From ba_mbino@yahoo.com Tue Jul 03 07:53:50 2012
Subject:Re: Alto amps - Peak Power and RMS

and here is the engineer in me....

I agree that for a sine it is peak_voltage = sqrt(2) * RMS_voltage

However, any reputable electrical circuits/electrical network analyis will tell you that if you calculate power the formula is one of the two:
1) RMS: power = RMS_voltage * RMS_current
2) peak: power = 1/2 * (peak_voltage * peak_current) 
(the fact that you can find it on books does not mean that people use this formulas correctly, especially when some "sales person" plays the engineer and want to "inflate" the spec sheet of his/her product)
In short, if correct formulas were applied, peak or RMS should lead to the same electrical wattage. 

Having said that, when talking about amplifiers (as Bruce and others said) electrical wattage is not what you should be looking for (or at least it should be just one of the factors). Other parameters are definitely more relevant.

-Marco

________________________________
From: Bruce Wahler
To: CloneWheel@yahoogroups.com
Sent: Tuesday, July 3, 2012 9:40 AM
Subject: Re: [CWSG] Re: Alto amps - Peak Power and RMS


 
> Peak is never 1.414x1.414 x RMS

[My apologies for turning this into an engineering discussion...]

I'm sorry but I have to disagree. The peak value of a 1V (RMS) sine
wave is 1.414V, and the peak-to-peak is 2.828V. Power is V^2 / R. So,
if we pretend that we have a 1-ohm speaker to make the calculations easier:

Power = (1)^2 / 1 = 1W RMS

Power = (1.414)^2 / 1 = 2W Peak

The speaker impedance will not change, and that's a 2:1 ratio in my book
-- or am I missing something?

Regards,

-BW

Bruce Wahler
Ashby Solutions.com^(TM)
bw@ashbysolutions.com
http://music.ashbysolutions.com
877.55.ASHBY (877.552.7429)

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