best way to make 8th order x-over?

Chester01 · May 10, 2006, 11:10 PM

hi, I am trying to create a crossover for my subwoofer, the sub is being run through a fullchannel amp making it necessary to use a very sharp slope on my crossover. I was wondering, if i use three 4th order crossovers (one 4th order to originally crossover, and then run the lowpass through a second x-over and the highpass through a second x-over) to maintain signal integrity would it be best to re-mix the low signal off of the second highpass crossover (signal that would be 'lost') and the high signal off the second lowpass crossover with the secondary highpass? would it be better just to loose this signal? Is it possible to just MAKE an 8th order x-over? how hard would this be? I looked at the source and couldnt follow it very well. Thanks for any info!

ROBSCIX · May 10, 2006, 11:20 PM

Wouldn't you just use a low pass, so everything below the crossover goes to the subwoofer? I know there are alot of different ways to do things with filters so maybe I don't understand it correctly..

Chester01 · May 10, 2006, 11:28 PM

well a crossover is basically a lowpass and highpass... afaik

ROBSCIX · May 10, 2006, 11:38 PM

Yeah, depends on how you look at it, I guess you could say a notch filter is a lowpass and a high pass etc..I just don't understand what you mean by X order crossover, can you explain that? just for my info..

Chester01 · May 11, 2006, 12:53 AM

the order is related to the -db/octave you get with the filter... for instance, an octave is a doubbling or halving of a frequency, lets say we x-over at 80 hz. crossovers dont CUT the frequency, they gradually roll off. if you are looking at the output on the high frequency side of the crossover, with a first order filter, at 160 hz, the signal will be -6db quieter than reference. second order would be -12 db, 4th order is -24db, 8th order is -48db. you an play around with this by loading 4th order crossver, frequency generator and a peak filter. connect the wavegen output to the crossover (in1). then put the low1 and high1 outputs to the inputs on the peak plugin. if you set the x-over at 1000 hz, look at the peak meeter, with the wavegen outputing 1000hz, both outputs (high and low) will be at the same level. if you set the wavegen to produce 500 hz, there will be a 24 db difference between the outputs on the peak plugin. if its at 2000 hz, the same will happen however the peak readings will 'swap'. if you halve the frequency or doubble it again, there will be a 48db difference

this is with a 4th order crossover remember. with an 8th order, it 'cuts' faster, each octave will be -48 db instead of -24 db.

Tril · May 11, 2006, 02:24 AM

If you want to understand the plugin called "4th order crossover", take a look at the files :
Cross_4th.cpp
Cross_4th.h
da_Crossover_4th.cpp

The plugin is a C++ plugin. You need to write the dane code and the c++ code and compile the c++ part of the plugin.

Chester01 · May 11, 2006, 04:19 AM

I understand that cross_4th.cpp and cross_4th.h are related to the GUI, and that da_crossover_4th.cpp is the dsp code... is the DSP code basically a matrix that the sound is running through? by the way, thanks for your help Tril!

BURRometer · Jun 10, 2006, 04:16 AM

I've constructed a few different "8th order" crossovers with the kx drivers providing positive results. Using the 4th order x-over followed by a notch filter or two will create the effect you're after. I suggest running you crossover output into an asio port and use an rta plugin to see the effects of the notch location and q. Once you acheive what you're after reroute the output.

May 10, 2006, 11:10 PM	#1
Chester01 HardwareHeaven Senior Member Join Date: Jan 2004 Location: St. Cloud, MN Posts: 492 Rep Power: 0	best way to make 8th order x-over? hi, I am trying to create a crossover for my subwoofer, the sub is being run through a fullchannel amp making it necessary to use a very sharp slope on my crossover. I was wondering, if i use three 4th order crossovers (one 4th order to originally crossover, and then run the lowpass through a second x-over and the highpass through a second x-over) to maintain signal integrity would it be best to re-mix the low signal off of the second highpass crossover (signal that would be 'lost') and the high signal off the second lowpass crossover with the secondary highpass? would it be better just to loose this signal? Is it possible to just MAKE an 8th order x-over? how hard would this be? I looked at the source and couldnt follow it very well. Thanks for any info! __________________ COMP: Dual Intel PIII 733 Mhz; GeForce 4 Ti 4600; 1.128 Gb RAM; SB0350 (Audigy 2 ZS Platnium) STEREO(I UPGRADED):Crown Audio K1 and K2 amplifiers (4000 watts at .1% THD ), JL 13w7 Subwoofer (6.5 CF) (2) 18" PR's, Klipsch SB-1's, some cement blocks for speaker stands...

