Multiple Speaker Impedance Power Dispersion

[Trevor Findley]

Hello. I understand that by mixing an 8 ohm 115 cab with an 8 ohm 210 cab that the total imedance would be 4 ohms. Does this mean that since the 10" speakers would each be 16 ohms that they would each individually get half as much power as the 15" is getting? Thanks.

 

[B-string]

Individually the 10's get 1/4, combined they get 1/2.

 

[two fingers]

What B said.

And all of those numbers are rounded. Speakers are simple resistors. They don't have finite resistance (impedance ) values. So it will bounce around a little based on everything from frequency to wattage input to any number of things.

But for now 8 and 4 are clean figures and will suffice.

 

[Trevor Findley]

Thanks for your responses. You mean the individual 10's get 1/4 of the total power, right? What's stopping the 15 from overpowering the 10's? Is it constructive interference?

 

[B-string]

Overpower? How, in what way overpower? Speakers convert electrical energy into sound (and waste heat).

 

[RoadRanger]

To get an 8 ohm 2x10, each driver would need to be 16 ohms if in parallel. If in series they would need to be 4 ohms each. In either case yes, they each get 1/4 the total amp power with the single 15 getting the other half.

 

[Arjank]

Speakers convert electrical energy into sound (and waste heat).

+1

Actually it would be more (technically) correct to write "Speakers convert electrical energy into heat(waste) and only a small portion into sound"

 

[StraightSix]

What's stopping the 15 from overpowering the 10's? Is it constructive interference?

The real problem lies in the fact that the two tens are sharing half the output power between them and the fifteen is having to cope with half the output power on its own.

There is always the danger that the fifteen could be damaged by too much power but this is normally only really a problem with a 115/410 setup where the single fifteen is trying to cope with the same amount of power as four tens.

Imagine a 115/410 setup (each 8 ohm) with a 500W @ 4 ohms amp - the four tens are getting roughly 62.5 watts maximum each whereas the fifteen is having to potentially cope with up to 250 watts output on its own...change the amp for an 800W model and the poor old fifteen has to cope with a potential maximum of 400W on its own while the four tens will get around 100W each maximum.