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Forums     Plugins     GlissEQ Bandwidths relationship to Hi and Lo-Pass Filters

I am using GlissEQ with an HTPC for music playback and not for mastering.

Are the Hi-Pass and Lo-Pass filters dynamic?

How does the bandwidth affect the Hi and Lo-Pass Filters?  For example, if I use a Hi-Pass 24 Filter on the L & R channel, what should the bandwidth be for an actual 24 db/octave rolloff?  Should it be 2?  Can I change the bandwidth to make this a 48 db/octave rolloff?

Hi- and low-pass filters are not dynamic.  The "bandwidth" affects transition band of the hi- and low-pass filters.  The slope is fixed, you can't use "bandwidth" it to turn the filter into 48 dB/oct one - you have to use two 24 dB/oct bands to get 48 dB/oct slope.  The optimal bandwidth for 24 dB/oct hi-/low-pass filter is around 1.85.

Aleksey Vaneev: The optimal bandwidth for 24 dB/oct hi-/low-pass filter is around 1.85.

And the optimal bandwith for the 12 dB/oct hi-/low-pass filter?  Same?  Maybe that's some useful information to put into the Manual?

Bandwidth=1.9 is actually an even better choice.  Yes, I'm going to add this information to the user guide.


If I route Input A to Output 1 and Output 2, can I use the Hi and Lo-Pass filters to create a two-way crossover for a speaker?  I assume that if I use a bandwidth of 1.9 for each that they would combine properly.  If it doesn't work, it would be nice if you added another filter that allows for redirection of frequencies to another channel.  This would be similar to what you have in VoxengoBMS, but would allow it to be used for any frequencies.  This would also require more channels to be allowed than just eight (for a multi-channel setup).  Another commercial product that does something similar is Thuneau's Allocator XO (

No, you can't use a single plug-in instance to produce cross-over filter.  You have to use two plug-in instances (one will produce lower frequency part, the other will produce higher frequency part) For best results you should use 24 dB/oct filters with Bandwidth=1.9, tuned to the same frequency.


I've also been tinkering with glissEQ for music playback.  You can use it to do active crossovers the same way you would with Allocator, if that's what you're asking.  Create bandpass with the appropriate lowpass filter and highpass filters.

The only reason it might not work for my application is because the routing doesn't seem to allow us to split an input signal to two different groups & outputs.  But the filter/eq section itself is great.


If you can't use multiple instances of GlissEQ, you should be able to use another Voxengo plugin, such as the free Sound Delay plugin, to split the input signal.  You don't have to use the plugin for any processing, just to split the signal prior to being used by GlissEQ.  For example, in Sound Delay you could route Input A to Output A, B, & C and Input B to Output D, E & F.  Now in GlissEQ, Inputs A, B, & C are identical and can be used for a three way crossover on the left speaker.

mojave, nice tip - it should work that way, of course.
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