passive crossovers....

stuman · 20th August 2007, 04:05 PM

on payday this month i will be buying a subwoofer for my bedroom audio, the problem is the small speakers that i use are in full range at the moment and when i put the subwoofer in would like to have a bass pass filter on them at about 50hz where they start to drop off naturally so that when pushed to high SPL's i dont get the port chuffing noises, i could always bung the bassport on the back but not sure weather the response curve would be as good as it is with.

so what im basically asking is are there any good designs out there for a passive 50hz bass filter?

Cal Weldon · 20th August 2007, 04:15 PM

A 50 Hz passive XO will be very expensive. Consider using an active filter. In fact, you can often buy a plate amp with a built in XO for little more than the components needed for a passive 50 Hz.

Lumba Ogir · 21st August 2007, 01:10 AM

Hi,
I would just place a capacitor at the input of the poweramp

planet10 · 21st August 2007, 06:51 AM

Quote:

Originally posted by Lumba Ogir
Hi,
I would just place a capacitor at the input of the poweramp

This is the way to go. Here is a web page that will help you figure out how big the cap needs to be (ise the input impedance of your amp as R2 in the 1st order high pass filter.

http://t-linespeakers.org/tech/filters/passiveHLxo.html

dave

bastek · 21st August 2007, 08:25 AM

I use a 150microF electrolytic in series with the woofer input on the speaker. If your speaker only has 2 posts, you can add a 10microF polypropylene cap in parallel. My 2 way bookself has a 5.25" mid-woofer.

planet10 · 21st August 2007, 09:27 AM

Quote:

Originally posted by bastek
I use a 150microF electrolytic in series with the woofer input on the speaker. If your speaker only has 2 posts, you can add a 10microF polypropylene cap in parallel. My 2 way bookself has a 5.25" mid-woofer.

An elco after the amp will not sound anywhere near as good as a poly before the amp... also to get his desired 50 Hz he'd need 400 uF if the speaker was a flat 8 ohms, but a speaker near its cut off is far from flat.

dave

stuman · 21st August 2007, 02:00 PM

sorry, i should have posted some more info.

the sound is going to be sent to my amp which has a dedicated line out for subwoofer which i am planning on using thats all fine however i would like to filter the the speakers on from the standard binding posts and was wandering about decent crossovers? i can spend about £200 for the pair? any ideas?

planet10 · 21st August 2007, 05:31 PM

Quote:

Originally posted by stuman
the sound is going to be sent to my amp which has a dedicated line out for subwoofer which i am planning on using thats all fine however i would like to filter the the speakers on from the standard binding posts and was wandering about decent crossovers? i can spend about £200 for the pair? any ideas?

What kind of speaker are your satelittes.

A passive XO on any speaker this low and this close to its cutoff is a nightmare and will likely be a waste of effort. You can't get at the power amp separately?

dave

matthew c · 22nd August 2007, 10:11 PM

sorry to take the poster over put i cant post in the main room

phreeky82 · 22nd August 2007, 10:34 PM

So you just wanna high-pass the satellites using a passive x-over? Wouldn't the amp/system be doing this for you actively? If not (odd), you could just try a cap in series with the satellites but it may not be steep enough depending on the x-over freq.

As stated, a passive x-over at such a low freq is a pain in the a*se (but at least its a high-pass and not a low-pass!!!).

20th August 2007, 04:05 PM	#1
stuman diyAudio Member Join Date: Nov 2004 Location: Fareham	passive crossovers.... on payday this month i will be buying a subwoofer for my bedroom audio, the problem is the small speakers that i use are in full range at the moment and when i put the subwoofer in would like to have a bass pass filter on them at about 50hz where they start to drop off naturally so that when pushed to high SPL's i dont get the port chuffing noises, i could always bung the bassport on the back but not sure weather the response curve would be as good as it is with. so what im basically asking is are there any good designs out there for a passive 50hz bass filter?

20th August 2007, 04:15 PM	#2
Cal Weldon Speakerholic diyAudio Moderator Join Date: Jan 2004 Location: British Columbia	A 50 Hz passive XO will be very expensive. Consider using an active filter. In fact, you can often buy a plate amp with a built in XO for little more than the components needed for a passive 50 Hz. __________________ Next stop: Margaritaville Some of Cal's stuff \| Cal Weldon Consulting

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21st August 2007, 01:10 AM	#3
Lumba Ogir Banned Join Date: Apr 2005 Location: Stockholm	Hi, I would just place a capacitor at the input of the poweramp

21st August 2007, 08:25 AM	#5
bastek diyAudio Member Join Date: Dec 2005 Location: NY	I use a 150microF electrolytic in series with the woofer input on the speaker. If your speaker only has 2 posts, you can add a 10microF polypropylene cap in parallel. My 2 way bookself has a 5.25" mid-woofer.

21st August 2007, 02:00 PM	#7
stuman diyAudio Member Join Date: Nov 2004 Location: Fareham	sorry, i should have posted some more info. the sound is going to be sent to my amp which has a dedicated line out for subwoofer which i am planning on using thats all fine however i would like to filter the the speakers on from the standard binding posts and was wandering about decent crossovers? i can spend about £200 for the pair? any ideas?

22nd August 2007, 10:11 PM	#9
matthew c diyAudio Member Join Date: Aug 2007	sorry to take the poster over put i cant post in the main room

22nd August 2007, 10:34 PM	#10
phreeky82 diyAudio Member Join Date: May 2003 Location: Townsville, Australia	So you just wanna high-pass the satellites using a passive x-over? Wouldn't the amp/system be doing this for you actively? If not (odd), you could just try a cap in series with the satellites but it may not be steep enough depending on the x-over freq. As stated, a passive x-over at such a low freq is a pain in the a*se (but at least its a high-pass and not a low-pass!!!).

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