audio wire shielding

[jake08]

I am replacing my speaker wire.I am using silver coated copper.Ihave to run it up a 12ft. wall then 20 across the ceiling, then down another 12ft wall.My brother claims that shielding is imperitive.Does anyone know where I can get shielding or would metal conduit work as well.

[Don Richard]

Shielding is generally unnecessary unless your equipment has noise pickup problems. However, if you want the lowest inductance and lowest capacitance speaker cable, RG-8 or RG-11 coax can be used. This cable is good for about 2KW of RF power so should be able to handle any amp you are likely to use.

[tube fanatic]

Shielding is generally unnecessary unless your equipment has noise pickup problems. However, if you want the lowest inductance and lowest capacitance speaker cable, RG-8 or RG-11 coax can be used. This cable is good for about 2KW of RF power so should be able to handle any amp you are likely to use.

I disagree about using coax for a run of that length. RG8 type coax has a capacitance of around 26pf/foot, and RG11 around 20pf/foot. The total capacitance of a 44 foot run could affect your frequency response. Assuming that your house is wired with Romex (which can radiate powerline grunge quite nicely), and not BX cable (which is self shielding), you would be better off using a good quality #12, or even #10, wire routed through grounded steel conduit. In fact, I've had good luck using steel jacketed BX cable for speaker runs like that. It's relatively cost effective, and provides a nice low resistance signal path to the speakers.

[Don Richard]

I disagree about using coax for a run of that length. RG8 type coax has a capacitance of around 26pf/foot, and RG11 around 20pf/foot. The total capacitance of a 44 foot run could affect your frequency response.

Most cable used for loudspeaker service is the same or worse, capacitance-wise. It won't make much difference @ 4 or 8 ohms (tube amp) and no difference @ .01 ohm (SS amp). The value in using heavy gage coax is low resistance, low inductance and, possibly, shielding. These cables are used in RF service up to 250 megahertz or so.

[CECAA850]

Is your wire rated for in wall use?

[InVeNtOr]

shielding is only important if you have rfi/emi issues. the easiest and cheapest way would be to get some twisted 12 awg wire and call it good. usually speaker wire is too low of power and only 60hz so interference is rare when it comes to the wire to the speakers.

i would say, if you don't hear an issue now, stick with what you got.

[PrestonTom]

There are two considerations.

1. Length: This requires heavier wire (gauge: the lower the number, the better). Coax is a very light gauge.

2. Impedance: The higher the impedance, the greater need for shielding (so as not to pick up interference from EMI or RF). In interconnect from a source to a pre-amp or to an amp is a high impedance (say 20kOhm to 100 kOhm) and requires shielding. In contrast, a speaker wire is going to crossover/speaker that presents an impedance that is 3 orders of magnitude less. So it is unusual for speaker wire to pick up any junk (not a technical term).

If you have hum or hiss in your system, look elsewhere for the culprit.