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Old 5th September 2003, 02:11 PM   #1
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Default I know 12 and 24 db/oct but

what about 6 and 36 db/oct crossovers, how are they laid out?
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Old 5th September 2003, 02:15 PM   #2
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A 36 dB/octave (six pole) is just two three-poles in series (with their resonant frequencies and Qs appropriately chosen). A 6 dB/octave (one pole) is just a single reactance and resistance.
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Old 5th September 2003, 02:23 PM   #3
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An active section can produce max 12 dB/octave and a passive produce 6 or 12. If you want more you have to connect sections in series.....but this is a comlex subject when it comes to more than 24 dB/octave.

Walter Jung has written good things about this and many many others. Active filters are the favourite subject at unversities but many of those people haven't build anything just cretaed theories and beautiful formulas. The opamps used are often "ideal".

Walter Jung on the contrary has written about practical circuits and the latest book is here which is very good and for free.
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Old 5th September 2003, 04:14 PM   #4
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IF you are talking about speaker driver filters, it's hard to get a 6 dB per ocative effective rolloff when using typical drivers in typical configurations. 6 dB per octave is quite shallow and covers a lot of the audio band before significant attenuation occurs. To get a 6 dB/octave acoustical rolloff, your driver needs to be flat significantly past the filter knee. In my experience with drivers, this is rarely the case. The driver may be flat where the filter starts filtering, but eventually the driver starts rolling off itself (at at least 6 dB per octave) and you get an effective rolloff at a much higher order.

Sheldon
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Old 5th September 2003, 05:49 PM   #5
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Thanks guys, I am looking to use the 6 db/oct slope on some Dynaudio speakers. That's what Dyn uses on all their speakers, so I thought I would give it a try. And yes I am interested in and electronic crossover, not a passive.
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