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Microphone vs. Speaker wire
Posted 28 August 2012 - 08:48 PM
Posted 28 August 2012 - 08:53 PM
In the case of a mic, any incoming or stray interference is going to be amplified multiple, if not hundreds (thousands) of times in order to have enough of a signal to drive a speaker via the output section of an amp.
Posted 28 August 2012 - 10:20 PM
Now an inexpensive microphone is likely to be putting out fractions of a volt - and its likely on a much higher impedance line.
So if both are in the presence of a source of interference the higher voltage and lower impedance of the speaker line is going to make it much less susceptible to the interference.
Posted 29 August 2012 - 02:06 AM
Posted 29 August 2012 - 12:29 PM
The voltage output from a microphone is very low; typically about 0.001V. It's so low that when you string unshielded cable about 25 feet or more it tends to pick up AC powerline hum, AM radio, and a lot of other noise. The unshielded cable tends to act like an antenna. Once the microphone signal is at your panel (or where ever it's going) there is an amplifier that will boost this low level to about 1V. Problem is it's also boosted all the hum and other noise too.
The two ways around the problem is to either use shielded cable (blocking the antenna effect) or put the microphone amplifier at the microphone. Remember that shielded cable should have the shielding wire connected to ground only on one end, not both ends. It's generally best to do it at the panel end instead of the microphone end, but that can vary.
Regarding the wire gage. It's not important. The thinner stuff (22 through 26) is just fine. Shielded speaker wire will work, but is a waste of money.
Edited by Mr Spock, 29 August 2012 - 12:41 PM.
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