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Well, THAT's Not Gonna Fucking Work!
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<blockquote data-quote="Peter Morris" data-source="post: 39828" data-attributes="member: 652"><p>Re: Well, THAT's Not Gonna Fucking Work!</p><p></p><p></p><p></p><p>Hi Mark,</p><p></p><p><span style="font-family: 'Arial'"><span style="color: #000000">FWIW, for some reason I think that some the DBX stuff is similar to the BSS … anyway this is what the BSS omini drive compact manual says regarding phase.... </span></span></p><p></p><p><em><span style="font-family: 'Arial'"><span style="color: #000000">A classic 2-Way crossover using just a high-pass and a low-pass filter will</span></span></em></p><p><em><span style="font-family: 'Arial'"><span style="color: #000000">always meet the criteria predicted for a given alignment. A 2-Way Linkwitz-</span></span></em></p><p><em><span style="font-family: 'Arial'"><span style="color: #000000">Riley crossover ,for example, will produce its two outputs 'everywhere in</span></span></em></p><p><em><span style="font-family: 'Arial'"><span style="color: #000000">phase', and they will acoustically combine to a flat amplitude response. The</span></span></em></p><p><em><span style="font-family: 'Arial'"><span style="color: #000000">main lobe of the polar response will also be on-axis.</span></span></em></p><p><em><span style="font-family: 'Arial'"><span style="color: #000000">When more filters are added to the crossover for more than two drivers,</span></span></em></p><p><em><span style="font-family: 'Arial'"><span style="color: #000000">however, the crossover begins to depart from the mathematical perfection of</span></span></em></p><p><em><span style="font-family: 'Arial'"><span style="color: #000000">the 2-Way case. In a 3-Way crossover, the high-pass characteristics of the mid</span></span></em></p><p><em><span style="font-family: 'Arial'"><span style="color: #000000">band will be disturbed by the phase response of the low-pass in the mid band,</span></span></em></p><p><em><span style="font-family: 'Arial'"><span style="color: #000000">and vice-versa. This results in drivers of adjacent bands being driven out of</span></span></em></p><p><em><span style="font-family: 'Arial'"><span style="color: #000000">phase, producing irregularities in the amplitude response, and pushing the</span></span></em></p><p><em><span style="font-family: 'Arial'"><span style="color: #000000">main lobe of the polar response off-axis, further aggravating amplitude</span></span></em></p><p><em><span style="font-family: 'Arial'"><span style="color: #000000">response problems in some listening positions. Although these effects may be</span></span></em></p><p><em><span style="font-family: 'Arial'"><span style="color: #000000">subtle when the crossover frequencies are well separated, 4 and 5-Way</span></span></em></p><p><em><span style="font-family: 'Arial'"><span style="color: #000000">systems can produce significant errors.</span></span></em></p><p><em><span style="font-family: 'Arial'"><span style="color: #000000"><u>The phase compensation scheme employed</u> in the FDS-355 analyses these</span></span></em></p><p><em><span style="font-family: 'Arial'"><span style="color: #000000">phase anomalies whenever adjustments are made, and introduces phase</span></span></em></p><p><em><span style="font-family: 'Arial'"><span style="color: #000000">adjustment into certain bands such that the phase difference between all</span></span></em></p><p><em><span style="font-family: 'Arial'"><span style="color: #000000">adjacent bands is always close to zero degrees. It will of course allow the user</span></span></em></p><p><em><span style="font-family: 'Arial'"><span style="color: #000000">to introduce intentional phase differences, using the <em>phase </em>and <em>delay</em></span></span></em></p><p><em><span style="font-family: 'Arial'"><span style="color: #000000">parameters. The FDS-355 will not attempt to apply phase compensation if the</span></span></em></p><p><em><span style="font-family: 'Arial'"><span style="color: #000000">high and low frequencies or shapes of the adjacent bands do not match, on</span></span></em></p><p><em><span style="font-family: 'Arial'"><span style="color: #000000">the assumption that the user does not expect to produce a standard alignment.