Technically, what you need is an RCA to mini-phono stereo cable, in all likelihood.
Most tape decks (like most stereo components) have RCA jacks -- they're the ones that look like nipples. Most soundcards have a "line-in" jack that's a mini-phono. In the U.S., they're also called 1/8-inch jacks. The same size as a walkman headphone jack.
So, what you're doing is replacing your stereo tuner with the computer, as far as the hookup goes. the cable that goes out to your stereo, you replace with one that goes out to your computer. (You can also do the same thing by getting a cable to hook the headphone out to the computer in, if you need to, but that probably won't be necessary.)
That's the easy part. The tricky part is what happens to the sound signal once it's coming out from your tape deck into the computer. Every computer nowadays has some kind of native audio recorder, pretty much. On the mac I'm writing this on, there are several -- it came with GarageBand, which I'd probably use just out of familiarity's sake if I didn't have better audio software specifically designed for recording (and editing) audio files.
I think you're on Windows, so the audio recorder on your machine will depend on what version you're using and what soundcard you've got installed (SoundBlasters come with some pretty cool software, if memory serves). If you go to Help and look up ".wav files" or "audio recording" or something like that, you'll find the software.
Generally, the interface will look something like a tape recorder -- all you have to do is hit "record" and the program will record what comes through the soundcard. Hopefully, your software will also include some kind of level monitor so you know what volume that signal is coming in at -- if it's too high, it'll be all distorted and nasty. Usually monitors are color-coded bars, with green being "low", yellow being in the middle, fading up to red for "too hot." Just like on a tape deck, you want the level to be riding somewhere in the low-yellow area most of the time, with occasional bumps into the red for, like, the very loudest fraction-of-second hits during any given song.
Some software allows you to adjust levels right there, but even if yours doesn't, you can simply double-click on the little speaker icon that controls volume, which should display the "advanced options" screen. Somewhere in there, you'll see a "line in" volume slider that'll adjust the volume to the right level.
OK, so once you've done that, you've got an audio file that'll in all likelihood be a .wav file (on a mac, it'd be an .aiff unless you're being fancy). An average size for a 3-minute pop song is around 30 megs. This is why mp3s were such a big deal -- convert the .wav to an mp3 and it'll be around 3 megs. So, unless you're like made of hard drive space, you'll need to get some kind of "ripper."
The latest version of WinAmp, the popular, free mp3 player, will convert wavs to mp3s I think (although I'm really not sure) -- you just have to navigate to Options/Preferences/I-O, and change the output from "WavPlayer" or whatever it is to "DiskWrite" or similar. iTunes I know will do this automatically, practically -- just add the wav to your Library, go to Advanced, then Convert to mp3 (you may have to change the settings on the "convert to-" option, since it'll also convert to other formats). Or, you might just have to get another ripper. I like AudioCatalyst, since that's what I'm used to, but there are plenty of others out there -- probably some that are freeware or demoware.
So that's about it. Make sense? |