Audio filtering, experiment 29 of Make: Electronics part 3

A small update on the filtering experiment 29 of Make: Electronics that I wrote about earlier this week. To improve audibility especially of the lower frequencies I had to built an enclosure. The book proposes a plastic box but I had a shoebox made out of cardboard lying around. I cut a circular hole in it just wide enough to fit the 4-inch speaker and fastened it with four bolts and nuts. I placed the breadboard with the amplifier on the bottom of the shoebox. I connected the audio and power and filled the box with isolating material. Then I played a track unfiltered, with low pass filter and with high pass filter. The box definitely made an big improvement to the sound. Conclusion: a shoebox can make a tolerable (and cheap) enclosure for a speaker.

Cardboard box with speaker built in. Labbench and iPod for power and audio-in respectively. 

Breadboard on the bottom of the shoebox with the coil clearly visible. The coil acts as a low pass filter.

Shoebox stuffed with isolating material in an attempt to improve the sound for this experiment.

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