active X-over

keyser · 17th January 2005, 05:04 PM

hi guys!

i'd like to bi-amp my 3-way speakers. to do it properly, i need an active crossover. The passive crossover crosses at 300, and 3500 hertz. It is my intention to use an active crossover at 300 hertz, and keep the passive one at 3500 hertz.
does anyone of you have experience with a variable crossover as used in the world of PA? Is it a bad thing that the passive crossover in my speakers is of a 4th- or 3th-order, and that most active crossovers are 1st-order?
any help would be appreciated!

keyser

blu_line · 18th January 2005, 06:03 AM

http://sound.westhost.com/project09.htm

grtz

Simon

Bill Fitzpatrick · 18th January 2005, 07:17 AM

Quote:

Originally posted by keyser
Is it a bad thing that the passive crossover in my speakers is of a 4th- or 3th-order, and that most active crossovers are 1st-order?
any help would be appreciated!

Most active crossovers are 2nd, 3rd or 4th order, not 1st.

The project that blu_line recommended would be excellent for your use at 300Hz.

keyser · 18th January 2005, 01:50 PM

Quote:

Originally posted by Bill Fitzpatrick

Most active crossovers are 2nd, 3rd or 4th order, not 1st.

The project that blu_line recommended would be excellent for your use at 300Hz.

oops....
I thought about that the other way around (first order being 24db, 4th order being 6 db)

the project blu_line suggested is of a 4th order design (Yes... 24 db)

De crossover in my speakers is probably of a lower order. Would using a 4th order filter where the manufacturer of the speaker chose for a lower order filter?

Bill Fitzpatrick · 18th January 2005, 06:11 PM

I jumped the gun on my recommendation.

The mfg. might have chosen a lower order because it was cheaper or they might have done some response tailoring with the passive network.

The problem with trying to replace a passive with an active is that usually you do not have enough information about what the passive is doing, particularly with the mid to tweet cross.

For the woof to mid it's less of a problem. One concern is the phase. If the mfg. used 2nd highpass and 2nd lowpass they probably reversed the phase of one of the drivers. With a 4th order you would have to maintain same polarity.

To go further and be correct you should have a schematic of the woof/mid crossover and parts values along with, at least, the DC resistance of the drivers.

Given the relatively low cost of the parts to built the active crossover proposed you might want to give it a shot, especially if you could use it elsewhere or sell it if things didn't work out.

keyser · 18th January 2005, 07:43 PM

thanks for the input, Bill.
I guess what you're saying is that a 4th-order filter would be okay, but that i need more info about the original passive x-over to know how to connect and set it all up.
would a picture of the x-over tell you enough about it to know what type it is? Are there things I could look at myself?

Bill Fitzpatrick · 18th January 2005, 07:56 PM

You couldn't draw a schematic of it?

keyser · 20th January 2005, 03:09 PM

I've had a look at my speakers, and saw that all screws have *hats. (are those called torque?) I don't yet have tools to open them. have to get those first, then i'll have a look at the filter.
btw. I've bought an active X-over through e-bay yesterday.
It's a Behringer cx2310.

keyser · 20th January 2005, 03:26 PM

Just saw that the behringer features a phase reverse-switch for every channel and between low- and high. Do I still need to know whether the manufacturer reversed the phase or not?
for more info on the behringer:

http://www.behringer.com/CX2310/index.cfm?lang=ENG

Jan Dupont · 20th January 2005, 08:32 PM

Just to give you an idea for a diy solution http://www.delta-audio.com/Active%20filter%20one.htm

17th January 2005, 05:04 PM	#1
keyser diyAudio Member Join Date: Oct 2004 Location: The Netherlands	active X-over hi guys! i'd like to bi-amp my 3-way speakers. to do it properly, i need an active crossover. The passive crossover crosses at 300, and 3500 hertz. It is my intention to use an active crossover at 300 hertz, and keep the passive one at 3500 hertz. does anyone of you have experience with a variable crossover as used in the world of PA? Is it a bad thing that the passive crossover in my speakers is of a 4th- or 3th-order, and that most active crossovers are 1st-order? any help would be appreciated! keyser

20th January 2005, 08:32 PM	#10
Jan Dupont diyAudio Member Join Date: Apr 2003 Location: Copenhagen, Denmark	Just to give you an idea for a diy solution http://www.delta-audio.com/Active%20filter%20one.htm __________________ Free Schematic and Service Manual downloads www.audio-circuit.dk, Company: www.dupont-audio.com, Joint venture: www.DupontMantra.com

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18th January 2005, 06:03 AM	#2
blu_line diyAudio Member Join Date: Jan 2002 Location: The Netherlands	http://sound.westhost.com/project09.htm grtz Simon

18th January 2005, 06:11 PM	#5
Bill Fitzpatrick diyAudio Member Join Date: Jun 2001 Location: Eugene, OR	I jumped the gun on my recommendation. The mfg. might have chosen a lower order because it was cheaper or they might have done some response tailoring with the passive network. The problem with trying to replace a passive with an active is that usually you do not have enough information about what the passive is doing, particularly with the mid to tweet cross. For the woof to mid it's less of a problem. One concern is the phase. If the mfg. used 2nd highpass and 2nd lowpass they probably reversed the phase of one of the drivers. With a 4th order you would have to maintain same polarity. To go further and be correct you should have a schematic of the woof/mid crossover and parts values along with, at least, the DC resistance of the drivers. Given the relatively low cost of the parts to built the active crossover proposed you might want to give it a shot, especially if you could use it elsewhere or sell it if things didn't work out.

18th January 2005, 07:43 PM	#6
keyser diyAudio Member Join Date: Oct 2004 Location: The Netherlands	thanks for the input, Bill. I guess what you're saying is that a 4th-order filter would be okay, but that i need more info about the original passive x-over to know how to connect and set it all up. would a picture of the x-over tell you enough about it to know what type it is? Are there things I could look at myself?

18th January 2005, 07:56 PM	#7
Bill Fitzpatrick diyAudio Member Join Date: Jun 2001 Location: Eugene, OR	You couldn't draw a schematic of it?

20th January 2005, 03:09 PM	#8
keyser diyAudio Member Join Date: Oct 2004 Location: The Netherlands	I've had a look at my speakers, and saw that all screws have *hats. (are those called torque?) I don't yet have tools to open them. have to get those first, then i'll have a look at the filter. btw. I've bought an active X-over through e-bay yesterday. It's a Behringer cx2310.

20th January 2005, 03:26 PM	#9
keyser diyAudio Member Join Date: Oct 2004 Location: The Netherlands	Just saw that the behringer features a phase reverse-switch for every channel and between low- and high. Do I still need to know whether the manufacturer reversed the phase or not? for more info on the behringer: http://www.behringer.com/CX2310/index.cfm?lang=ENG

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