2500 hz hump [message #48390] |
Tue, 13 December 2005 16:33 |
Paul C.
Messages: 218 Registered: May 2009
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Master |
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Wayne, besides the woofers you use in Pi's, I have been looking at other similar high efficiency woofer. It seems that most have a hump or peak in the 2000 hz range, then fall off. Examples are Eminence Gamma 12, Some the hump is quite mild, Eminence Delta 15LF, Delta 12LF, Gamma 15. What causes this peak? Is there any way to tame this in the crossover?
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Re: BTW.... [message #48398 is a reply to message #48396] |
Wed, 14 December 2005 20:04 |
Paul C.
Messages: 218 Registered: May 2009
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Master |
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Yes, they should cross over before that 2000 hz-2500 hump. But even with the crossover rolling them off, they still may have a high peak that interferes with getting an accurate xover. With some, even with 12 db/oct, this peak makes them unsuitable for the 1600 hz xover freq recommended for the Eminence PSD2002. A 2-way will not work for these, you would have to go much lower, and probably go to a 3-way system.
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Re: BTW.... [message #48401 is a reply to message #48398] |
Thu, 15 December 2005 07:57 |
Spinjack
Messages: 100 Registered: May 2009
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Viscount |
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Can you not just set the crossover point such that the signal rolls off just before the hump which combined with the hump gives relatively flat total response until the back side of the hump where the total rolloff is now steeper than 12db/oct? You would have to design the system for a steeper rolloff total on the back side of the hump. (Forgive me is I'm way off base. I'm still rather new at this.)
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bad breakup [message #48409 is a reply to message #48401] |
Fri, 16 December 2005 22:41 |
ToFo
Messages: 219 Registered: May 2009
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Master |
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if it's just rising response from the collapsing directivity of the large driver then you are right on. you can set the crossover electrically lower than your real acoustic target. You will not get an ideal summation of the two drivers, but you can take steps to insure you don't cancel out either (or just hook the tweeter up in and out of phase and see which is louder at your crossover frequency, and hope for the best). A calculated second best is not necesarily a bad thing. Cone breakup resonances are another matter altogether. I believe all the big drivers have some past 800 Hz or thereabouts, so it's more a matter of how bad are they and which sound least offensive. There can be a lot of sound still coming off the cone after the event is over because the cone is ringing like a bell at certain frequencies. You can cross it over or EQ it all you want, but it can still quack like a duck if the driver is spikey up high. I heard a frat party system once that had a hot 18 crossed to a small 3500 hz horn. Didn't matter what the instrument was, handclap - quack!, Snare - Quack!!, saxophone - QUACCKKK!!, you get my drift. Most frequency plots are set so the "pen" moves too slow to show how bad breakup really is, so you just have to be a carefull shopper and find designers/posters you trust (guess your in the right place already). Thomas
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