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
"I have to say I find this field of 'hi-fi' quite frustrating"

You're not alone. We are here to learn.
IMHO, John Dunlavy built some of the finest loudspeakers, and he depended on tests more than most. He seemed to think that step and pulse response were particularly important.
Square wave reproduction (as noted by Unsound) is a darned good objective test. Decades ago Ohm cited this in their promotional material. I have been told that a few other speakers pass this test.
One limiting issue in hifi is measurement vs perception.
Apparently, everything that can be measured doesn't matter and some things which matter are not measured...or perhaps measurable (yet). Add in literally hundreds of tweaks ranging from Schumann frequency generators to having a Seance before listening doesn't help much, either.

Toss in a good mix of those in favor of DBT, SBT and whathaveyou and you've got a real mess.

Contentions that 'amplifiers run in there linear, non-clipping area all sound alike' without reference to what speaker is being driven, don't necessarily help.

'Ya can't take it TOO seriously because 'that way lies madness'.

Some of what would seem to be basic advice like....listen before buying or find a good sales guy to trust and work with.....may not help because a person new to this 'hobby' doesn't necessarily know who to listen TO or what to listen FOR.

Advanced HIFI does a poor job of selling itself, but that's another thread.
I'm not so sure about squarewave testing being meaningful. It will reward first order (analog) x-over designs, but the audible benefits are debateable. I won't take sides in that debate, but Siegfried Linkwitz has written extensively on the subject, and he comes down squarely (pardon the pun) on the side of higher order designs that won't fare as well on squarewave tests.

Linkwitz certainly qualifies as an authority, since the Linkwitz-Riley crossover solution (even order only for "true" L-R, odd order "quasi" L-R is possible for 3rd order and above) is pretty widely considered a classic bit of design theory. Obviously, there are great designers (Dunleavy, Vandersteen, et al) out there using first order crossovers so.....

While L-R is NOT universally accepted as an optimal solution, Linkwitz's analysis does cast some doubt on the real world benefits of goood performance on a squarewave test.

Marty

PS For those pointing out that THD tests, etc. are of limited utility in judging a speaker's performance, I'd say that this is one more example where test results for speakers may raise more questions than they answer.