Linkwitz-Riley multiple crossovers proximity
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- KVRer
- Topic Starter
- 3 posts since 11 Dec, 2014
How can I minimize the effect of setting up crossover frequencies too close to each other?
This is a 4th order LR. With 8th it's even worse. This is with unity gain of all the split bands. What did I miss here ?
This is a 4th order LR. With 8th it's even worse. This is with unity gain of all the split bands. What did I miss here ?
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- KVRer
- Topic Starter
- 3 posts since 11 Dec, 2014
Yes I do. This is a 4 band scenario, so if my understanding is correct:
- band1 needs to be filtered with allpass2(=lp2+hp2) and with allpass3(=lp3+hp3),
- band2 needs to be filtered with allpass3
Then to recombine the bands, I do band4+ band3 + allpassed(band2) + allpassed(band1)
Look at the frequency response when crossover frequencies are far away - things are as expected then.
- band1 needs to be filtered with allpass2(=lp2+hp2) and with allpass3(=lp3+hp3),
- band2 needs to be filtered with allpass3
Then to recombine the bands, I do band4+ band3 + allpassed(band2) + allpassed(band1)
Look at the frequency response when crossover frequencies are far away - things are as expected then.
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- KVRian
- 1273 posts since 9 Jan, 2006
When you split from 2 to 3 bands then band 1 needs allpass filtering. Splitting again from 3 to 4 bands then band 1 and 2 will need allpass filtering. So band 1 needs filtering by both allpass filters in other words
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- KVRAF
- 1606 posts since 12 Apr, 2002
From the graph is still looks like phasing artifacts. 4th order filters have 0 deg phase shift in pass and stopbands, which could explain why you're not getting them when the filters are far apart. Are you sure your order of splitting the bands corresponds to the order of allpass filtering?
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- KVRian
- 832 posts since 21 Feb, 2006 from FI
Two constructions introduced here by Martin Eisenberg - https://www.dsprelated.com/showthread/c ... onological
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- KVRian
- 1273 posts since 9 Jan, 2006
Yup, what I describe is figure 4b in his comment. 4a seems a smart optimizationjuha_p wrote: ↑Thu Oct 11, 2018 8:38 amTwo constructions introduced here by Martin Eisenberg - https://www.dsprelated.com/showthread/c ... onological