Introduction:
A woofer is a type of speaker that is designed to reproduce low-frequency sound. It is commonly used in audio systems to enhance the bass response. When feeding a woofer with an audio signal, it is important to ensure that only the low-frequency components are passed through and that the higher frequency components are filtered out. This is where a low-pass filter comes into play.

Explanation:
A low-pass filter is a type of electronic circuit that allows low-frequency signals to pass through while attenuating or blocking higher frequency signals. It is designed to have a cut-off frequency above which the signal is significantly attenuated. In the case of a woofer, the cut-off frequency of the low-pass filter should be set to a value that allows for the reproduction of the desired low-frequency range.

Advantages of using a low-pass filter:
1. Enhanced bass response: By using a low-pass filter, the woofer is only fed with the low-frequency components of the audio signal, allowing it to reproduce deep bass sounds more effectively.
2. Protection against damage: High-frequency signals can cause distortion and damage to a woofer if they are not properly filtered out. A low-pass filter helps to prevent this by blocking these unwanted frequencies.

Why not other filter options:
1. High-pass filter: A high-pass filter allows high-frequency signals to pass through while attenuating or blocking low-frequency signals. Using a high-pass filter to feed a woofer would result in the elimination of low-frequency components, leading to a loss of bass response.
2. Band-pass filter: A band-pass filter allows a specific range of frequencies to pass through while attenuating or blocking frequencies outside this range. While it is possible to use a band-pass filter to feed a woofer, it would require more complex circuitry to set the desired frequency range. A simple low-pass filter is usually sufficient for this purpose.
3. Band-stop filter: A band-stop filter, also known as a notch filter, attenuates or blocks a specific range of frequencies while allowing others to pass through. Using a band-stop filter to feed a woofer would result in the elimination of the desired low-frequency range, leading to a loss of bass response.

Conclusion:
In conclusion, a woofer should be fed from the input through a low-pass filter. This allows the low-frequency components of the audio signal to pass through while attenuating or blocking higher frequency components. This ensures enhanced bass response and protection against damage to the woofer. Other filter options such as high-pass, band-pass, or band-stop filters are not suitable for feeding a woofer as they either eliminate low-frequency components or require more complex circuitry.