18 replies to this topic

[Pulse-R]

I can tell the difference if the midbass is pushing or pulling at my trouser, but usually by looking at the speaker moving - does it move in or out on a kick drum?. Absolute phase is interesting.. yes you can tell the difference, but which is correct? Since sources can also have different absolute phase. microphone to recorder, for instance - there are some who say that the phase from the mic should be reversed to feed the recorder, and some mics have correct and others incorrect absolute phase.

here's a supplementary question: "Does the natural roll-off of a speaker outside its usable range also impart a phase shift on the acoustic system? And if so, is it something we should allow for in our crossover design?"

hah
! no hints

[br85]

Pulse-R, on Feb 19 2008, 09:28 PM, said:

here's a supplementary question: "Does the natural roll-off of a speaker outside its usable range also impart a phase shift on the acoustic system? And if so, is it something we should allow for in our crossover design?"

hah
! no hints

It shouldn't impart a phase shift, but even if it does, pretty much all crossovers are in effect by a reasonable level by the time we hit the natural roll-off "zone" since ideally, and most often in practice too, we will be using another driver to squirt out the signal in that frequency range. Makes me a little iffy about first order crossovers though if there is a phase shift at those ranges...

[~thematt~]

AFAIK, roll-off does induce phase-shift, but that shift is part of the natural shift of the driver across its bandwidth. I do know it needs to be accounted for in the construction of passives.

Dyn is one such company where, in their home audio units at least, the crossover is designed to complement the woofer in both slope and phase at the Xover point.

[syd-monster]

Great thread guys, thanks for all the input. I enjoye the POV's without the bravado...