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It’s easy to upcycle old cassette boom boxes into general purpose amplified speakers. Cassettes are mostly obsolete and there are plenty of working used cassette players available for almost nothing. I recently picked up a portable karaoke cassette player for $1 at a yard sale. The seller apologized that the microphone wasn’t working anymore, so it would only play cassettes, but that was fine by me.
In theory you can disassemble the boom box and solder wires directly to the circuit board’s audio inputs, but there’s a far simpler solution – a car cassette adapter. These handy devices were originally designed so cars with cassette players but without built-in CD players could use a portable CD player. Now they’re marketed primarily to hook up an MP3 player to a car’s stereo system. They work fine for non-auto applications and you can pick up used ones at yard sales and thrift shops for about $1.
The main difference between car cassette players and most boom boxes is the orientation of how the cassette is inserted. In cars they’re inserted sideways (small side) while in most boom boxes they’re inserted flat, either on the top or front.
With a car stereo the adapter’s cable comes out of the front of the unit. It’s slightly trickier with a boom box since there’s no opening for the cable. In most cases you can just squeeze the cable through the opening without any problems. In others you may have to notch a hole in an appropriate place for the cable to pass through.
Cassette adapters must be inserted right side up. As a normal rule it’s the side with the label.
All you have to do is press play on the cassette player and you’ve got an amplified speaker.
Step 3: What Can You Use It For?
I’ve used this setup as a portable set of computer speakers (especially useful if you’re playing music or a video on a laptop computer in a portable situation, with MP3 players, as a speakerphone with my cell phone, and other cases where I’ve needed portable amplified speakers.
Check out the complementary instructable, reusing computer speakers, for another approach.