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Tweakers' Asylum Tweaks for systems, rooms and Do It Yourself (DIY) help. FAQ. |
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Tweakers' Asylum Tweaks for systems, rooms and Do It Yourself (DIY) help. FAQ. |
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In Reply to: Crossovers how do you find the the frequencies posted by peter on May 5, 2000 at 15:29:58:
Hi,Boy you have reached the part of speaker design that makes or breaks the performance of the system. And that's what we have to think about here, a system approach. In a perfect world, the box, driver, and crossover must be choosen and designed together, all at once.
You have a problem in that without being able to do anechoic measurements of the raw performance of each driver in the cabinet with out filters, it is going to be tough to design a crossover for it without a good imperical knowledge of how filters perform in the real world.
Your choice of a 2nd-order filter is a little odd. The reason being is that 2nd-order filters in a three-way system will produce moderate to severe frequency response errors in a Linkwitz-Riley configuration and in Butterworth the errors are even greater in a two-way and higher.
One of the problems facing loudspeaker designers is that most filters in use today do not provide a flat frequency response and the same holds true for delay response. Another fact is that these problems appear in two-way designs and become increasing worse as you go up to three-way or higher level systems. The best filter in terms of summed response, both in terms of frequency and delay, is the 1st-order Butterworth. You can use a 1st-order Butterworth if you choose your crossover frequencies well within the range of the drivers. This means that the response of the drivers must overlap considerably in order to acommodate the th gentle 6dB/octave slope. This must be particularly true for the tweeters.
For tweeters it may be a better idea to use a 1st Order Series (Quasi Second order) filter. They provide the same near flat response with a near 12db/octave near the crossover but then revert to a 6dB/oct slope futher away from the crossover frequency.
It is better to choose your drivers in accordance with the filters you are going to use (and visa-versa) and then design the cabinet around these drivers, so you are limited in this case and this is why you are having trouble.
I hope this helped. Any other questions feel free....
John LeVasseur
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Follow Ups
- Re: Crossovers how do you find the the frequencies - jrlaudio 08:38:45 05/07/00 (1)
- Re: Crossovers how do you find the the frequencies - peter 14:34:19 05/18/00 (0)
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