</span></span></em></p><p><em><span style="font-family: 'Arial'"><span style="color: #000000"></span></span></em><em><span style="font-family: 'Arial'"><span style="color: #000000"></span></span></em></p><p><em><span style="font-family: 'Arial'"><span style="color: #000000"></span></span></em>Peter</p></blockquote><p></p>
[QUOTE="Peter Morris, post: 39828, member: 652"] Re: Well, THAT's Not Gonna Fucking Work! Hi Mark, [FONT=Arial][COLOR=#000000]FWIW, for some reason I think that some the DBX stuff is similar to the BSS … anyway this is what the BSS omini drive compact manual says regarding phase.... [/COLOR][/FONT] [I][FONT=Arial][COLOR=#000000]A classic 2-Way crossover using just a high-pass and a low-pass filter will[/COLOR][/FONT][/I] [I][FONT=Arial][COLOR=#000000]always meet the criteria predicted for a given alignment. A 2-Way Linkwitz-[/COLOR][/FONT][/I] [I][FONT=Arial][COLOR=#000000]Riley crossover ,for example, will produce its two outputs 'everywhere in[/COLOR][/FONT][/I] [I][FONT=Arial][COLOR=#000000]phase', and they will acoustically combine to a flat amplitude response. The[/COLOR][/FONT][/I] [I][FONT=Arial][COLOR=#000000]main lobe of the polar response will also be on-axis.[/COLOR][/FONT][/I] [I][FONT=Arial][COLOR=#000000]When more filters are added to the crossover for more than two drivers,[/COLOR][/FONT][/I] [I][FONT=Arial][COLOR=#000000]however, the crossover begins to depart from the mathematical perfection of[/COLOR][/FONT][/I] [I][FONT=Arial][COLOR=#000000]the 2-Way case. In a 3-Way crossover, the high-pass characteristics of the mid[/COLOR][/FONT][/I] [I][FONT=Arial][COLOR=#000000]band will be disturbed by the phase response of the low-pass in the mid band,[/COLOR][/FONT][/I] [I][FONT=Arial][COLOR=#000000]and vice-versa. This results in drivers of adjacent bands being driven out of[/COLOR][/FONT][/I] [I][FONT=Arial][COLOR=#000000]phase, producing irregularities in the amplitude response, and pushing the[/COLOR][/FONT][/I] [I][FONT=Arial][COLOR=#000000]main lobe of the polar response off-axis, further aggravating amplitude[/COLOR][/FONT][/I] [I][FONT=Arial][COLOR=#000000]response problems in some listening positions. Although these effects may be[/COLOR][/FONT][/I] [I][FONT=Arial][COLOR=#000000]subtle when the crossover frequencies are well separated, 4 and 5-Way[/COLOR][/FONT][/I] [I][FONT=Arial][COLOR=#000000]systems can produce significant errors.[/COLOR][/FONT][/I] [I][FONT=Arial][COLOR=#000000][U]The phase compensation scheme employed[/U] in the FDS-355 analyses these[/COLOR][/FONT][/I] [I][FONT=Arial][COLOR=#000000]phase anomalies whenever adjustments are made, and introduces phase[/COLOR][/FONT][/I] [I][FONT=Arial][COLOR=#000000]adjustment into certain bands such that the phase difference between all[/COLOR][/FONT][/I] [I][FONT=Arial][COLOR=#000000]adjacent bands is always close to zero degrees. It will of course allow the user[/COLOR][/FONT][/I] [I][FONT=Arial][COLOR=#000000]to introduce intentional phase differences, using the [I]phase [/I]and [I]delay[/I][/COLOR][/FONT][/I] [I][FONT=Arial][COLOR=#000000]parameters. The FDS-355 will not attempt to apply phase compensation if the[/COLOR][/FONT][/I] [I][FONT=Arial][COLOR=#000000]high and low frequencies or shapes of the adjacent bands do not match, on[/COLOR][/FONT][/I] [I][FONT=Arial][COLOR=#000000]the assumption that the user does not expect to produce a standard alignment. [/COLOR][/FONT][/I][I][FONT=Arial][COLOR=#000000] [/COLOR][/FONT][/I]Peter [/QUOTE]
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