I was lookin at an 80w 4 way amp for my speakers on cruthfield and they say it can be ran at 80w RMS at 4 ohms, 125W RMS at 2 ohms, or 225W RMS x 2 bridged output at 4 ohms

How do you change from 4 to 2 or 2 bridged at 4 ohms etc?

http://www.crutchfield.com/S-uUrNmWZ...20&I=489AP1040

 

running 2 ohms would entail connecting two 4ohm speakers in parralell (sp) to the same output, basically chaining them .

 

On most amps, lets say a 2 channel amp, you would run lets say your positive speaker lead from the left channel and the negative from the right channel. When you do that it reduces the ohm's to 2ohm. If you have dual voice coil subs you can bridge them on the sub itself, but itll drop the ohms again to 1ohm. MOST amps are NOT 1ohm stable (rockford fosgate and macintosh amps are), youll either blow the amp itself OR blow fuses like crazy.
Im not sure where theyre coming up with the 225 watts. If the amp is 80 per channel, you should be able to bridge it to 160 for the left channnel and 160 for the right channel. The 225W must be PEAK power per channel, not RMS. So 320 total, unless theyve change how they rate amps, their math doesnt add up. BTW, that would be a 2ohms also, not 4.
-P.

 

ohms does not have to do with bridging the connection, which is what p zero is talking about. that just centrallizes your power to one connection, like when you bridge a connection to connect a sub in mono. if you want to have you amp work at a certain ohm rating, buy speakers to complement it. if you connect a 4 ohm speaker, then you get the power your amp will put out at 4 ohm. and the same with 2 ohm. different wiring setups (usually of subs) can result in your setup having a different impedance(number of ohms). so there is no switch on the amp if thats what you were owndering. you need to wire your speakers so it causes an impedance of 2 or 4 ohms to the amp. whichever one you want. crutchfeild has diagrams of how to do that depending on whether you have single or dual voice coil speakers. just search wiring diagrams on the site.

 

Another good resource is http://www.the12volt.com

 

You could always change the VC on the driver. lol

 

http://mobile.jlaudio.com/support_pages.php?page_id=145

that an in depth explanation of how to wire whatever you have to generate every resulting ohm rating possible.