How to make a low pass fillter in an amplifier?

Question

I'm now want to design an amplifier which is 2.1 channel.
Now my problem is to design the low pass fillter for the woofer.
Then i have to limit the frequency at the level of 300Hz is it too low to produce a best quality of bass?
To make this type of filter should it use a Op Am?

Answer 1

an OpAmp will give you an active filter, that is it can magnify the lower frequencies. Witout opamp you only can reduce the magnitude .

Answer 2

If I look at the diagram on http://en.wikipedia.org/wiki/Low-pass_filter as suggested by then I would rather use a yoke instead of a resistor.
Why?
Because - as rightly says, a passive filter is supposed to "kill" the high frequencies and only let the low ones through. But a resistor would first reduce the amplitude of both, hi and low, and then the capacitor gives the high frequencies the rest.
A yoke only kills high frequencies, and lets the low ones through, resulting in less loss of overall amplitude.
You coul then even insert such a filter in your speaker wires (for the whoofer), without having to mess around inside your amplifier.

Answer 3

A low-pass filter is a filter that passes low frequencies well, but attenuates (or reduces) frequencies higher than the cutoff frequency. The actual amount of attenuation for each frequency varies from filter to filter. It is sometimes called a high-cut filter, or treble cut filter when used in audio applications.

So to build one your gonna need to construct an electronic circuit:

Here's some schematics :
http://en.wikipedia.org/wiki/Low-pass_filter

Answer 4

ya definitely an op am....a resistor and a capacitor will do the magic...its a simple ckt...jus check third sem eng book for e and c...