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In Reply to: Re: 7.5Hz cutoff? posted by BBeck on July 4, 2006 at 08:02:23:
Hi,About the figures one could expect.
My rule of thumb is that as the resistance and impendance are equal at the cut-off point (-3db point) the phase shift is 45 degrees there, and one octave away it ougth to be half of that (22deg at 15Hz for a 7.5Hz cut of) aso. (12deg at 30Hz for 7.5Hz cut-off and 12deg at 20Hz for 5Hz cut-off).Not a great problem as it would be close to impossible to build speakers and rooms (and human beings with ears IMHO :-) ) with phase shift small enougt to detect that.
But if they add up (a two stage are out of phase and would counteract somewhat) I guess the figures could be large enough (though I doubt it as speakers often change phase 180deg of the moved air at resonance in collumns) and sertainly large enough to pose a problem if feedback is used (cut-off in the region of 2Hz would be preferable, but it is more a matter of the total shift in all reactive elements).
Anyhow one should have a rough figure of the phase shifts in ones home-buit amp - I guess that is a matter of gulid :-)
mvh /Pär
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Follow Ups
- Re: 7.5Hz cutoff? - Pär 23:14:47 07/04/06 (2)
- Re: 7.5Hz cutoff? - fred76 02:53:40 07/05/06 (1)
- Re: 7.5Hz cutoff? - Pär 04:14:02 07/05/06 (0)
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