Stupid speaker test question...please help a n00b

>Why aren't speakers tested by measuring the output sound waves vs the input wave signals?

Because it's less relevant due to how our hearing works than other measurable parameters like intermodulation distortion and stored energy.

The phase distortion (reproduced via electronic all-pass filters so that the effects can be tested without the polar response differences that go with multiple drivers and varying cross-over functions) by cross overs through fourth order at typical frequencies is not detectable in blind comparisons with musical signals (clicks at long intervals can be differentiated).

While first order acoustic cross-overs avoid that they also allow excursion to double at a given input signal level for each octave below the cross-over point until their slope gets steeper. To avoid audible distortion as you reach the speakers' mechanical limits you need a higher cross-over point which means the lower frequency driver is becoming acoustically large with increasing directivity so there's a bigger directivity mismatch switching between drivers. You also have a +3dB peak off-axis someplace which isn't something our brains encounter in nature. I speculate that these reasons are why first order designs don't sound natural.

>Assuming you control all the other parameters of the test of course...

You'd do well to read _Sound Reproduction: Loudspeakers and Rooms_ by Floyd Toole. It does a great job summarizing what we know about hearing and sound reproduction.

Well Drew, I suspect that many of those who bought the relatively large percentage of high end speakers that have first order designs (most of which have garnered very favorable reviews along the way) considering that few companies (less than 10?) bother with the difficult task of making them, would disagree with your opinion that they "...don't sound natural."

02-21-12: Drew_eckhardt
.....I speculate that these reasons are why first order designs don't sound natural.

quite in disagreement with you on this. you clearly state you are speculating - have you heard any true 1st-order x-over speakers? Merely having a 1st-order x-over ckt does not make a speaker 1st order, just FYI.

Basically, if you create a loudspeaker to measure well in an anechoic chamber (the only way you can accurately evaluate its output), it will sound unnatural in a number of ways when placed in a room. Some loudspeakers are designed (e.g., James, Mirage, MBL, Gallo, Ohm) to interact with the room and are the better for it when it comes to natural-sounding listening. But in an anechoic chamber these speakers don't measure so well.

For nearfield monitors, anechoic measurements are valid, but for regular home audio speakers, the *power response* is more important. That is, how linear is the response when it is in a typical listening room, where walls reinforce certain bass frequencies and hard surfaces can make the treble sound unlistenably bright. If you have a narrowed dispersion at the crossover point, this won't be apparent in nearfield listening or anechoic measurement, but will sound thin and hollow at that frequency in a typical room because the narrowed dispersion at that frequency results in less reflection--and therefore less energy--there.

Please define "typical room"?