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Old 20th April 2003, 09:26 PM   #1
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Default Simple subwoofer cross-over

i want a simple circuit to take the two outputs from my power amplifier (60w max), add them (or whatever you want to call it) and give me an output for a subwoofer.

thanks in advance for any help.
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Old 20th April 2003, 09:39 PM   #2
audioPT is offline audioPT  Portugal
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http://sound.westhost.com/project84.htm
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Old 21st April 2003, 10:01 AM   #3
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there a bit complicated arnt they? i just want to add the outputs. i dont want any controls.
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Old 21st April 2003, 07:35 PM   #4
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Well,
In that case, and if you want a summing signal, just add 3 resistors and other amplifier.

at least 100k in each output of the main amplifier, join this 2 with another of 22k and then to ground.

you get the summing signal between the 2 extremes of the 22k resistor.

now, with this, you'll put into the subwoofer all the audio bandwidth. this signal is applyed to a third amplifier and...

some sound will get out of the sub.

more simple tan this, is impossible...

You can also put in parallel with the 22k resistor a 470nF cap to make a low pass filter.

I'd like to make a remark here:
This is the worst way to do this, but I'm answering to your question.

Another way is to buy a dual coil subwoofer and make a good low pass filter.

Pedro Martins
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Old 23rd April 2003, 09:56 PM   #5
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Quote:
Originally posted by audioPT
Well,
In that case, and if you want a summing signal, just add 3 resistors and other amplifier.

at least 100k in each output of the main amplifier, join this 2 with another of 22k and then to ground.

you get the summing signal between the 2 extremes of the 22k resistor.

now, with this, you'll put into the subwoofer all the audio bandwidth. this signal is applyed to a third amplifier and...

some sound will get out of the sub.

more simple tan this, is impossible...

You can also put in parallel with the 22k resistor a 470nF cap to make a low pass filter.

I'd like to make a remark here:
This is the worst way to do this, but I'm answering to your question.

Another way is to buy a dual coil subwoofer and make a good low pass filter.

Pedro Martins

like this?
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File Type: gif sub xo.gif (1.8 KB, 403 views)
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Old 23rd April 2003, 10:34 PM   #6
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Default just made this ...

built this about 2 days ago and works perfectly. -3db is 70hz for subwoofer bass. i used 741s just as testing but better op amps should be chosen. the 3.9ohm load represents the speaker.

Click the image to open in full size.

-chris
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Old 27th April 2003, 10:05 PM   #7
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like this?
Attached Images
File Type: gif sub xo.gif (1.8 KB, 305 views)
__________________
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Old 28th April 2003, 08:38 PM   #8
audioPT is offline audioPT  Portugal
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Hi Matttcattt


Just do like yhis:
(Beware that this isn't the best way)
To get better results, go active!

Pedro Martins
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File Type: jpg subxover.jpg (13.6 KB, 291 views)
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Old 28th April 2003, 10:45 PM   #9
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thanks, where can i find a simple low pass filter as well? what would a suitable value for the low pass filter be? 100Hz?
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Old 30th April 2003, 03:44 PM   #10
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Quote:
Originally posted by audioPT
Hi Matttcattt


Just do like yhis:
(Beware that this isn't the best way)
To get better results, go active!

Pedro Martins
is the 1uf capacitor the low pass filter or do i add a 470nf as well? or do i use a 470nf one instead of the 1uf?

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