ok heres the situation say i have a subwoofer that is 4 ohms from the factory and that impedance doesnt work for me and i want to change the ohms on just that one woofer by adding say a resistor with the correct specs i guess it would be called a resistor to make the amp see say 8 ohms with it hooked up inline would this work and fool the amp? i kinda want to know if this works for flexability and testing.

 

Anybody know? I was wondering if you could do this too.

 

You could use an inline resistor....
BUT, it's going to need to be a relatively large resistor, or a bunch of small resistors. You'll basically need a 4ohm 200w resistor (depending on what you're running, could be more, could be less.) But a power rating like that doesn't come easy, or cheap. Your other option is to make a very large resistor with a high wattage rating by taking multiple smaller wattage rating resistors, and creating a gang box full of them.

/---R---R---R---R-\
-------R---R---R---R--------
\---R---R---R---R--/
\---R---R---R---R/

--- = Wire
R = Reisistor (in this case 4ohm 5w resistors)
In this case, you'd have built a 4ohm, 80w resistor.


Your best bet... buy another of the same sub. You'll get twice the cone area, and the ability to wire them in different configurations for different loads.

 

Why doesn't the impedence work for you. Be more specific.
Perhaps I can help out.
This is Mike's dad; I am an electrical engineer by profession.

You will find that using a resistor will be problematic.
You said it yourself - you need impedence, not resistance.
Try this - put an ohmmeter on the speaker terminals. Do you read 4 ohms ( or whatever it is rated ) ??
No you don't. You will read 0 ohms, or close to it.
That is because the voice coil of the speaker is just a long wire wrapped in a big loop.
Impedence is generated when current flows back and forth through the coil and it interacts with the speaker magnet.
I know - too much information.

Anyways, if you are concerned that the speakers impedence doesn't match the amps, or something similar, post the details.

 

DO NOT try the resistor!!!! it has no way of dispateing heat like the speaker(frame,magnet,top and bottom plate act as a heat sink)

 

mikes dad ,what the hell are you talkin bout????? A 4 ohm speaker read resistance with a ohm meter. any where from 2-8 ohms depending on make amd model!! When the voice coll moves the resistance changes from 0-50 ohms(need a Z meter to measure while playing at a certan hz) BUT never have I or any one else made or saw a working speaker that read 0 ohms, if it dose it is shorted out (fyi the lowest ohm speaker made is .75-1 ohms for DB drag sound off ,and still read .5-1.5 ohms on a meter

 

No way to change a 4ohm speaker without reconing it (rebulding it with new parts) so if to low of impedence try trunin dow the amp-way down, if to high you kinda stuck with that.

 

Mmmm... good point Matt... I never did mention that any load box must be cooled... I just figured people were smart enough to figure that out. Either way, it needs either a heat sink, or a fan blowing across it.

And Mike's Dad... You may be some manner of electrical something, but you sure don't know speakers. Your average 4ohm voice coil reads right around 4ohms (in my personal experience between 2.8 and 5ish)

I still support getting another speaker. Everybody loves the +3dB gain.

 

yea get another speaker. Or they do have a thing called an accumatch that allows you to fool the amp. it runs about 200 bucks if you can find one. i belive its a transformer.

But it would be cheaper/ easier to get the right impence sub or just get another one.