Stupid speaker test question...please help a n00b


Why aren't speakers tested by measuring the output sound waves vs the input wave signals? Would this not be the easiest way of testing distortion introduced by the speaker? Assuming you control all the other parameters of the test of course...

Thanks for the help!
spartanmorning
Where should they play, in a water polo pool?

I'm tempted to say that that would be roughly as useful as an anechoic chamber, but that would be a (slight) overstatement.

I never said that I had a better place to measure than an anechoic chamber (other than the "right", but impractical answer: In your own listening room), I just said that an anechoic chamber is a poor environment for simulating real world performance (per Johnnyb53). If you want to make the case that any baseline is better than no baseline, I won't argue, but....

Hopefully, my point was understood: Anechoic measurements may be the most logical way to measure a speaker, but IME, they're not very useful for predicting in-room performance. By the way, "not very useful" isn't the same as "useless". Above 250hz or so, smooth anechoic FR usually translates to smooth in-room response in that region. Below 150hz, IME, anechoic response is pretty much useless. Again, IME, for predicting critically important (to me) octave to octave balance, anechoic FR only weeds out the really bad desgns.

This thread has morphed into the question of which measurements might be useful in evaluating speakers - and my conclusion is that, generally, anechoic FR is of sharply limited utility.

Marty
The vast majority of music is above 150 Hz. Even with the diversity that exists in most real listening environments, having a baseline at least lets one try to correct for it.
Unsound,

While I completely agree with your observation re: vast majority of music lies >150hz, the octave to octave balance of a speaker is priority one for me. If the 3 octaves (or so) below 150hz aren't well balanced with the remainder of the speaker's bandwidth above, I won't be able to live with that speaker. To me, this concern is far greater than midband accuracy, imaging, dynamics, etc.

Anechoic response is often used to demonstrate how well balanced a speaker is from bottom to top. IME, once you get that speaker into a listening room, the story is wildly different.

Marty

PS I now use Audyssey on my 2.2 channel main system for this reason. It eliminates the guesswork.
I think products like the Audyssey just might well be the game changer in the near future. Still, knowing what a speakers low frequency output is in an anechoic chamber gives one advantages when making an initial purchase. Even room correction can't make a speaker do what it's not capable of. Truth be told, I doubt most manufacturers have access to anechoic chambers that are accurate below 200 Hz. I suspect most use computer modeling to predict anechoic response that low down in frequency. As compromised as that might be, it still allows for apple to apple comparisons, that can be user modified as needed.
I agree with a lot of your observations here. However, (whether true or "quasi" - and, as you note, it's often hard to say how the numbers came to be) the anechoic data that I've seen published for speakers has not been very useful for my main FR concern - determining that a speaker has an acceptable octave to octave balance in my room.

The published data has had little (if any) correlation to what I hear (and measure, for that matter) in my own listening room. Obviously, I can't speak to your experience applying this data. If you find it useful in "apples to apples" comparisons, that's great. I just can't say that it's been useful FOR ME in that regard.

Marty