Subs Cancelling each other?

[TheJuggla1 10+ year member]

I heard subs can 'cancel out' each other. Lets use an example and say I got a pair of 15 12 10 and 8s, would there be any 'canceling' going on?

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[dave_damage 10+ year member]

tons, dont mix sub sizes.

 

[TnT_Sounds 10+ year member]

Try it and see.

 

[TheJuggla1 10+ year member]

tons, dont mix sub sizes.

Does the shape matter? Say I get a Square sub and mix it with a Circle Sub(Different amps of course) do they cancel as well?

 

[Davecubs14 10+ year member]

I wouldn't mix size, brands.....different sub amps...nothing...for it will cause some problems somewhere down the road.

 

[aho77 10+ year member]

for example i have 2 15s that sit side by side in a wall not up and down like thay sould be i have been told there is like 1 or 2 db differce with the subs side by side due to cancleation

 

[thevic24 5,000+ posts]

even using 2 subs facing the same way, there will be some sort of canselation. when they are facing each other there will be even more in most cases.

i would say just to try diffrent positions out and see which one sounds the best. you can even try reversing the phase on one sub and see how they sound while they are facing each other.

 

[thericanballer 10+ year member]

get two sony xplods. itll be the loudest system ever. but just dont mix sizes. or brands.

 

[thevic24 5,000+ posts]

get two sony xplods. itll be the loudest system ever. but just dont mix sizes. or brands.

not true...

one pup is all he would need but he is not yet ready for that....

//content.invisioncic.com/y282845/emoticons/crazy.gif.c13912c32de98515d3142759a824dae7.gif

 

[bhsdriller 10+ year member]

get a 15 for the lows and a 10 for the higher notes

 

[st8_of_mind]

for example i have 2 15s that sit side by side in a wall not up and down like thay sould be i have been told there is like 1 or 2 db differce with the subs side by side due to cancleation

when you have 2 subs side by side you actually can gain 3 dbs because of mutual coupling of the drivers. you would get more cancellation if the drivers were pointed straight across from each other without some type of a wall in between them. the wall would keep the sound wave from clashing into each other and canceling. think of it like tossing two rocks into a small pool, if you toss the rocks in on the same side close together you would get a larger ring of water movement than you would if you stood on 1 side and some one on the other side and you both tossed your rocks into the pool at the same time and the same distance from the edge. eventually the rings would come together and clash causing the wake to smooth out.

 

[PV Audio 5,000+ posts]

I heard subs can 'cancel out' each other. Lets use an example and say I got a pair of 15 12 10 and 8s, would there be any 'canceling' going on?

Yes they can, and it's a problem with what is called "phase". Different speakers have different response characteristics and consequently different phase delays. To make this simpler, let's use an example from mathematics: a sine and a cosine wave. All a cosine wave is, is a sine wave that is 90 degrees out of phase, or the other way, a sine wave is a cosine wave that is -90 degrees out of phase. To visualize this, look at the following plot:

In mathematics, pi/2 radians is equal to 90 degrees, so if you look at the plot of the sine wave from pi/2 on, you'll note that it's identical to the plot of the cosine wave starting at 0.

The reason this is relevant is because all that a speaker is doing is emitting sound waves, and as you can see from the plot, sine and cosine are just waves as well. Since there are two sides to a speaker cone, front and back, if you consider the wave coming off the front to be what's called "in phase", or has a phase of 0 degrees, then the wave on the back is completely "out of phase", or has an angle of 180 degrees. A wave that is 360 degrees out of phase is actually in phase as if you might know, 0, 360, 720, etc. are all called "coterminal" angles, or angles which end at the same point on the unit circle. Now, back to the speakers //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

If you take a 12" speaker and a 10" speaker and play them at the same time, they will have different phase responses due to the size of the cones and other various factors about them. While they might be playing the same frequency, that does not mean that their sound waves are in phase with one another. To think about this simply, imagine you start playing a 20hz tone on one 12" sub, and then start playing a 20hz tone on another 12" sub. Unless you start playing that second sub at the exact moment that the first one returns to its neutral position, the cones will not be in phase with one another, and you get interference which in this case, is likely to be destructive interference, which is where part of the waves cancel each other out. By adding speakers together, you want constructive interference which is making the amplitude of the output sound greater. That can only happen if the sound waves being emitted are in phase with one another. Note that there are a lot more factors to consider, such as enclosure type (ported enclosure make use of the back wave of the cone to make more output).

A useful application of phase is when doing show car installations where if you have multiple subwoofers, you'll mount some properly, and some inverted, as shown in the following:

That one subwoofer that is inverted is wired opposite to the others, aka, it has a negative signal wire going to the positive terminal, and the positive signal wire going to the negative terminal. Why? Because if it were wired normally, when the other speakers move OUT, it would also move OUT, which in this case, is moving in the opposite direction to the other subs. By wiring that one backwards, you can ensure that they are all moving in phase.

So to sum up, no, do not use different speakers in the same installation unless they are being used as a single system as in a 2 or 3 way loudspeaker. Otherwise, since different speakers have different phase responses, you can end up, with as you suspected, cancellation due to destructive interference as the sound waves are not adding, but are subtracting.

Hope that helps and wasn't too long winded //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

-Dave

 

[PV Audio 5,000+ posts]

when you have 2 subs side by side you actually can gain 3 dbs because of mutual coupling of the drivers. you would get more cancellation if the drivers were pointed straight across from each other without some type of a wall in between them. the wall would keep the sound wave from clashing into each other and canceling. think of it like tossing two rocks into a small pool, if you toss the rocks in on the same side close together you would get a larger ring of water movement than you would if you stood on 1 side and some one on the other side and you both tossed your rocks into the pool at the same time and the same distance from the edge. eventually the rings would come together and clash causing the wake to smooth out.

//content.invisioncic.com/y282845/emoticons/laugh.gif.48439b2acf2cfca21620f01e7f77d1e4.gif You just said what I did except in 1/16 of the space //content.invisioncic.com/y282845/emoticons/redface.gif.62fdbfe1a101588a808c4cff71bcb942.gif

 

[Varinabassing 10+ year member]

//content.invisioncic.com/y282845/emoticons/laugh.gif.48439b2acf2cfca21620f01e7f77d1e4.gif You just said what I did except in 1/16 of the space //content.invisioncic.com/y282845/emoticons/redface.gif.62fdbfe1a101588a808c4cff71bcb942.gif

But like the way you explained every aspect Thanks i learned alot today!!//content.invisioncic.com/y282845/emoticons/cool.gif.3bcaf8f141236c00f8044d07150e34f7.gif

 

[TheJuggla1 10+ year member]

Is there any way around this? Ex. I my squares only hit about 14-100Hrz Or something like that, can I get a circle sub that would only do only 100Hrz and up ?