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Ohms - power rating conversion?

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18 May 2011 07:53 | Quote
Joined: 22 Feb 2008
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Just looking for some help here,
I'm trying to figure out the 8ohm power rating for power amplifier that only gives spec's for 4 and 2ohm power ratings.

What I'm looking at gives 1250w@4ohms and 1500w@2ohms, however I'm running an 8ohm PA system.

How do you convert the 4ohm power rating into 8ohms? And what would it be in this situation?
Also since a rating for 8ohms isn't given does this mean the amplifier isn't capable of holding an 8ohm load (even though it is less demanding load compared to 4 and 2ohms)?

Note: The PA system won't be running in series, this is direct one output to one input.
18 May 2011 10:24 | Quote
Joined: 03 Sep 2010
United States
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well personally i havent a clue how to do it,but if you can figure this out your set.


18 May 2011 11:04 | Quote
Joined: 11 Apr 2011
United Kingdom
Lessons: 1
Karma: 12
Well watts are power and ohms are resistance

V=I/R and P=IV

Therefore the watts it will give would be equivilant to P=RV^2 or power=resistance multipled by voltage squared.

Although personally I'd treat anything you work out this with caution. Not because the equation is wrong but because I'm not 100% sure if this is the right context (AC vsDC power etc)
19 May 2011 01:54 | Quote
Joined: 22 Feb 2008
Licks: 2
Karma: 14
Cheers for the response guys, I managed to see my uni lecturer about it and from my understanding i goes like this:

all ratios referenced the power rating @4ohms.
8ohms = 100w = .5
4ohms = 200w = 1
2ohms = 400w = 2

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