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Re: Average, RMS and Power Factor made easy!



Original poster: "35045 by way of Terry Fritz <twftesla-at-uswest-dot-net>" <free0076-at-flinders.edu.au>



On Wed, 10 Jan 2001, Tesla list wrote:

> Original poster: "Albert Hassick by way of Terry Fritz
<twftesla-at-uswest-dot-net>" <uncadoc-at-juno-dot-com>
> 
> Hi members.  But does not R.M.S. power have significance when used as a
> means of rating various electrical components such as loudspeakers and
> power amplifiers?  And would not these same ideas apply to a Tesla  coil?

You're right in saying that many manufacturers rate audio equipment in
Watts RMS but they are misusing the term RMS. Many manufacturers use PMPO
which stands for Peak Music Power Output. According to a sound engineer I
know, the manufacturers can get away with better sales to idiots with
money by selling 1000W PMPO amps for cars etc. What PMPO means according
to him, is that they got that power output for a split second just before
they damaged it =) Essentially the more honorable products quote the
average power but often they use RMS which is strictly not correct.
Probably 'average power' makes the buyers even more uneasy than PMPO does
=)

>  After all, a loudspeaker is a coil within a magnetic field that becomes
> excited when a voltage is applied to it, just like a Tesla coil.  And we

They are completely different. The only thing in common is the coil of
wire.

> all know how terrible our sound equipment begins to sound once we have
> exceeded the R.M.S. value of the rated components.      AL.


Thanks for bringing it to our attention. Yes, they often do say RMS power.
No, they are abusing the term RMS.

Have fun,
Darren Freeman