Low pass audio filter - Electronic Circuits Projects Diagrams Free

steven_first_2001 · 9th January 2005, 02:15 PM

Hey guys, I need some help making a low pass audio filter. I have been trying to build one in shop but just can’t get it right. I need a filter that will cut out at about 200 Hz and up but all of my filters suck. I have been trying to make a passive low pass filter that would be hooked up to the inputs of a 1200W car amp that has no audio filters (boosts all audio freq.) It’s not for me. I told a kid that I would see what I could do because he spent a lot on this amp and he is only interested in bass (what a surprise). It was thinking of going over to a active filter but I am worried he will overdrive the IC to much. I have been messing with this for half of the school year and still have nothing yet. If someone can just make a schematic active or passive I would really appreciate it. Thanks

**Nigel Goodwin** · 9th January 2005, 04:08 PM

Quote:

Originally Posted by steven_first_2001

Hey guys, I need some help making a low pass audio filter. I have been trying to build one in shop but just can’t get it right. I need a filter that will cut out at about 200 Hz and up but all of my filters suck. I have been trying to make a passive low pass filter that would be hooked up to the inputs of a 1200W car amp that has no audio filters (boosts all audio freq.) It’s not for me. I told a kid that I would see what I could do because he spent a lot on this amp and he is only interested in bass (what a surprise). It was thinking of going over to a active filter but I am worried he will overdrive the IC to much. I have been messing with this for half of the school year and still have nothing yet. If someone can just make a schematic active or passive I would really appreciate it. Thanks

There are LOAD'S of filter designs on the net, a simple google will find more than you could ever need.

Try http://sound.westhost.com/projects-3.htm for some filter designs, and for information (on the rest of the site) about filters and sub-woofers.

Russlk · 10th January 2005, 12:30 AM

Here is a passive filter. You have to use the parts specified to get the response shown. I assume the source is a low impedance and the load is high impedance.

steven_first_2001 · 10th January 2005, 10:47 AM

There are many filters out on the internet but none of the ones I have found have given part values. They want you to use the equasion to figure it out, I just want to build one that is already been built.

I will check my impedence loads for the filter app. today to make shure they are what you made this thing for. I asume that the doted line is the filter under a load right?

Russlk · 10th January 2005, 04:32 PM

The dotted line is the phase angle, the scale is on the right. The source resistance should be less than 100 ohms. If the load resistance is less than 100K, leave the 10K resistor out. If the load resistance is less than 10K, there will be some attenuation of the signal.

steven_first_2001 · 23rd January 2005, 06:35 PM

I just built the filter in school and it rocks! thanks man!

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9th January 2005, 02:15 PM	(permalink)
steven_first_2001	Low pass audio filter Hey guys, I need some help making a low pass audio filter. I have been trying to build one in shop but just can’t get it right. I need a filter that will cut out at about 200 Hz and up but all of my filters suck. I have been trying to make a passive low pass filter that would be hooked up to the inputs of a 1200W car amp that has no audio filters (boosts all audio freq.) It’s not for me. I told a kid that I would see what I could do because he spent a lot on this amp and he is only interested in bass (what a surprise). It was thinking of going over to a active filter but I am worried he will overdrive the IC to much. I have been messing with this for half of the school year and still have nothing yet. If someone can just make a schematic active or passive I would really appreciate it. Thanks

10th January 2005, 10:47 AM	(permalink)
steven_first_2001	There are many filters out on the internet but none of the ones I have found have given part values. They want you to use the equasion to figure it out, I just want to build one that is already been built. I will check my impedence loads for the filter app. today to make shure they are what you made this thing for. I asume that the doted line is the filter under a load right?

10th January 2005, 04:32 PM	(permalink)
Russlk	The dotted line is the phase angle, the scale is on the right. The source resistance should be less than 100 ohms. If the load resistance is less than 100K, leave the 10K resistor out. If the load resistance is less than 10K, there will be some attenuation of the signal. __________________ see my website: www.geocities.com/russlk

23rd January 2005, 06:35 PM	(permalink)
steven_first_2001	I just built the filter in school and it rocks! thanks man!