Ohms?

[Firedwarf]

I've always wondered what is meant when your amp says

400w through 2 ohms

or something.

I know ohms are the unit of measurement for resistance..but that's all.

Can anyone shed some light on the subject?

 

[Waylander]

Well, like you already know, Ohms are a measure of electrical resistance.
When it says that on your amp it means with a speaker cabinet of 2 ohms it has an output of 400 watts. With a speaker cabinet of say 4 ohms the output will be less because there is greater resistance. The usual ohmage for guitar amps is 8 or 4, it tells you 2 becaus that's the bare minimum, any less and your head'll blow.
hope that helps

 

[NAD]

To calculate your ohm load, use multiply your cabinet ohms, then divide them by the ohmage added up. Makes sense? Here's an example:

Let's say you have two 8-ohm cabs: (8*8)/(8+8) = 4 ohm load.

Another: one 4-ohm cab, one 8-ohm cab: (8*4)/(8+4) = 2.6 ohm load (approx.)

MAKE SURE THAT YOU DON'T RUN A LOAD THAT YOUR AMP CANNOT HANDLE!!! There should be a plate or sticker on that back that says "2 ohm minimum" or something similar. The lower the load, the more watts you get, but the harder your amp is working to keep up with the speakers.

 

[the alumnus]

V=IR when:
V=Volts
I=amps
R=resistance=ohms

VI=P
V=Volts
I=amps
P=power=watts

 

[FrostGiant]

I thought ohms had something to do with meditation?