Need a cheap passive 100Hz crossover.

Boscoe · 09:35 PM

Basically using a butterworth design which uses the smallest capacitors it's still about 50uf and so quite expensive any other ideas? I think the impedence is around 8ohms (8-9 free air but I will be putting this in a horn), this is the minimum impedance of the driver anyway.

Thanks
Boscoe

Thawach · 22nd December 2010, 08:49 AM

Boscoe now i have the problem likes this. i sim xo passive sub. the cut off 150 hz. the coil is very lagre 8 mh . condenser is about 200 mf ! 200 mf i think will use the cheap C[electrolytic]. but only has the coil is very expensive. the cost of big coil make me think a lot. lol it's close to plate amp.

djk · 22nd December 2010, 09:00 AM

A 12dB Butterworth 100hz passive crossover requires a 140µF capacitor and an 18mH inductor for and 8 ohm driver.

Large wire gauge inductors are not cheap, nor are good capacitors that size. A 200W plate amplifier may only be a few dollars more.

I bought a used Crest CPX 900 for $200 (including freight). 320W/4R per channel, 600W/8R bridged, built in crossover.

Thawach · 22nd December 2010, 09:09 AM

djk i surprise the same as u, why 100 hz the C is 50 mf, i sim 150 hz. it's 200 mf . think that he calcultate mistake

tvrgeek · 22nd December 2010, 05:39 PM

Cheap, passive Sorry but that is an oxymoron. Big caps, big coils of fat wire.
Now, one can play games. One can change the input and feedback cap on an amp to make the amp itself a 12dB filter. Band pass boxes can do some filtering. Other games can be done in a receiver. Look at the problem from a systems view. Think out of the box. (sorry)

Boscoe · 22nd December 2010, 06:43 PM

Thats all good thanks folks I'm going to use an active design now.

jrenkin · 22nd December 2010, 07:03 PM

Line level XO?

Frank Berry · 22nd December 2010, 07:36 PM

I designed a line level low pass filter several years ago. This might give you some ideas.

Boscoe · 22nd December 2010, 08:26 PM

Quote:

Line level XO?

Yep!

Quote:

Originally Posted by Frank Berry

I designed a line level low pass filter several years ago. This might give you some ideas.

Can this not be done a lot more simply? With just one op-amp, a couple of resistors and capacitors?

jrenkin · 22nd December 2010, 08:33 PM

Quote:

Originally Posted by jrenkin

Line level XO?

I meant Passive line level XO, as long as you have a little extra amp power.

21st December 2010, 09:32 PM	#1
Boscoe diyAudio Member Join Date: Feb 2010 Location: England	Need a cheap passive 100Hz crossover. Basically using a butterworth design which uses the smallest capacitors it's still about 50uf and so quite expensive any other ideas? I think the impedence is around 8ohms (8-9 free air but I will be putting this in a horn), this is the minimum impedance of the driver anyway. Thanks Boscoe Last edited by Boscoe; 21st December 2010 at 09:35 PM.

22nd December 2010, 08:49 AM	#2
Thawach diyAudio Member Join Date: Dec 2007	Boscoe now i have the problem likes this. i sim xo passive sub. the cut off 150 hz. the coil is very lagre 8 mh . condenser is about 200 mf ! 200 mf i think will use the cheap C[electrolytic]. but only has the coil is very expensive. the cost of big coil make me think a lot. lol it's close to plate amp. __________________ out of the past=out of the future=in the present time+ing

22nd December 2010, 09:00 AM	#3
djk diyAudio Member Join Date: Feb 2001 Location: USA	A 12dB Butterworth 100hz passive crossover requires a 140µF capacitor and an 18mH inductor for and 8 ohm driver. Large wire gauge inductors are not cheap, nor are good capacitors that size. A 200W plate amplifier may only be a few dollars more. I bought a used Crest CPX 900 for $200 (including freight). 320W/4R per channel, 600W/8R bridged, built in crossover. __________________ Candidates for the Darwin Award should not read this author.

22nd December 2010, 09:09 AM	#4
Thawach diyAudio Member Join Date: Dec 2007	djk i surprise the same as u, why 100 hz the C is 50 mf, i sim 150 hz. it's 200 mf . think that he calcultate mistake __________________ out of the past=out of the future=in the present time+ing

Thread Tools	Search this Thread
Show Printable Version Email this Page	Search this Thread: Advanced Search


	Please consider donating to help us continue to serve you. Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving

22nd December 2010, 05:39 PM	#5
tvrgeek diyAudio Member Join Date: Dec 2009 Location: Md	Cheap, passive Sorry but that is an oxymoron. Big caps, big coils of fat wire. Now, one can play games. One can change the input and feedback cap on an amp to make the amp itself a 12dB filter. Band pass boxes can do some filtering. Other games can be done in a receiver. Look at the problem from a systems view. Think out of the box. (sorry)

22nd December 2010, 06:43 PM	#6
Boscoe diyAudio Member Join Date: Feb 2010 Location: England	Thats all good thanks folks I'm going to use an active design now.

22nd December 2010, 07:03 PM	#7
jrenkin diyAudio Member Join Date: Nov 2007 Location: Denver, Colorado	Line level XO?

Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
Passive 3 way crossover	hamedfazelm	Multi-Way	2	14th July 2010 01:53 AM
Passive crossover into active crossover	hahfran	Multi-Way	16	10th February 2008 06:16 PM
Passive Crossover for Passive Subwoofer?	Toast_Master	Subwoofers	23	30th April 2006 12:14 AM
Passive crossover	Twisted	Parts	0	19th January 2004 08:32 PM
About passive crossover	stefanobilliani	Pass Labs	5	2nd August 2002 07:39 PM

New To Site?	Need Help?
Register to Participate Search Privacy Statement Contact Us	Frequently Asked Questions Did you forget your password? Mark Forums Read