Coupling "unmatched" speakers?

[gadgetx23]

I've read on here before that it's a bad idea to couple different size/make of speakers together. Could someone explain to me what sort of problems I would expect to run into if I were to try coupling my current pair of 15" subs with another pair of 18" subs? Is this situation just not preferred, or is it an absolute no-no?

[prosigna]

It is not an absolute no-no. I term absolute no-no to be something that is damaging or a safety hazard.

 

You may not like what you get. You may find it to be pleasing.

 

I have used 18" front loaded subs with 15" horn (w-bin) loaded subs to good success. Front loaded subs tend to be clearer and horn loaded tend to have more thump. Mixing them can give you a best of both worlds.

 

Sub frequencies respond to coupling "differently" than mid-range and hi frequencies. I won't even try to explain that one without being able to use drawings. I will let someone else try.

[Audioaxe]

This is achievable but you need to watch your impedence, if you end up with an overall ohmage of between 2 and 16 ohms, taking into consideration that your amp can run below 4 ohms and has enough power to handle it then it shouldnt be a problem, this kind of coupling will need to be monitored and will more than likely need more attention from the Eq's.

[gadgetx23]

Thanks guys! As you may have noticed from my other post, I'm trying to put together a larger system for outdoor shows this summer. One of the options I was tossing around for subs was to buy 2 18's, and for a little extra boost still include my 2 15's; just didn't know if the problems would outweigh the benefits.

 

If I were to try it, what would be the best arrangement?

 

1: 15 and 18 per side

2: 15's on outsides, 18's in center

3: 18's on outsides, 15's in center

4: All in center

[Audioaxe]

If you usually run 2 stacks then just distibute it evenly, i dont know the boxes you are using or their size but i would put the 18's on the bottom 15's on top then high/mids if you dont have this luxury then i would put the high/mids on top of the 15's and put the 18's on the inside of the stacks, you can put them anywhere between the two stacks but just try to keep the drivers as physically phase aligned as you can (try to keep the rear of the drivers in a line, not the boxes)

[Craig Vecchione]

 

Thanks guys! As you may have noticed from my other post, I'm trying to put together a larger system for outdoor shows this summer. One of the options I was tossing around for subs was to buy 2 18's, and for a little extra boost still include my 2 15's; just didn't know if the problems would outweigh the benefits. If I were to try it, what would be the best arrangement? 1: 15 and 18 per side 2: 15's on outsides, 18's in center 3: 18's on outsides, 15's in center 4: All in center

 

 

Any arrangement that keeps the different speakers away from each other is fine, so 2 and 3 would work.

[gadgetx23]

 

The issue is that if different speakers are reproducing the same frequencies, because they can respond differently, some bands of frequency may be reinforced, and others cancelled, resulting in odd, notchy sound. The only way to know whether two speakers will cause a problem is to try them. In some cases it's a disaster, in others a pleasant surprise. Any arrangement that keeps the different speakers away from each other is fine, so 2 and 3 would work.

 

 

Thank you very much - that's exactly what I was looking for!

[Dan Magers]

 

Thank you very much - that's exactly what I was looking for!

 

 

Try one 18 and one 15 box close together outdoors. Disconnect the 15. If the bottom end gets louder with just the 18 then try a different placement. Perhaps 15s on one side 18s on the other.

 

If they couple well and is louder with the 15/18 then you will get max out out of your system with a center clustered of 18/15/15/18.

 

More on subwoofer cancellation :

 

http://www.prosoundweb.com/live/articles/jbrusi/pa.php

[gadgetx23]

Thanks Dan; that's also good advice. I actually found that power alley article on PSW awhile back when I first noticed a "combing" effect in a live situation. Thereafter I have always moved the subs to the center whenever possible.

 

It sounds like this will really come down to trying it out in a live situation to see what works and what doesn't. I just wanted some theory/knowledge from experience to go off of before I try it.

 

I've seen diagrams of how the waves cancel and boost each other with a single source (center) and from 2 sources (each side). I even recall seeing a little program where you could move the speakers around the room to see how it changes. I've never seen what happens from 3 sources though? (each side + center)

[Craig Vecchione]

It's important to note what Dan wrote...to experiment outdoors. The room will interact in similar ways, so you need to minimize that variable as much as possible.

[Audioaxe]

You might also find that it will change from room to room, so something you like in one room wont necessarily be good for another.