I see things like 285W(at 1.50 ohms, 80Hz, 10 % THD) to decribe a speaker. What does this mean please?

Answer 1

285w - the alleged power output.

1.50ohms - the resistance the power output is measured at. Actually, 1.50ohms is incredibly low, most speakers have their power measured at 4-8ohms. As the resistance gets lower, the power increases. It looks as if the numbers have been artificially inflated, to make the speakers sound more powerful than they really are.

80Hz - the frequency the power is measured at. Again, it should be an average over three different frequencies - using one number is just falsifying the data.

10% THD - this means 10% total harmonic distortion. The more power put through a set of speakers, the greater the THD. The industry norm for power measurement is 0.1% THD. The distortion is actually audible at 1% THD. Measuring at 10% THD is frankly meaningless, because at that level, anything coming from the speakers will just be white noise.

In truth, those speakers are around 15w-20w.

Answer 2

Most reputable high end manufactures do test specs and record them, but rarely do they advertise the actual specs, unless in generalities. The numbers game can be highly subjective and most of the stuff you would run into at say Best Buy will have the figures represent there product as superior. That retailer and the manufacture are betting that average Joe will not know how to weight a particular number and just pick the one quantize that seems the most important to him at the time.

The big one is sensitivity for speakers this should be a weighted average over the entire audio spectrum 20-20kHz but companies like Sony get a hot spot frequency (anywhere from 500-2kHz) and measure its response to make a speaker look better than it is they also measure closer than the 1m standard to fudge the numbers as well. Whereas the reputable manufacture goes with the prevailing measurement method.

Amps and receivers are a whole host of fudged numbers from some manufactures, just to make it look good on paper. There are to many ways that this can be done to discuss here.

Bottom line is that specs are not that important for most consumers to complicated to weight the numbers. Critical listening and comparison should be the way to evaluate the system for you.

Numbers that are important are, type and quantity of inputs, outputs, etc.. these should stand out over spec fudging.

Answer 3

285W refers to the power of the system. 1.50ohms refers to the impdence of the speakers and therefore the amount of power they draw from the amplifier. The lower the impedence the greater amount of power. 80hz is an audible frequency. However, I'm not sure what 10% THD means - could be Total Harmonic Distortion which is a reference to the quality of the sound you hear. The higher the THD, the worse the sound.

Answer 4

That sound more like an amp spec than a speaker. 10% THD means the amp/speaker is going to sound like crap at that power level.