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 26th July 2003, 04:18 PM #1 smithsonga   diyAudio Member   Join Date: Mar 2003 Location: Atlanta, GA area Subwoofer Alignments - Please Explain Can someone explain to me the significance of the different subwoofer alignments? Specifically the different Q alignments...sometimes they are named, sometimes not. (sealed examples of Bessell, butterworth, chebychev or the vented alignments of EBS, SBB4 etc.) Are these recommended Q values for driver/enclosures or purely guidelines etc? Someone please explain the theory and reasoning behind these different alignments. Thanks! Jim
 27th July 2003, 12:23 AM #2 Ron E   diyAudio Member     Join Date: Jun 2002 Location: USA, MN They are mathematical abstractions, which were more useful in the age before personal computers when it was difficult to run a simulation and plot the results. They still make excellent starting points. QB3/SQB3 - Quaasi third order butterworth B4 - butterworth 4th order - maximally flat amplitude BE4 - Bessel 4th order - maximally flat delay SC4/C4 - chebyshev equiripple SQB3 and C4 are nonflat alignments. SQB3 has a peak and C4 has ripples near cutoff. B4 and BE4 are only valid at one Qts value for a given amount of losses. for Ql=infinity, B4 is at Qts=0.3827, alpha=1.414, h=1 for Ql=7: Qts=0.4048, alpha= ~1 and h=1. Calculation is not trivial, but is explained in JAES by Small in the early 70's. Don't get tied to alignments, they are not required for good sound. __________________ Our species needs, and deserves, a citizenry with minds wide awake and a basic understanding of how the world works. --Carl Sagan Armaments, universal debt, and planned obsolescence--those are the three pillars of Western prosperity. —Aldous Huxley
 27th July 2003, 12:30 AM #3 SY   On Hiatus     Join Date: Oct 2002 Location: Chicagoland Dickason explains this and the tradeoffs in the Loudspeaker Design Cookbook, with lots of useful charts, graphs, and tables. If you know the stuff in there, it will dramatically narrow down your sim work and actual measuring and cutting. __________________ "You tell me whar a man gits his corn pone, en I'll tell you what his 'pinions is."

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