Stereo receiver // an amp for my speaker systemBack in high school, I had a rather creative sound system thrown together from whatever speakers I could lay my hands on. This consisted of four speakers from a $50 Audiovox stereo (that didn't work), a 2.1 computer speaker system (powered, and not too bad for $20), and two ported enclosures I built for a couple drivers I had lying around from something. I figured the more speakers I had, the better surround sound I could get. So all in all, my setup comprised of 8 speakers and 1 subwoofer.
[p sound_system.jpg My beloved setup][p speaker.jpg One of the speakers I built]
Naturally, the challenge would be how to drive them all and have approximately equal levels from each. The 2.1 system was powered, would suffice for the low end, and had decent highs, but it was greatly lacking midrange. All my other speakers were passive, and being cheap full-range drivers really had nothing BUT a midrange. So the obvious solution was to build a stereo amplifier to drive those six speakers.
It's really an embarrassing setup for my then rapidly growing collection of studio gear... but it's what i had to work with. So with my limited knowledge of designing circuits, I resorted to digging through my pile of broken electronics and found a tape player that ended up working rather well. I was able to pull out the audio board and the power section, and then wire some inputs to where the radio module connected into the audio amp. Then it was a simple matter of building an enclosure with two pairs of RCA jacks for inputs and two pair for outputs, the AC power jack, and the volume and tone knobs. In addition, I put separate pots on the outputs to adjust the relative levels of the speakers. To wrap it up nicely, I cut some sheet metal from an old VRC and used it for the front and rear panels of the wooden box I built. And there you have it... a stereo "receiver" from an old tape player!
[p amp_front.jpg Front][p amp_back.jpg Rear][p amp_inside.jpg The audio circuity][p amp_inside_2.jpg The power section]