Small active subwoofer to use with a TV

subwoofer pictureI use modified pc speakers with my tv but I wasn´t happy with the bass response. So I made a small subwoofer that fits neatly on a shelf under the tv. Since I didn´t have a special subwoofer element I used two ordinary speakers thinking they might work well enough.

I kept the circuit simple: a single power supply, TDA2040 power amp and a passive low pass filter. Controls are volume, filter cut off and phase switch.

I am very happy with the result. After some fiddling with lpf and eq of the main speakers I achieved a pretty nice overall response. Ok, this sub is not very loud - no shattering windows here! It still makes a big difference at normal tv listening volume (and made from junk it didn´t cost anything).

simplified schematic

©Jukka Korppi 2015
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