Dragster Subs

...another audiophool. "Watts RMS", please!

Don't be so sarcastic. that was all i could see for wattage specs from the website. if you are gonna be rude, use google and go find the info yourself!

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 engineering term.

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 power).

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

hmm, sorry for the crosspost.

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?

He's been hanging around too much with that *other* poster that is quick to jump and begin attacking people for any misstep.

daestrom

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.

You guys are whack. If watts RMS is not used correctly then why do companies use the term around the world? On websites, product box'z and such.

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! :-]

Louis--

Engineering

(mis)used

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 burns out.

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

daestrom

Nope. This is an *engineering* group. no? As such people should be using engineering terminology correctly. Sorry if you think otherwise, dae!

LOL! You said it better than I could! Nothe that I have a 3.5HP Sears shop vac. By my numbers it should have melted that 16GA cord it has on it. ;-)

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 question plainer:

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.