May 10, 2006, 11:28 PM	Thread Starter #3
Chester01 HardwareHeaven Senior Member Join Date: Jan 2004 Location: St. Cloud, MN Posts: 492 Rep Power: 0	well a crossover is basically a lowpass and highpass... afaik __________________ COMP: Dual Intel PIII 733 Mhz; GeForce 4 Ti 4600; 1.128 Gb RAM; SB0350 (Audigy 2 ZS Platnium) STEREO(I UPGRADED):Crown Audio K1 and K2 amplifiers (4000 watts at .1% THD ), JL 13w7 Subwoofer (6.5 CF) (2) 18" PR's, Klipsch SB-1's, some cement blocks for speaker stands...

May 11, 2006, 12:53 AM	Thread Starter #5
Chester01 HardwareHeaven Senior Member Join Date: Jan 2004 Location: St. Cloud, MN Posts: 492 Rep Power: 0	the order is related to the -db/octave you get with the filter... for instance, an octave is a doubbling or halving of a frequency, lets say we x-over at 80 hz. crossovers dont CUT the frequency, they gradually roll off. if you are looking at the output on the high frequency side of the crossover, with a first order filter, at 160 hz, the signal will be -6db quieter than reference. second order would be -12 db, 4th order is -24db, 8th order is -48db. you an play around with this by loading 4th order crossver, frequency generator and a peak filter. connect the wavegen output to the crossover (in1). then put the low1 and high1 outputs to the inputs on the peak plugin. if you set the x-over at 1000 hz, look at the peak meeter, with the wavegen outputing 1000hz, both outputs (high and low) will be at the same level. if you set the wavegen to produce 500 hz, there will be a 24 db difference between the outputs on the peak plugin. if its at 2000 hz, the same will happen however the peak readings will 'swap'. if you halve the frequency or doubble it again, there will be a 48db difference this is with a 4th order crossover remember. with an 8th order, it 'cuts' faster, each octave will be -48 db instead of -24 db. __________________ COMP: Dual Intel PIII 733 Mhz; GeForce 4 Ti 4600; 1.128 Gb RAM; SB0350 (Audigy 2 ZS Platnium) STEREO(I UPGRADED):Crown Audio K1 and K2 amplifiers (4000 watts at .1% THD ), JL 13w7 Subwoofer (6.5 CF) (2) 18" PR's, Klipsch SB-1's, some cement blocks for speaker stands...

May 11, 2006, 04:19 AM	Thread Starter #7
Chester01 HardwareHeaven Senior Member Join Date: Jan 2004 Location: St. Cloud, MN Posts: 492 Rep Power: 0	I understand that cross_4th.cpp and cross_4th.h are related to the GUI, and that da_crossover_4th.cpp is the dsp code... is the DSP code basically a matrix that the sound is running through? by the way, thanks for your help Tril! __________________ COMP: Dual Intel PIII 733 Mhz; GeForce 4 Ti 4600; 1.128 Gb RAM; SB0350 (Audigy 2 ZS Platnium) STEREO(I UPGRADED):Crown Audio K1 and K2 amplifiers (4000 watts at .1% THD ), JL 13w7 Subwoofer (6.5 CF) (2) 18" PR's, Klipsch SB-1's, some cement blocks for speaker stands...

May 10, 2006, 11:20 PM	#2
ROBSCIX DriverHeaven Senior Member Join Date: Mar 2004 Posts: 1,732 Rep Power: 0	Wouldn't you just use a low pass, so everything below the crossover goes to the subwoofer? I know there are alot of different ways to do things with filters so maybe I don't understand it correctly..

May 10, 2006, 11:38 PM	#4
ROBSCIX DriverHeaven Senior Member Join Date: Mar 2004 Posts: 1,732 Rep Power: 0	Yeah, depends on how you look at it, I guess you could say a notch filter is a lowpass and a high pass etc..I just don't understand what you mean by X order crossover, can you explain that? just for my info..

May 11, 2006, 02:24 AM	#6
Tril S-3D enthusiast Join Date: Sep 2004 Location: Canada Posts: 1,676 Rep Power: 64 System Specs	If you want to understand the plugin called "4th order crossover", take a look at the files : Cross_4th.cpp Cross_4th.h da_Crossover_4th.cpp The plugin is a C++ plugin. You need to write the dane code and the c++ code and compile the c++ part of the plugin.

Jun 10, 2006, 04:16 AM	#8
BURRometer DriverHeaven Newbie Join Date: May 2006 Posts: 1 Rep Power: 0	I've constructed a few different "8th order" crossovers with the kx drivers providing positive results. Using the 4th order x-over followed by a notch filter or two will create the effect you're after. I suggest running you crossover output into an asio port and use an rta plugin to see the effects of the notch location and q. Once you acheive what you're after reroute the output.