Reducing noise and crackling from wires

Question

I'm looking for advises on how I could reduce crackling and noise when recording from line output to line input (big jack stereo wires).

Actually I output the sound from a keyboard synthesizer to the line input of my sound card.
With a small mix table in the middle to monitor the levels and output the master signal to a speaker.
The wires are quite long and I can hear noise from the FM (or maybe AM) when recording.

I try avoiding recording at maximum output vol. to avoid saturation.
So I record just below the limit of saturation but the resulting sound recorded is quite low and any attempt to increase the volume shows up the noise and crackling.

Could you advise me on how to reduce this effect, or point me to relevant information source on how to properly perform a sound record ?

Answer 1

Balancing! All your lines should be balanced. What this does it splits the signal in two and flips one half of it. Then the side that is flipped is flipped back at the end, and added to the first one, therefore cancelling the noise induced in the cable out. You need a DI box, especially since your cables are long and then something to unbalance the signal at the other end if your equipment can't take a balanced input, like a Reamp or something.

Balanced stereo obviously requires two cables and two DI boxes. Behringer do a good budget solution that can be used at both ends (as it's just a transformer) call an Audio Line Isolator -- just use it in reverse at the other end if your kit doesn't take a balanced input. That will certainly remove all the FM/AM interference, and maybe some crackling. But you should be using a balanced feed for long cables regardless. Let us know how you get on!

Answer 2

If you're using a hard wired setup and you get crackling noise/noise reduction it could very well be that something in your chain line needs to be repaired. The cord may be old or rusty.

Tell me if I have this right:

Synth -> Input (software mixer) -> Output(Speaker)