[macrae11]

Wayne A. Pflughaupt wrote:

Assuming Rod Elliot was referring to equalization, we get a contrasting (conflicting?) view from Rane’s Exposing Equalizer Mythology by Dennis Bohn (bold emphasis added):

“Phase shift is not a bad word. It is the glue at the heart of what we do, holding everything together. That it has become a maligned term is most unfortunate. This belief stands in the way of people really understanding the requirements for room equalization.

Associated with each change in amplitude is a corresponding change in phase response. Describing them as unbelievably jagged is being conservative. Every time the amplitude changes so does the phase shift. In fact, it can be argued that phase shift is the stuff that causes amplitude changes. Amplitude, phase and time are all inextricably mixed by the physics of sound. One does not exist without the others.”

I think what Mr. Elliot failed to consider is that equalizers also introduce phase changes, which probably accounts for how it’s usually possible to EQ phase-related response problems around a sub’s crossover region.

Overall though, that was a very good article. Thanks for linking it. I especially liked the part about mics not "hearing" the way our ears do. That's probably why you don't get much of an audible improvement equalizing subs beyond smoothing out the worst problems. I.e., piling on lots of "minutiae" filters smoothing out every little ripple in response you probably won't be able to hear the difference with them in or out. I sure can't.

Regards,
Wayne

You are correct, but I belive Mr. Elliot was thinking on a slightly different line. Of course when dealing with EQ's amplitude and phase are related(with the exception of a linear phase EQ). In the real world(no EQ) they are not so incontrovertably linked. You can have the identical phase of two signals with two completely, even opposite amplitudes. Also the time which Mr. Elliot and yourself are referring to are on different scales. a 10 degree phase shift at 80 Hz (wavelenghth of 4.2m) takes a little over a 1000th of a second. Room nodes can cause differences in time of an 80Hz note of a second or more. So an EQ(even a very poor "phasey" EQ) can come nowhere close to adjusting that kind of time.

PS. Someone please correct me if my math is wrong, it's been quite some time since I've had to work out any formulas.