Low audio frequency cutoff filter

[Josetcr]

Can any body suggest me a passive filter circuit to cut frequency below 200 hertz.

[janneman]

Originally Posted by Josetcr

Can any body suggest me a passive filter circuit to cut frequency below 200 hertz.

Depends a bit on your situation. If you want to build it into your power amp, you can probably get by just be changing a capacitor.
Also important is what you feed it with - the output impedance of your source can have influence on the cut frequency.
How steep do you want it to be - come to think of it, why do you want it; what's the problem you are trying to solve?

jan didden

[Josetcr]

i had setup a custom 5.1 channel surround amplifier system
the filter i need is for 5 surround channel amplifier using tda2030a 12v dual supply (left,right,rear left,rear right and center channel) 3inch 4 ohms 10 watts speakers as load
input source is from pc sound card
i want to build it into my power amp actualy a passive filter at input of amplifier which cuts or bypasses low frequencies (below 200 or 250 hertz)
input signal coupling capacitor used for amplifiers is 2.2 mfd electrolyte capacitor
low frequencies causes distortion in my speakers

[janneman]

Originally Posted by Josetcr

i had setup a custom 5.1 channel surround amplifier system
the filter i need is for 5 surround channel amplifier using tda2030a 12v dual supply (left,right,rear left,rear right and center channel) 3inch 4 ohms 10 watts speakers as load
input source is from pc sound card
i want to build it into my power amp actualy a passive filter at input of amplifier which cuts or bypasses low frequencies (below 200 or 250 hertz)
input signal coupling capacitor used for amplifiers is 2.2 mfd electrolyte capacitor
low frequencies causes distortion in my speakers

Do you know the input resistance of your amp? Then you could just replace the 2.2uF (I assume it is uF not mF) and do it that way.

Example: 10k input R, C=1/(2*pi*200Hz*10k) ~ 1/12 uF, or, say, 75nF.
But you'd lose a lot of LF information; maybe the speakers distort because they are not suited to full range? A 3inch that is supposed to go all the way down is probably not a good choice here.

jan didden

[Josetcr]

input coupling capacitor is 2.2uF
i don't know the input resistance may be 22k i will check it
i am ok with the Lf info lose.(5.1 i build is a low budget one, speakers are also not that good that's y i want to cut Low frequencies) got a better sub-woofer system


Thank You

[Josetcr]

i think replacing 2.2uF will be a good idea

thank you for the information

[Hitec]

No problem if you want to build a passive one but I think active is usually better if it can be used (i.e. the signal is low-level / low-power). It can be made steeper and of lighter and cheaper components. I have designed one high-pass filter using this project as a basis. I simulated it but haven't yet tested though

[Josetcr]

thanks