Crossover Question

ppfred · 9th May 2006, 04:33 AM

Hi guys,
I need some guidance in my first crossover design.
It seems that the electrical crossover will combine with the natural frequency drop-off of a driver.
I have a tweeter that begins what looks like a -10 dB/octave slope at 1600Hz. I would like to crossover at 2500Hz. Where does the combining effect take place? If I use a 2nd order Xover does the frequency begin to drop-off at a rate of 22 dB/octave immediately at 2500Hz or would this only occur if I crossed over at 1600Hz?

Thanx,
fred p

ostie01 · 9th May 2006, 06:31 AM

Hi, with a 2nd order crossover the slope will be 12dB/octave at 2500Hz. 1st order=6dB , 2nd order= 12dB , 3rd order=18dB and 4th order=24dB/octave

ppfred · 9th May 2006, 01:46 PM

Thanx Ostie.

But the question remains - at what frequency does the driver's natural drop-off rate & the electrical (crossover) rate combine to give a steeper slope.

fred p

sreten · 10th May 2006, 09:16 AM

Hi,

if you crossover over first order at 3Khz, then you have an overdamped 3rd order acoustic alignment.
(ignoring the capacitors interaction with the tweeters resonant impedance peak)

Around 3kHz the alignment is ~ first order, but below 1.5kHz the roll-off is 3rd order.

http://www.zaphaudio.com/ Have a good rummage around this site.

/sreten.

9th May 2006, 04:33 AM	#1
ppfred diyAudio Member Join Date: Jan 2002 Location: Montreal	Crossover Question Hi guys, I need some guidance in my first crossover design. It seems that the electrical crossover will combine with the natural frequency drop-off of a driver. I have a tweeter that begins what looks like a -10 dB/octave slope at 1600Hz. I would like to crossover at 2500Hz. Where does the combining effect take place? If I use a 2nd order Xover does the frequency begin to drop-off at a rate of 22 dB/octave immediately at 2500Hz or would this only occur if I crossed over at 1600Hz? Thanx, fred p __________________ Believe nothing you read and only half of what you see.

9th May 2006, 01:46 PM	#3
ppfred diyAudio Member Join Date: Jan 2002 Location: Montreal	Thanx Ostie. But the question remains - at what frequency does the driver's natural drop-off rate & the electrical (crossover) rate combine to give a steeper slope. fred p __________________ Believe nothing you read and only half of what you see.

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9th May 2006, 06:31 AM	#2
ostie01 diyAudio Member Join Date: Mar 2005 Location: quebec	Hi, with a 2nd order crossover the slope will be 12dB/octave at 2500Hz. 1st order=6dB , 2nd order= 12dB , 3rd order=18dB and 4th order=24dB/octave

10th May 2006, 09:16 AM	#4
sreten diyAudio Member Join Date: Nov 2003 Location: Brighton UK	Hi, if you crossover over first order at 3Khz, then you have an overdamped 3rd order acoustic alignment. (ignoring the capacitors interaction with the tweeters resonant impedance peak) Around 3kHz the alignment is ~ first order, but below 1.5kHz the roll-off is 3rd order. http://www.zaphaudio.com/ Have a good rummage around this site. /sreten.

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