How to improve the sound quality of bad sound stuff

Ok, so I'm not going to claim to be able to fix EVERY gadget out there that sounds bad, but if you have an el cheapo stereo, this might help. For me, it's a ~25 year old JCPenney stereo (I didn't know they made stereos!) that I bought at a garage sale. First ever stereo and I recorded some stuff on it and listened to Scott Joplin records constantly. However, after a while I drifted away from it and so now I'm coming back with a bunch of new record albums. I hooked it into my sound system, but it sounded horrible. It had a low frequency hum so loud that it lit the -20db light on my board--not good. And if I turned a knob, it put out so much static it was unbearable. So, I went to open it up and see what I could do.

Opening it was easier than I expected. There was three screws on the bottom:I unscrewed them and the bottom cover came off and I could see pretty much everything. I looked around and the first thing I noticed was that the wires for the output jacks ran right past the power cables and a transformer! As well, the power cables and the speaker cables were unshielded and not even twisted together. Now, this is about the best recipe for static hum in a system.

But, I know a fix! The official way is to rewire it with shielded twisted-pair cables and ferrite cores, but you can do it ghetto style and just twist the wires around each other and wrap it in heavy-duty aluminum foil: Unfortunately, I was unable to get the circuit board off to access the knobs (but I have another idea if I get some time). I put the cover back on. Then I did another great DIY way of fixing dirty knobs: twisting them back and forth quickly ad nauseam.

Testing: I plugged it into my stereo and turned everything on. The first thing I noticed: no hum whatsoever. I turned the gain and mains up all the way and I could hear some hum if I put my head next to the speaker, but nothing like it was! I twisted a couple of the knobs around and no static.

Listening: I seriously didn't know records sounded this good! Sure, there are limitations to the album recording methods (notably, lowered frequency response in the middle frequencies and the tendency towards hypercompression on the inner tracks), but they sound remarkably better than before.

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