active corssover, 2 - 3 way or something else?

matjans · 26th April 2004, 01:08 AM

hey guys,

i'm currently working on an active xover to drive my old b&w 220's actively. Problem is that they are sort of 2.5 way speakers.

First xover is 24dB @ 3kHz, second is 6db @ 1kHz. What should i do?

Should i just build a 2 way linkwitz @ 3kHz and let the speaker's internal (crappy) passive filter do the rest? Sort of defeats the point of biamping since the crossover point is fairly high.

Or should I build a mixture of active/passive filters; a linkwitz 24db @ 3khz + a passive line level xover for the bass?

Or do you guys think it would be wise to ignore all b&w's research and implement a (fairly standard) 3kHz / 300 Hz 3 way active linkwitz?

The number of amplifiers is not important, i've got 4 diy stereo amps laying around so...

Any hints/tips are welcome.

jackinnj · 26th April 2004, 01:50 AM

op amps are cheap.

one thing to note -- when you cascade filters -- particularly in the Sallen Key topology -- component values become more critical. The TI filter tools allow you to input various precision grades of capacitors and resistors and look at the likelihood of the filter being on the mark.

you can also consider using an all-pass filter on the high or low to alter the phase --

kingdaddy · 26th April 2004, 03:53 PM

The Marchand XM-44 will do asymmetric slopes and anything else you want, a bit pricey though.

http://marchandelec.com/xm44.htm

matjans · 26th April 2004, 04:02 PM

omigod... that;s pretty expensive

just went out to get some components for a 24db @ 3000 hz / 12db @ 1000 Hz (second order in stead of a first order but still) and paid 28 euro's.

3 way linkwitz it will be !

Bill Fitzpatrick · 26th April 2004, 04:08 PM

Quote:

Originally posted by matjans

First xover is 24dB @ 3kHz, second is 6db @ 1kHz. What should i do?

Assuming that you can get away with replacing the 24db @ 3K filter - which is unlikely since there may have been an adjustment of values for response tailoring or impedance accomodation- going up to 12db on the 1K filter is going to mess things up pretty well.

matjans · 26th April 2004, 04:27 PM

i completely agree with the second part. We'll see.

strange thing is the configuration of the xover. first woofer gets everything below 3000hz (no highpass), second woofer has an additional lowpass filter at 1khz.

If it doesn't work i'll just have to build a pair of speakers to match my crossover

5th element · 26th April 2004, 06:00 PM

Its not strange at all, that is a 2.5 way. The top woofer covering the whole range up to lowpass and then the 2nd woofer filling in for baffle step loss.

matjans · 26th April 2004, 06:58 PM

ah ok, didn't get that, obviously.

this, of course, also means that a 12 db filter is completely out of the question. 6db it will be then.

5th element · 26th April 2004, 09:46 PM

Yup usually 1st order added on .5 speaker

planet10 · 27th April 2004, 06:45 AM

Quote:

Originally posted by matjans
Or should I build a mixture of active/passive filters; a linkwitz 24db @ 3khz + a passive line level xover for the bass?

With 3 amps... amps on the bottom should be identical...

1 kHz for the 0.5 driver seems high (ie a baffle ~5" wide)... i'd set that one up so that you can play with it.

dave

26th April 2004, 01:08 AM	#1
matjans diyAudio Member Join Date: Aug 2003 Location: Utrecht, NL	active corssover, 2 - 3 way or something else? hey guys, i'm currently working on an active xover to drive my old b&w 220's actively. Problem is that they are sort of 2.5 way speakers. First xover is 24dB @ 3kHz, second is 6db @ 1kHz. What should i do? Should i just build a 2 way linkwitz @ 3kHz and let the speaker's internal (crappy) passive filter do the rest? Sort of defeats the point of biamping since the crossover point is fairly high. Or should I build a mixture of active/passive filters; a linkwitz 24db @ 3khz + a passive line level xover for the bass? Or do you guys think it would be wise to ignore all b&w's research and implement a (fairly standard) 3kHz / 300 Hz 3 way active linkwitz? The number of amplifiers is not important, i've got 4 diy stereo amps laying around so... Any hints/tips are welcome. __________________ Si fractum non sit, noli id reficere!

26th April 2004, 01:50 AM	#2
jackinnj diyAudio Member Join Date: Apr 2002 Location: Llanddewi Brefi, NJ	build a pair of 24dB op amps are cheap. one thing to note -- when you cascade filters -- particularly in the Sallen Key topology -- component values become more critical. The TI filter tools allow you to input various precision grades of capacitors and resistors and look at the likelihood of the filter being on the mark. you can also consider using an all-pass filter on the high or low to alter the phase --

26th April 2004, 04:02 PM	#4
matjans diyAudio Member Join Date: Aug 2003 Location: Utrecht, NL	omigod... that;s pretty expensive just went out to get some components for a 24db @ 3000 hz / 12db @ 1000 Hz (second order in stead of a first order but still) and paid 28 euro's. 3 way linkwitz it will be ! __________________ Si fractum non sit, noli id reficere!

26th April 2004, 04:27 PM	#6
matjans diyAudio Member Join Date: Aug 2003 Location: Utrecht, NL	i completely agree with the second part. We'll see. strange thing is the configuration of the xover. first woofer gets everything below 3000hz (no highpass), second woofer has an additional lowpass filter at 1khz. If it doesn't work i'll just have to build a pair of speakers to match my crossover __________________ Si fractum non sit, noli id reficere!

26th April 2004, 06:00 PM	#7
5th element diyAudio Member Join Date: Oct 2002 Location: England	Its not strange at all, that is a 2.5 way. The top woofer covering the whole range up to lowpass and then the 2nd woofer filling in for baffle step loss. __________________ What the hell are you screamin' for? Every five minutes there's a bomb or somethin'! I'm leavin! bzzzz! Droggon Attack!


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26th April 2004, 03:53 PM	#3
kingdaddy diyAudio Member Join Date: Mar 2002 Location: Fort Worth, Texas	The Marchand XM-44 will do asymmetric slopes and anything else you want, a bit pricey though. http://marchandelec.com/xm44.htm

26th April 2004, 06:58 PM	#8
matjans diyAudio Member Join Date: Aug 2003 Location: Utrecht, NL	ah ok, didn't get that, obviously. this, of course, also means that a 12 db filter is completely out of the question. 6db it will be then. __________________ Si fractum non sit, noli id reficere!

26th April 2004, 09:46 PM	#9
5th element diyAudio Member Join Date: Oct 2002 Location: England	Yup usually 1st order added on .5 speaker __________________ What the hell are you screamin' for? Every five minutes there's a bomb or somethin'! I'm leavin! bzzzz! Droggon Attack!

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