On 2/2/2012 8:00 AM, k3miy@csonline.net wrote:
I, and others, know of properly terminating
an audio input to avoid ground loops and potential RFI. Usually this is
done by the input device(mike, amp etc). In a test situation, a termination
resistor that doesn't draw any current does the same thing.
A termination resistor will draw as much current as Ohm's Law dictates
as a result of the voltage across it. Actually, audio interconnects are
NOT designed to be terminated by resistance, and have not been for at
least 40 years. That USED TO BE the practice, in the days of vacuum
tubes, but since at least the 70s, audio output stages are designed to
NOT see a load resistance or impedance. In fact, output stages want to
see load resistance equal to at least 5 times their output impedance,
and a higher impedance is better. The only folks who haven't gotten the
word are those working in ham radio -- the broadcasters figured this out
in the 70s.
73, Jim K9YC
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