[sdiy] On shielded cable (or not) for audio

[Antti Huovilainen]

On Tue, 7 Jul 2009, Scott Nordlund wrote:

> I think this could use a little more elaboration...
>
> (a) (coax) would mean that the wire is carrying the signal and the 
> shield is grounded.  The shield doesn't have to be connected on both 
> ends, but it may help (assuming it doesn't introduce ground loop 
> issues...).

> For (b) (twisted pair) to work as described, the wires must carry 
> complementary currents, the signal and its return path, as this is the 
> "loop" (which couples to some other "loop" like a transformer, the 
> amount of coupling being proportional to the loop's enclosed area).

True. I forgot to mention this in my posting. In the tube heater case, 
this is obviously true as the heater has just two connections in use.
In a modular this is not likely for the signals, but might be possible in 
the PSU. Then again, tube heater currents are in amperes, while a module 
might require just tens to hundreds of milliamperes.

> Of course you could also use optical fibers....

Or balanced inputs and outputs (most likely an overkill).

Antti

"No boom today. Boom tomorrow. There's always a boom tomorrow"
   -- Lt. Cmdr. Ivanova