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post #1 of 4 (permalink) Old 09-07-2016, 09:57 PM Thread Starter
Join Date: Mar 2012
Location: Stockton, CA
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change in wattage

So I seemed to have developed some kind of mental block when it comes to Ohm's law. I'm going to be hooking up an extension cabinet to my amp and I can't figure out how much power I will lose by bumping increasing the speaker load. The amp is rated 120 watts at 4 ohms. When I hook up the extension cab, the new resistance will be 12 ohms. So how much power(theoretically) will I have lost throwing the cab into the mix?
silverctr is offline  
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post #2 of 4 (permalink) Old 09-08-2016, 04:38 AM
Join Date: Jul 2014
Location: Germany
Posts: 147
Re: change in wattage

120 * 4 / 12 = 40

So it should be about 80 watts that you lose.
Jemerator is offline  
post #3 of 4 (permalink) Old 09-08-2016, 11:11 AM
Join Date: Feb 2005
Location: El Paso, TX
Posts: 2,647
Re: change in wattage

is that a 12 ohm actual rating or a 12 ohms nominal ? most 4 and 8 ohm speakers are nominally called 4 or 8 ohms, but the actual resistance is something else, usually lower.

i also assume you have an odd number of speakers you have wired up in your cab ?
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post #4 of 4 (permalink) Old 09-13-2016, 04:55 PM Thread Starter
Join Date: Mar 2012
Location: Stockton, CA
Posts: 977
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Re: change in wattage

Awesome, thanks!

It's two speakers with different ratings, one is 4 ohm the other is 8 ohm. Nominal ratings until I get a new battery for my multimeter. The amp is specifies to use no less than a 4 ohm load, so I'm wiring the speakers in series, hence the 12 ohm load.
silverctr is offline  

ohms law , power , resistance , watts

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