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AC line noise
AC line noise
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Old 7th May 2021, 07:03 PM   #21
rayma is offline rayma  United States
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Join Date: Apr 2011
Try plugging the AC and stereo into different, widely separated outlets.
Run an extension cord if necessary for the test.
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Old 7th May 2021, 07:31 PM   #22
johnnyk9 is offline johnnyk9  United States
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Join Date: Sep 2009
Location: TEXASS!
I have, it made no difference in the noise.
Thank you though.
I am going to check how the outlet is wired this weekend if I have time.
Iím racking my brain trying to decide what to get my mom for Motherís Day at the moment...
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Old 7th May 2021, 07:35 PM   #23
johnnyk9 is offline johnnyk9  United States
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Join Date: Sep 2009
Location: TEXASS!
Quote:
Originally Posted by peufeu View Post
Can you post a link?

> If I unplug the RCA cables from Purifi amp it is absolutely quiet.

OK. Things to try:

Amp without any cable: quiet.

Plug in just the single ended to balanced converter, with no cable connected to it. Noise?

Plug a cable on the converter, leave other end of cable unconnected. Noise?

Short signal and ground at end of cable (you can use a RCA plug or cut off a junk RCA cable and solder the wires together).

Make contact between the shorted RCA connector made at previous step and the ground of RCA on your source (just ground, no signal).

Connect ONE rca cable, not two (one ground loop at a time!)

etc...

Basically, divide and conquer, try to find one difference that makes the noise appear or not.
Thank you for the very thorough troubleshooting sequence but, I have discovered that my outlets may not be properly grounded.
Old house blues....
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Old 7th May 2021, 07:55 PM   #24
duncan2 is offline duncan2  United Kingdom
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Join Date: Mar 2013
Location: Scotland.
Borrow an ELT -earth loop tester , the resistance should be less than an ohm .

Using my old Megger LT5 ELT at this moment on my sockets I get a reading of =0.26 ohms .

You do realize in the UK and I hope in the USA a high result doesn't just help to transmit noise but is highly dangerous when it comes to electric shocks ?

Due to my good earth I am not bothered with domestic appliance noise even with a 100Kohm input impedance but I use JLH,s earthing /earth return principles .

Do not connect an "earth " to a gas main do a bit of wiring to the nearest good earth or if you have a garden then a long earthing rod deep in the ground does the trick.

I know personally many USA citizens who have had to run their own earths , while 115V AC might not kill somebody with a good heart not everybody has a good heart and body resistance comes into it.
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Old Yesterday, 01:25 AM   #25
johnnyk9 is offline johnnyk9  United States
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Join Date: Sep 2009
Location: TEXASS!
I have an Insulation resistance tester, which I believe is the same as a Megger.
I picked it up to test 3 phase motors as I am a maintenance man, or should I say I was a maintenance man. I was laid off due to a combination of COVID-19 & our government going down the gutter post elections....
Sorry for the sidetrack....
Yes, not grounding to gas mains.
The way this house is built, with me being on a slab, rest of house on P&B, brick sidewalks, decking and stairs ....running wires will be extremely complicated.
I do know a bit about grounding and bonding as they say in the field, but isnít having 2 ground rods a bad thing without a separate dedicated circuit?
Appreciate all the information I am receiving,
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Old Yesterday, 01:33 AM   #26
rayma is offline rayma  United States
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Join Date: Apr 2011
Usually two ground rods are bad. Can you have a local licensed electrician take a look at your wiring?
Do you have significant AC voltage on your outlet neutrals?
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Old Yesterday, 03:18 AM   #27
NareshBrd is offline NareshBrd  India
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Join Date: Oct 2017
Location: Baroda, Gujarat, India
Old style earthing was a 3 foot deep pit , put a piece of cast iron or thick plate, connect with galvanized wire.
Put a plastic pipe for refreshment.
Cover plate with salt and charcoal, and close up the pit.
Add water, and top up periodically, every six months or so through the pipe, occasionally brine will be needed.

Plate about 12 to 24 inches square, at least 3/4 inches thick.


Chemical earthing the method here is to drill a 4 inch hole like a bore well with casing pipe 10 feet deep, add the special chemical for the bottom 6 feet, and run the wire out.


But that would need a soil drill.
Buried metal is easier, you can buy an old engine block in scrap, it will have tapped holes too, small engine or whatever.


Maybe you know all this already.
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Old Yesterday, 08:59 AM   #28
duncan2 is offline duncan2  United Kingdom
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Join Date: Mar 2013
Location: Scotland.
First of all the name may be the same Megger but an insulation tester and an EARTH LOOP tester are not the same nor do they test in the same way.

An ELT tests positive to neutral /positive to earth and displays a reading ( in my case digital ) of the actual earth resistance in other words 3 tests are automatically done in relation to the positive ( USA HOT wire ) .

In the USA it used to be the case that only 2 connections existed but now there are 3, due to distances many USA homes have a local earth .

In answer to "bad practice " -two earths this is down to the different wiring standards in the USA & UK .

In the UK its whats called "ring main " circuits with spurs and there is more than one ring main that's why I advised a local earth as it would apply to a UK mains wiring situation as the "bad " earth circuit can be cured by providing a local earth which does not effect the other ring mains or spurs .

Earth loop impedance testing demystified | Megger
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