Q:I’ve noticed that mic, guitar, and line signal wires are shielded, but loudspeaker and power cables aren’t? Is there a reason to shield some and not others?
It seems like it would make sense to at least shield the power cables, especially given all the problems that power cables can cause.
A: An interesting observation!
Line, mic, and guitar cables are shielded because those signals are greatly amplified before they are converted back to sound waves. Any noise that those cables pick up along the way would also be similarly amplified and become audible.
Similarly, AC power is never amplified, and loudspeaker-level signals are already amplified before they pass through loudspeaker cables. So, while you’re correct in your observation, the cables which are shielded are those which are susceptible to interference and noise.
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