Originally Posted by brian6751
Originally Posted by arnyk
My ground loop isolator had the same problem, which I resolved by putting it into an empty tomato paste can. I even found a jar cap that was a tight fit in the can, punched a hole in it, and slipped the wires through it for a more finished appearance.
Was that to get rid of the hum or were you getting distortion as well?
The can was to get rid of the hum.
I've done some bench tests on the RS ground isolator and its hard to imagine how it would cause audible distortion with consumer gear. No consumer gear should be putting out more than a volt or two, and at those levels the thing has very low distortion.
The only way I can figure out to make it distort would involve an active subwoofer with a very insensitive input, or its input level control turned way down.
I don't know about competitive items.
Here's my test results from an earlier post on a different forum:
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 =
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.
I found another guy's tests online:
I bought a RadioShack "Ground Loop Isolator" today and decided to test the IMD of the transformers (there are two in the device).
I used Digipan in its IMD measurement mode and looped the output of my soundcard directly back into the input with a
straight-through cable. Playing with the output and input levels, the typical IMD measurement in Digipan was about -61 to -58. I
then inserted one of the transformers of the RadioShack device and the IMD did not change. I played with the levels and was able to
put the transformer into saturation and could see the signal in the display, but with every level tested, and regardless of
frequency (used 1kHz, 2kHz & 3kHz) when the level was below saturation there was no difference whether or not the transformer was in
I was expecting a higher IMD reading with the transformer inserted between the input and output of the soundcard as compared to the
straight-through cable. What am I missing?
73, Don AA5AU