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<blockquote data-quote="helotaxi" data-source="post: 2974795" data-attributes="member: 550915">Lots of variables here and you guys have covered (partially) one of them.First you have to understand what the frequency of the filter means.&nbsp; The &quot;cutoff&quot; freq of the filter and the number that you are setting is the &quot;half power&quot; point or the frequency at which the filter has reduced the level of the signal by 3dB.Second, for the signal to be down 3dB at the filter freq, then the filter must be affecting the lower freqs as well.&nbsp; Most filters (depends on the order and type of the filter) will begin attenuating the signal an octave away from the nominal filter freq.&nbsp; This means that you 100hz filter is affecting the signal as low as 50hz.&nbsp; Changing the slope of the filter to a higher order can minimize this.Example:<img src="http://img219.imageshack.us/img219/180/crossoverplotxz4.jpg" alt="" class="fr-fic fr-dii fr-draggable " style="" />The 4 plots here are all the same sub in the same box and will help explain the effects of the different filter freqs and slopes.&nbsp; The white curve is the sub with no filter.&nbsp; The red curve is same sub with a 50hz 12dB/oct. filter applied.&nbsp; The blue curve is a 50hz 24dB/oct filter.&nbsp; The yellow curve is a 100hz 12dB/oct filter.Notice that the red curve is 1dB below the unfiltered response at its peak and it peak is below the LPF freq.&nbsp; Notice how the steeper filter at the same freq is .5dB louder than the first and its peak freq has shifted closer to the filter freq.&nbsp; Finally note how the higher freq allows the sub to reach its potential in the region below 70hz.&nbsp; Neither of the other filters did this.&nbsp; The 40-70 hz region is where most rock and hip-hop bass is centered.&nbsp; Setting your LPF too low will limit the ability of the sub to get loud in this region.&nbsp; Steepening the slope will allow a lower filter freq with minimized effects below the filter freq.</blockquote>

[QUOTE="helotaxi, post: 2974795, member: 550915"] Lots of variables here and you guys have covered (partially) one of them. First you have to understand what the frequency of the filter means. The "cutoff" freq of the filter and the number that you are setting is the "half power" point or the frequency at which the filter has reduced the level of the signal by 3dB. Second, for the signal to be down 3dB at the filter freq, then the filter must be affecting the lower freqs as well. Most filters (depends on the order and type of the filter) will begin attenuating the signal an octave away from the nominal filter freq. This means that you 100hz filter is affecting the signal as low as 50hz. Changing the slope of the filter to a higher order can minimize this. Example: [IMG]http://img219.imageshack.us/img219/180/crossoverplotxz4.jpg[/IMG] The 4 plots here are all the same sub in the same box and will help explain the effects of the different filter freqs and slopes. The white curve is the sub with no filter. The red curve is same sub with a 50hz 12dB/oct. filter applied. The blue curve is a 50hz 24dB/oct filter. The yellow curve is a 100hz 12dB/oct filter. Notice that the red curve is 1dB below the unfiltered response at its peak and it peak is below the LPF freq. Notice how the steeper filter at the same freq is .5dB louder than the first and its peak freq has shifted closer to the filter freq. Finally note how the higher freq allows the sub to reach its potential in the region below 70hz. Neither of the other filters did this. The 40-70 hz region is where most rock and hip-hop bass is centered. Setting your LPF too low will limit the ability of the sub to get loud in this region. Steepening the slope will allow a lower filter freq with minimized effects below the filter freq. [/QUOTE]

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