...One point that I can add at this time is that the term "RMS" power or watts shouldn't be used, because there is no such thing(despite frequent use, sometimes even by manufacturers). Voltage continuously varies from about +170 to -170(in North America)and a special type of average called root mean square is used(comes out 120 volts)to show the effective overall voltage. This is used when it meets something(like a speaker voice coil) that has a resistance and results in power being used. A watt itself is a fixed amount of power and doesn't vary, so no RMS or other average is needed to express it.
As always, great info John. I never mean to doubt you, as you are a much more knowledgable man than I in this (and likely most other) area. It's just so hard to swallow some of this stuff when I've lived with what I
thought was gospel for the last few decades. It's like walking into a church, burning the bible and exclaiming, "this is a lie".... WHAT, THERE'S NO SUCH THING AS RMS???
But after looking into it I see what you mean. RMS is based on an average of a power wave, not a constant figure. Still, it seems to be pretty widely used not only in car audio, but all audio as far as I could tell. I did stumble upon some rather humorous things while looking these things up. This one in particular was enlightning...
Clicky Also, as long as it's all correct, Wikipedia had a lot of good info...
Wiki-clicky I was expecially intrigued by this statement in the 'Power and Loudness in the Real World' section...
" The sensitivity of loudspeakers, rather than merely the often-quoted power-handling capacity, is important. Many high quality domestic speakers have a sensitivity of 84 dB for 1 W at 1 meter, but professional speakers can have a figure of 90 dB for 1 W or even 100 dB (especially for some large-coned woofers). I.E., An '84 dB' source "speaker" would require a 400-watt amplifier (assuming it didn't burn out) to produce the same audio energy as a '90 dB' source being driven by a 100-watt amplifier, or a '100 dB' source being driven by a 9.92 watt amplifier(though in practice modern sub-woofers are often driven by high power amps to overcome the restriction of a small enclosure through the use of equalization). This does not mean a bigger speaker can produce more sound with less overall power. Just that a larger speaker can typically handle more initial power and so requires less amplification to achieve the same high level of output. This means using a speaker with a higher dB rating can be more advantageous as many amplifiers inevitably produce a certain amount of distortion for a given level of amplification. So, (more speaker)+(less amp.)=(same "loudness")+(less distortion)".
It got me to wondering what the M80's sensitivity is. I had thought I'd seen it on here that they were around 87 db's. But looking them up in the products section under specs the only figure I could find was the 'SPL in Room1w/1m(db): 95 dB' and 'SPL Anechoic 1w/1m(db): 91 dB'... is one of these figures the sensitivity rating?
The other interesting thing I got out of it was this...
"The term "Music Power" has been used in relation to both amplifiers and loudspeakers with some validity. When live music is recorded without amplitude compression or limiting, the resulting signal contains brief peaks of very much higher amplitude (20 dB or more) than the mean, and since power is proportional to the square of signal voltage their reproduction would require an amplifier capable of providing brief peaks of power around a hundred times greater than the average level. Thus the ideal 100-watt audio system would need to be capable of handling brief peaks of 10,000 watts in order to avoid clipping (see Programme levels). Most loudspeakers are in fact capable of withstanding peaks of several times their continuous rating (though not a hundred times), since thermal inertia prevents the voice coils from burning out on short bursts. It is therefore acceptable, and desirable, to drive a loudspeaker from a power amplifier with a higher continuous rating several times the steady power that the speaker can withstand, but only if care is taken not to overheat it; this is difficult, especially on modern recordings which tend to be heavily compressed and so can be played at high levels without the obvious distortion that would result from an uncompressed recording when the amplifier started clipping".
It was this that got me thinking the guy who was trying to talk me into a 1000 watt amp to drive my M80's with was trying to account for these 'musical peaks'. If I'm listening to my speakers at a level that pulls around 10 watts of power from my amp normally, it would take 1000 watts of power to cover these peaks. I don't know this was the reasoning behind his advice for a fact, just speculation.
