Subwoofer circuit diagram:
This is the Low pass filter circuit diagram. If we want to make Sub-Woofer then we have to use this circuit as a pre-amplifier. This circuit makes the only bass. This is the best subwoofer circuit diagram. and it’s also so easy to make.

Here in this circuit used 4558D IC.

About this IC
4558D is a dual operational amplifier.
Excellent channel separation allows the use of a dual
device in a single amp application. The SE/SA/NE4558 is a pin-for-pin replacement for the
RV/RM/RC4558.
# 2MHz unity-gain bandwidth
# voltage ±18V for NE4558 and ±22V for SE4558
# It also Short-circuit protection.
#No frequency compensation required
#Large common-mode and differential voltage ranges
#Low power consumption.

This is a mono circuit diagram. If you want to make stereo subwoofer then you have to use 2 Pieces of the circuit.
This is PNG for print out. download and make your self.

Please watch this video. this video about those circuit
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