Newsgroups: sci.electronics.misc
Subject: Re: Power Amplifier Voltage & Current Level
References: <[email protected]>
"Lory"  writes:

> Hi,
> 
> How do you calculate the output voltage of a particular power
> amplifier model? They are most rated in watts such as
> 750W @ 4 ohm load.

The power to a load can be calculated with voltage 
and resitance values with equation

power = (U * U) / R

Where U is the voltage and R is the resistance 

This becomes U = sqrt( power * R) 
In this case the voltage with 750W @ 4 ohm load would 
be around 54.8 V. That's the RMS voltage. 
The peaks go to around +-77V. 

> I build a function generator using the IC XR2206. It's
> current is so low I can't even drive a bulb of light
> with it. So I plan to boost the voltage and current
> by plugging it to a power amplifier. 

That's a good idea. A normal audio amplifier works well 
with function generator as long as you work within the 
frequency response of the amplifier. 

> I need a voltage 10V or above. 

The amplifier you have can definately give that.

> I wonder what is the average voltage
> rating of a power amplifier. Is it dependent on the
> wattage or power rating? How do I know its respective
> voltage and current?

I answered those in the example above. 

-- 
Tomi Engdahl (http://www.iki.fi/then/)
Take a look at my electronics web links and documents at 
http://www.epanorama.net/