I want to learn about cone (woofer) break-up.

[GranteedEV]

Many people have downloaded Room EQ Wizard (REW), free software designed to help identify bass problems due to room reflections. It does not have an adjustable time gate - the microphone stays open and picks up all the room reflections. As a result, REW does not work as way to test speakers. Many people try anyway and get very confused by the results they get.

While something like Holmimpulse is useful to have, you can in fact use user specified gating with REW

 

[qingcong]

Gated refers to time, where the test microphone is opened and closed by computer test software over a brief timespan of a few milliseconds.

I see. So, assuming the room was reflection free, if a waveform was sent through the speaker and the mic open/closed within a short period of time, there's nothing stopping the mic from picking up all sorts of speaker harmonics right?

For example, lets say the test was done with a 1kHz signal instead of pink noise. If the speaker produced harmonics of 2k, 3k, and 4k, the resulting frequency response would have peaks at 1k, 2k, 3k, and 4k. Is this not correct?

 

[Swerd]

I see. So, assuming the room was reflection free, if a waveform was sent through the speaker and the mic open/closed within a short period of time, there's nothing stopping the mic from picking up all sorts of speaker harmonics right?

For example, lets say the test was done with a 1kHz signal instead of pink noise. If the speaker produced harmonics of 2k, 3k, and 4k, the resulting frequency response would have peaks at 1k, 2k, 3k, and 4k. Is this not correct?

Yes, a speaker's harmonic response can be detected this way.

Those higher frequency peaks will appear, just not as loud as the original 1kHz signal.

 

[qingcong]

Yes, a speaker's harmonic response can be detected this way.

Those higher frequency peaks will appear, just not as loud as the original 1kHz signal.

Right, so looking at a typical frequency response sweep, it would be impossible to know the speaker's actual response to a 1kHz signal. Meaning, if we looked at the amplitude at 1kHz, it's actually the response of the speaker to the 1kHz fundamental + harmonics from 500Hz, 250Hz, 200Hz, 100Hz, etc. Is this correct?

 

[3db]

Good post Minus. Learned lots in this thread. Thanks Swerd and Grant for posting your replies.