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Peak a boo!!


D-COOPER
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Anything other than RMS is just meaningless numbers.

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ps
So 1600 watts is the number you want to take notice of. Have a look at the Barefacedbass site for an explanation as to why 1600 watts isn't 3 times louder than your 500 watt amp.

Edited by chris_b
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When you pluck your strings they move backwards and forwards over the pickup. Just like a pendulum they are moving fastest as they cross the centre and slow down just before they reverse tracing out a pattern called a sine wave. This is turned into a voltage in the PU and then amplified to a bigger voltage by your amp. The speaker turns this into forward and backward movements tracing out the pattern of movement of your strings. The bigger the voltage your amp can swing the bigger the movement the speaker will make until it reaches its own limits.

Because the movement is peaks and troughs there isn't a constant power so we don't measure the peak it only reaches for a tiny fraction of a second, especially since the amp can be designed to produce these peaks momentarily on a test but not in real life use. Since the speaker and also the voltage go backwards and forwards in equal amounts the average position and voltage is always zero so that isn't a useful measure of power either. Instead we use a mathematical trick to calculate the average displacement of the voltage called the Root Mean Square. This corresponds also to the heating effect you would get if you passed a maximum signal from the amp through a heating element instead of a speaker. There are international standards and national ones about how you should carry out these tests.

Peak means nothing as there are hundreds of ways of cheating the system and no standards to protect you. There are 5W amps claiming to be 120W PMPO out there. Any amp manufacturer who publishes peak ratings is trying to cheat you and you should become suspicious of their RMS ratings too. These won't be lies (advertising laws in your country protect you) but they are just advertising. The truth will probably be in their manuals. The most common trick is to quote the RMS power into a speaker with low impedance which you would never use and which would overheat the amp if you did. For example my PA amp claims to be 2400W RMS but the manual states quite clearly that it gives 400W per channel continuously into the 8ohm speakers I actually use and 650W into 4ohms.

Wikipedia is pretty good on this if you want more.

Edited by Phil Starr
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