ok, so i have these midi files on my computer.

so yesterday, i was going thru them and i noticed how well this one program played midi's. i mean, for every program, the instruments sound different.

so i hooked up his computer's line out port to my line in port and tried to record. once i was done, i listen to it, an there is this horrible noise in the background. and it sounds really bad.

but before i started to record, i listen to it from my computer from the line in port, and it sound awesome! so I'm not sure why it sounds terrible when recording, but when I'm just listening to it, it sounds fine?


thanks,
rabbit2345 ^_^

So wait, you physically connected the line out and line in jacks?

You're going to want to watch the VU meters on audacity. You're probably either overdriving or underdriving by a bunch. Either one would be a source of noise. Oh, and I've heard of people doing the same thing to get a song from youtube. Not that I'd ever suggest doing that, of course.

yes, i have a stereo cable to connect the in/out ports.

and quakeboy, could you clarify what overdriving or underdriving is? and where is the VU meter in audacity?

Right above the picture of the microphone there should be two level meters labeled "L" and "R". If those ever get above about -3 then they probably are going to 0. Anything past exactly 0 is called saturation, and will cause very bad distortion. Normally I try to record so that the highs never go above -3 or so. It's easy enough to make a pass through and normalise the volume after you're finished recording. OTOH, if the levels are very low, then you will get distortion from the amplifier circuits as you raise the volume to recordable levels. Watch the recorded waveform. It it flatlines anywhere then it's saturating and will sound bad. But, if the levels are nowhere near the top, then it's not going to sound good, either.

Definitely watch the VU meters, if the signal saturates then you are not going to get a clean signal. However, I wouldn't expect a good quality from this inputs and outputs.

The cool way to do it would be via a Direct Injection box, but you are probably not willing to invest money just to record one song. You could try the mic input, it's probably better suited for louder signals, but I wouldn't hold my breathe for it.

Actually, I've gotten good quality doing a loopback like he's talking about. It's common to do a loopback with the ham radio program MMSSTV to calibrate the sound card. They're always off by enough to cause sync problems with SSTV (Slow Scan TV).

Dangit! I didn't read this closely enough. i92guboj was right! Since you are hooking up two different computers, you need a box. What you're getting is a groundloop, and what you're hearing is called common mode hum, I think. If you look on the net, you can find audio isolation transformers. They make them in singles with RCA plugs, which is what I use (with adapters) for recording between two machines. They also have them with stereo plugs and jacks so that you can hook them up directly. If you know which end of a soldering pencil is hot, get a pair of 600 ohm audio 1:1 transformers from Radio Shack (assuming they still sell them) along with a stereo plug and jack. Make sure that the grounds are NOT connected from one side of the transformer to the other. You want the computers completely isolated.