"Andy" wrote in message


I want to use an audio transformer to see if it helps to
reduce the ffect of an earth loop.


Go straight to Radio Shack and get their "Ground Isolator".

I've tested them on the bench, and they aren't all that bad.

I just did some bench tests of Radio Shack's "Ground Isolator" 270-054 using
test signals that maxed out around 2.5 v RMS. ZSource = 150 ohms, ZLoad =
5Kohms.

The measured performance was truely amazing for a pair of transformers case
and cables selling for only $16.65.


All IM, THD, and noise artifacts were at least 80 dB down with most in
the -100 dB range or better. Frequency response showed a 2 dB peak at 20 Hz
and then 10 dB down at 10 Hz. There was a 3 dB peak at about 51 KHz falling
to about 10 dB down around 100 KHz. +0.5 dB at 20 KHz.

I repeated the tests with the secondary loaded with 1.5K, and the peak at 51
Khz became well-damped with only about 0.6 dB rise.