Film-Tech Forum ARCHIVE: Speaker Wire

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Topic: Speaker Wire

Bruce Hansen
Jedi Master Film Handler

Posts: 847
From: Stone Mountain, GA, USA
Registered: Dec 1999

posted 04-22-2002 04:14 PM

I don't believe that is due to skin effect, that may be more inductance. RF grounding is a very different story, snd 1.4MHz is WELL above 20KHz. What are you transmitting at 1.4MHz?

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Paul G. Thompson
The Weenie Man

Posts: 4718
From: Mount Vernon WA USA
Registered: Nov 2000

posted 04-22-2002 08:02 PM

Hi, Bruce.
Yes. That is our transmitter frequency. 1430khz on the AM commercial band. The other transmitter is 660AM. The 4-inch wide copper grounding has the surface for the skin effect to take place and carry the unwanted RF to ground, where a 12 gauge wire will carry practically nothing. There simply is not enough surface area to conduct it because of the skin effect, therefore making a 12 gauge wire look like a high-impedance circuit to RF. This likewise holds true for AM stations operating at 550 khz, but they don't need the 4 inch stuff. Three inches seem to work nicely.

I have not looked at a wave form on an oscilloscope for a sustained note on a distorted guitar like some of the hard punk acid rock musicians use, but if I did and measure the rise time and convert that to a frequency, it will fall in the RF range.

Sometime I will do that - just out of curiosity. Just how much attenuation a 12 gauge wire will actually give to a given RF frequency would have to be calculated.

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