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| Joined: | Jun 13th, 2011 |
| Location: | Florida USA |
| Posts: | 42 |
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I have constructed a gorgeously portable device out of a throw away computer speaker cube, batting and a plexiglass baffle. It will run for a few hours off of a 9 volt battery. Contained within the "cube" is another 8 Ohm speaker, hotglued to the inside. Opposite is a pickup mic. The plexiglass separates the input speaker and mic pickup from the speaker you listen to. Stuffed with batting it reduced (but did not entirely eliminate) back-feed whining. The other half of the interior is the original speaker and a very simplistic LM741 OpAmp cirtuit to drive a 2n2222 output transistor and the original speaker you listen to. The interior speaker is a very thin profile, plastic diaphragm type that came out of a weather proof radio that long ceased to function. It directly plugs with a pigtail into the headphone jack on the modded Radio Shack 12-587. I ghetto rigged the 9 volt battery to power the OpAmp and output speaker to the outside of the cube with a strip of electrical tape. Inelegant but it works.
Due to the nature of it's construction it zeroes in on what would be the natural frequencies and bandwidth of human speech, musical output is harsh, tinny - with emphasis in midrange. No bass is reproduced other than pops or clicks from interference. It was and remains a happy collision of mistakes and just getting lucky. :D