# Effect contra inpedance

Discussion in 'Amps and Cabs [BG]' started by semborg, Mar 19, 2005.

1. ### semborg

If you are going to use a cabinet with two loudspeaker with the impedance of 4 ohm (250watt 2x10) paralell with a cabinet with one loudspeaker with the impedance of 4 ohm (250watt 1x10) with an amplifier giving 250 watt RMS in 4 ohms and 500 watt RMS in 2 ohm.
Are the two cabinets going to share the total effect equal (250watt each)?

Will the two cabinets give same volume dB?

2. ### PassinwindI Know NothingSupporting MemberCommercial User

Dec 3, 2003
Columbia River Gorge, WA.
Owner/Designer &Toaster Tech Passinwind Electronics
Yes.

Will the two cabinets give same volume dB?

That depends on the sensitivity of the two cabinets, not their power rating.

3. ### semborg

It is exacly the same loudspeakers in the cabinets. But 2x10 in one and 1x10 in the other. Will all three speakers have same volume? or will the single 1x10 have a higher volume?

Because the 1x10 gets 250 watts from the amp and
the 2x10 gets 250 watts from the amp
So the 1x10 has more power

Am I right?

4. ### PassinwindI Know NothingSupporting MemberCommercial User

Dec 3, 2003
Columbia River Gorge, WA.
Owner/Designer &Toaster Tech Passinwind Electronics
First off, they can't be exactly the same drivers, or the cabs would have different impedances from each other.

It's not straightforward as you'd maybe expect. The coupling effect of the two drivers in the 2 X 10 being in close proximity comes into play. If one cab's on the floor, and one is on a stand on the other side of the stage near a corner, that potentially changes the answer a bit as well. The sensitivity boost that a 2 driver cab benefits from could very well give you equal apparent volume from both cabs. If you have the cabs already, just try it and see what you get.

5. ### semborg

I dont understand what you are meaning. Do you answer my question?

It is same model cabinet, The only difference is that one has 2x10 and the other 1x10. It is all the same except that.

So 250 watt will go to one cab, and 250 watt to the other cab.

250 watt to 1x10
250 watt to 2x10

So in the 2x10 tab, the 2 speakers has to share 250 watt.
But in the 1x10 1 speaker got 250watt.

Will this one speaker in the 1x10 cab "work" more than the other's?

Or do you mean that the 1x10 is not same as the 10 speakers in the 2x10?
so the 1x10 speaker can handle more power than one speaker in the 2x10?

Thank you alot for helping me!

6. ### Mudbass

What Passinwind is saying is no, a 1x10 and a 2x10 will not be equal in volume because of the proximity effect of the speakers in the 2x10 cab. When you mount two identical speakers on the same baffle next to each other and feed them the exact same audio signal, the two speakers couple together sonically and behave just as though they were one speaker twice the size. The effect also causes a +3db boost in volume. A single speaker mounted in a cab gets no +3db boost because there is no coupling effect and won't be as loud as the 2x10 cab.

7. ### semborg

Ahh, now I am getting it!

Thank you alot!

8. ### PassinwindI Know NothingSupporting MemberCommercial User

Dec 3, 2003
Columbia River Gorge, WA.
Owner/Designer &Toaster Tech Passinwind Electronics
Mudbass explained my main point perfectly, thanks! I should have said "equal or greater volume", actually.

Will this one speaker in the 1x10 cab "work" more than the other's?

Yes, it'll see double the power either one of the other ones do.

Or do you mean that the 1x10 is not same as the 10 speakers in the 2x10?

Yes. The 1 X 10 driver is 4 ohms, the ones in the 2 X 10 are probably 8 ohms each. Are they equal in sensitivity? I don't know.

so the 1x10 speaker can handle more power than one speaker in the 2x10?

No idea, but you can figure that out from the respective power ratings of the cabs. That'd be a good thing to know, BTW.

Thank you a lot for helping me!

I live to serve and confuse!

9. ### semborg

Thank you again.

But do you think it will end up good adding 1x10 to my 2x10 cab?
The amp will go 500 watt at 2ohm instead of 250 watt at 4ohm.

10. ### PassinwindI Know NothingSupporting MemberCommercial User

Dec 3, 2003
Columbia River Gorge, WA.
Owner/Designer &Toaster Tech Passinwind Electronics

If you want max volume, I'd get a 2 X10, but if you think you'd use just the 1 X10 for smaller gigs, it might be cool to have one of those.

11. ### semborg

Yeah, it was that I thought of. Easy to have the 1x10 alone on small gigs, very easy.

But there must be more power with 2x10 + 1x10 than just 2x10.
The amp goes 500watt instead of 250watt.