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I've been gone for a while, learning about time coherency and phase shift. Now I only read SQ and Advanced.
Anyway, I know passives have 6db x-overs pretty often, but how come electronic ones don't? After reading the white papers on a couple very cool speakers, I realize 72db crossovers are mathematically retarded.
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Posts: 323 | From: Great Falls, Montana | Registered: Feb 2000
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First of all some do have although they are not the best ones. I think that 6dB/oct. is not applicable for "normal" crossovering (one driver per band) but is very usefull for some special systems with for example two midbass drivers per side. In this case it would provide a smooth curve from midrange to midbass and further to the sub. But in this case it is better to use just a coil. IMHO.
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Posts: 58 | From: Hämeenlinna, Finland | Registered: May 1999
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The only real drawback to first order networks is that you need substantially higher highpass Xover points than with steeper slopes. If the corresponding driver is crossed over with this in mind though, it is no big deal...
I'm getting a real itch to do a car with a Power 1000a2 and a ton of passives....
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I don't have anything against other slopes. Heck, the speakers I'k pawing after now (JBL studio series) don't use 6db x-overs, and aren't time-aligned. They sound friggin great to me! And I hate JBL to boot!
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Posts: 323 | From: Great Falls, Montana | Registered: Feb 2000
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Here is how I am using the 1st order cross:
I have a tweeter, mid and two midbasses per side. All crossed actively at 18dB/oct. After first tweeking I faced the problem - the step between the mid and midbass was two steep. I tried to reduce a bit power from midbass but then it sounded good only in the garage, when driving midbass was not heard. Then I tried the tip used by some home speakers: I put a 6dB/oct low pass filter to one of two midbasses with the LP crossover frequency equal to HP frequency of the midbass. Thus I've got one midbass playing from 60Hz to 400Hz with 18dB/oct at both ends. Another - from 60Hz (18dB/oct) and then all the way up at 6dB/oct with -3dB at about 85Hz. Now the RTA is very linear from 20KHz down to 125Hz and then it rises smoothly.
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Posts: 58 | From: Hämeenlinna, Finland | Registered: May 1999
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