" Now I can't say why I believe that or even if it is true and I can't find any confirmation of it either. I have seen others say the same thing though. Now remember that this is for maximum coupling of the drivers not necessarily the best response.

 

I had planned to stack them on their side hook them up together for a 4 ohm load

I can't answer your question about co-locating subs, but I have a question about this statement. How could you wire 2 dual 2ohm speakers together to get 4ohms?

I thought you could only wire them like this: Subwoofer Wiring Diagrams for Two 2 Ohm Dual Voice Coil Speakers (i.e. .5ohm, 2ohm, or 8ohm).

 

I can't answer your question about co-locating subs, but I have a question about this statement. How could you wire 2 dual 2ohm speakers together to get 4ohms?

I thought you could only wire them like this: Subwoofer Wiring Diagrams for Two 2 Ohm Dual Voice Coil Speakers (i.e. .5ohm, 2ohm, or 8ohm).

Each box has 2 subs with dual 2 ohm voice coils. Hooking those in series gives you an 8 ohm load per box. Hooking the 2 boxes up on parallel will then give you a 4 ohm total load. Basic series-parallel circuit just spread out.

 

Hi,

The closer the subs are to the dimensions of the room, the more similar their response will be and so you end up with something more similar to the idea of co-location. The more variable distance the subs are from the boundaries of the room, the more differences you will see in their response and you may need more time management (delay) to get a summation from them as a group unit.

Which is better will be based on your room's dimensions, your listening position(s) and the relationship of your subs as a unit assuming you achieve summation with them from time management. You will mainly see the differences and what's best for you via measurements. I would say try both arrangements and see what your measurements tell you for your room. One setup may have more SPL in a particular range. And one setup may just have a flatter even response across more seats.

Very best,

 

Four 18s. Sounds like the right amount of equipment to experiment with placement.

 

I'm going to be close to 1/2 placement on 3 sides. Side 4 is full of other stuff so no sub going there which mean one of the other 3 will have 2 or possibly 3 subs. Right now the back wall has a Devastator, the front has a McCauley 18 and the right side a dual 15/12. If I don't get a new screen the new boxes pretty much have to go on the back wall with the Devastator.

 

Place then where ever. Run rew using a mic and figure out what measures the best without dips.

Nobody can really tell you where they are to be placed as this is room specific conditions.

Up front may work. Or somewhere else.

Best of luck!

 

If they are less than 1/4 wl apart at the upper xover point they are effectively co-located.
Driver location, laterally or vertically may have some effect on amelioration of some room modes depending upon their position.