Aw, don't mind him he's just fishing for a fight. He's all in a huff
because there is no such thing as Watts RMS, even though it's (mis)used
all over the place. Whenever you think to write Watts RMS, just replace
the "RMS" with "average sine-wave power" and you'll probably not set off
the local land-mines. ;-)
What's wrong with "Watts RMS?" It's a standard electrical
Please drop the "audiophool" comments if you wish to post to
alt.engineering.electrical. That may be the posting style in
the rec.audio.car groups, but here in alt.engineering.electrical
we like to talk about electronics without flaming each other.
This group (alt.engineering.electrical) does have *engineering*
in it's title. And by the way Tony, "average sine-wave power" is
also meaningless. It's *average power*, depending on the failure
mechanism "average" may be over a wildly different time scale. Of
course there are other failure mechanisms than power.
Oh, good god no! RMS is used for units where the square (the
'S' part) of the value is of use, like volts (square volts to get
Please understand that only such a phool would be so sloppy with
engineering terms, particularly in an engineering group.
You obviously haven't a clue. I *am* posting from
alt.ENGINEERING.electrical. I am an electrical engineer (30
years) and "WATTS RMS" is grating to my soul. It is
*meaningless*. I suggest you check your engineering degree
(perhaps at the door).
Of course. I don't know what I was thinking. I must have thought
that I was reading "volts RMS."
That's uncalled for. Anyone can make a mistake while posting.
That's also uncalled for.
That's also uncalled for.
Could we please discuss engineering without the personal attacks?
Yes. I asked that other poster to also please stop attacking people
and to please discuss engineering.
In the end it's up to us, the working engineers, to address this
problem. When someone wants to treat this newsgroupa as if it was
alt.flame instead of alt.engineering.electrical, we should put in a
polite request that they stop, and if they keep it up we should stop
replying. Flamers and trolls feed on attention.
It's from being driven to out hyperbole the competition, and marketing types
writing the ad copy without consulting, or taking the advice of their
engineering resources (but wait there's more! :-] ).
Visit one of the Home Improvement Box Stores, and check out the size of the
electric motor on a home use Air Compressor rated 5 hp, and greater. The
motor physical size being about that an honest 1 hp motor should be an
indicator for the knowledgeable buyer. The drive to sell doesn't get in the
way of honest, and meaningful, specifications. The drive to sell left a week
earlier, and is already four time zones away! :-]
Remove the two fish in address to respond
I don't think "average sine-wave power" is meaningless, especially if it
was qualified with some specific frequency, say 400Hz or 1kHz. Since
we're splitting hairs and all, I think it's more meaningful than just
saying 200W by itself. I mean if it's a 200W speaker, can I put 50V DC
at 4A into it safely? How about 1kV at 200mA? ;-) Why specifically
wouldn't it be correct to say "Watts RMS" if that's the type of V they
multiplied by A to come up with W? Should it be assumed that Vrms is
always used when calculating AC power and Watts RMS is redundant? It
just seems to me that Watts RMS actually could stand for something
specific. Should the audio world just measure it as PEP? ;-)
Yes, this is one of my pet peeves too. They come up with 'max developed hp'
so they could claim a larger number. But 'max developed' isn't the hp it
can run sustained/continous (which is how one might expect the ratings to be
based). It's something like the hp just as the thing reaches pull-out
torque and stalls. Try running the motor under those conditions and it
But does the average consumer know the difference? nope. Does Sears or any
other retailer take the time to explain it? nope. Are they all rated the
same (at least you could 'comparison shop' then)? nope. You have to spend
15 minutes reading through the fine print for such 'tricky phrases'.
You can buy detergent in the "Giant Economy Size",
the "Family Size", or whatever else the manufacturer
decides to print on the box. But what the heck do those
terms mean? "Watts RMS" is like that - a fancy sounding
term, but what the heck does it mean? To make the
Amplifier A is rated "100 Watts RMS"
Amplifier B is rated 100 Watts"
All other specs are equal.
What does amplifier A have that amplifier B does not?
Even worse, they don't specify the conditions of their "test".
Indeed I believe for their universal motors anyway, they're using
locked-rotor current times source voltage (divided by 740) as
their HP rating. ...hardly a useful number.