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Sound Artifacts of Cheap Ground Loop Isolators?

Fence_Seagull

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So, I'm using RCA to connect to my amp, but I get hum.
I stuck a cheap $10 amazon ground loop noise isolator in and it's definitely a big improvement, since I don't hear any hum anymore.
But, I'm wondering if they introduce any audio artifacts.

I could go a balanced chain, but that seems like a big step up in price as compared to a $10 dongle, and I am skeptical that outside of the noise isolation, that I would get a big sound quality improvement.

I'm also curious as to how these cheap things work, if anyone has an idea.
 

alex-z

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Even the good ones aren't problem free, the THD+noise ratio gets worse at low frequencies, and as voltage increases. On the Jensen ISO Max it shouldn't be audible, but on cheap units it can be.


It is generally better to find and fix the source of the ground loop, rather than use an isolation transformer.
 

Lambda

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I'm also curious as to how these cheap things work, if anyone has an idea.
it's a small transformer. it converts the electrical signal to a magnetic signal and back.
This way there is no galvanic (electrical) concretion between input and output. (for low frequencys)



I'm wondering if they introduce any audio artifacts.
Yes.
Increased Distortion and compression at low frequancys levels.

This is the typical Transformer sound. many call it "tube sound" beaus almost all tube amps have transformer in or outputs.
So it is "Warm and smooth" :p
If you want more fancy adjectives:

But if you don't hear it its maybe fine.
The effect highly depends on the level you drive the transformer with.
 

Katji

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It is generally better to find and fix the source of the ground loop, rather than use an isolation transformer.
+1. isolation device only if fixing is impractical - like changing wiring or whatever, like in a rented place.
 
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Fence_Seagull

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it's a small transformer. it converts the electrical signal to a magnetic signal and back.
This way there is no galvanic (electrical) concretion between input and output. (for low frequencys)




Yes.
Increased Distortion and compression at low frequancys levels.

This is the typical Transformer sound. many call it "tube sound" beaus almost all tube amps have transformer in or outputs.
So it is "Warm and smooth" :p
If you want more fancy adjectives:

But if you don't hear it its maybe fine.
The effect highly depends on the level you drive the transformer with.
Oh, I see. This article basically answers all of my questions about what they are and what they can affect, thank you very much! Along with the measurements posted of a much more expensive device as a representation of a "good transformer," thanks, this is pretty much exactly what I wanted to know!

Lol, are you saying that this cheap transformer can give me an impression of what the "tube sound" sounds like?
 

Speedskater

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A long time ago, Arny Krueger (RIP) tested the Radio Shack unit:

Some very decent audio isolation transformers are widely available as the Radio Shack ground loop isolator:
I did some bench testing of it a few years back. 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 also did some experiments with varying the source
and load impedances. My recollection is that the transformer is reasonably
non-critical with normal audio production source and load impedances for
line-level equipment. It looks like it will also work fairly well with
consumer audio gear, which is of course what it was intended for.

The Jensen Isomax serves a similar purpose with slightly better performance:
 
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F

Fence_Seagull

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So, I found out when trying to EQ my headphones and using pure frequencies to test it, that mine sounds very much like the one in the article linked above:


There is a massive boost around 30 Hz and below that is very, very distorted.
 

fpitas

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Oh, I see. This article basically answers all of my questions about what they are and what they can affect, thank you very much! Along with the measurements posted of a much more expensive device as a representation of a "good transformer," thanks, this is pretty much exactly what I wanted to know!

Lol, are you saying that this cheap transformer can give me an impression of what the "tube sound" sounds like?
Yes; for years engineers labored to eliminate transformers from the signal path. Now it's trendy to put them in.
 

fpitas

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That was because they are big, heavy and for the good ones very expensive.
And even the very best were band-limited and distorted, especially at the extremes of frequency. They even have a vague sort of "crossover distortion" when the flux reverses.
 

dominikz

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So, I'm using RCA to connect to my amp, but I get hum.
I stuck a cheap $10 amazon ground loop noise isolator in and it's definitely a big improvement, since I don't hear any hum anymore.
But, I'm wondering if they introduce any audio artifacts.

I could go a balanced chain, but that seems like a big step up in price as compared to a $10 dongle, and I am skeptical that outside of the noise isolation, that I would get a big sound quality improvement.

I'm also curious as to how these cheap things work, if anyone has an idea.
Perhaps you will find this thread useful, where I compare a few ISO devices (+ other similar devices).
As others have stated, transformers will usually saturate at low frequencies and high levels (which results in increased distortion and sometimes even frequency response deviation) and you will also see differences in noise rejection between different units. Even cheap units can work very well if you only need low levels (and in any case a little distortion is normally preferable to ground noise :)).
Transformer performance in my experience varies hugely, and unfortunately the best ones are usually not cheap.
 
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