Hello
I have a tpa3118 amp fed by a laptop running Daphile music server. Quality from the headphone output is just tolerable into amp and wharfedale 9.1s.
Problem came when I tried to use the same PSU. for both amp and laptop. Now I have got ground loop noise as laptop boots.
The question is will a ground loop noise isolator filter for 3.5mm aux cable help and will it sap the quality even further.
I have a tpa3118 amp fed by a laptop running Daphile music server. Quality from the headphone output is just tolerable into amp and wharfedale 9.1s.
Problem came when I tried to use the same PSU. for both amp and laptop. Now I have got ground loop noise as laptop boots.
The question is will a ground loop noise isolator filter for 3.5mm aux cable help and will it sap the quality even further.
I would build up the the amp with mid z transformer inputs, and have ground lifted rca connections.
IME, sharing a PS between two components always produces problems. The optimal solution - which I suggest is the only one, for good sound ... is to buy a 2nd PS.
I would just get a usb interface with xlr outs and make the amp balanced in. The laptop audio is corrupted even before it leaves its outlet.
How does someone know they have a ground loop problem? Also, what makes them think they only have one problem?
Please describe your system, show a block diagram of how the power is connected to produce a ground loop, and describe what testing you have done to know that a ground loop is a problem?
Maybe to some extent. We need to know more details about your system, what you are hearing, etc. As I just asked the other gentleman, we need to understand your system and how its configured. Your job in this effort is to make it easy for us to understand what you are doing, how your system is hooked up, how its powered, etc., in detail. In this type of situation specific details matter. While what you have may be quite obvious to you, we aren't there and can't see it for ourselves. Help us out here and we will try to help you.
Its important to get the right USB interface and hook it up correctly. There are various things that are easy to get wrong for a beginner in this area of audio.
Not sure if your reply is directed at this:
... but it seems DIY-lover has a house with a bad (ground) earth and he's asking what to do about it.
@DIY-lover , you need to get an electrician in, to re-do your ground-earth connection as - if it's bad - you are in an unsafe situation.
Earth rod or plates/mats.
Plates are often used by EV owners because many chargers won't work unless there is a low impedance ground connection.
A copper rod works unless you are in a very dry location, otherwise ground plates are buried as deep as needed to achive a low impedance.
E.g. https://www.churchillsc.co.uk/product/electric-vehicle-charging-point-earth-mat-kit
1-My voltage tester light was on when I connected it to my PC case. 2- Connecting one of my multimeter probes to the case and another to my hand. There was an inductive voltage of about 15 volts. It doesn't mean it shocked me but it is enough to make everything noisy.
That doesn't necessarily have anything to do with a ground loop. However, if he wants to know what to about an earth ground problem, I would still like to know what makes him think there is an earth ground problem. That said, obviously the safe thing to do is call a licensed electrician to check the system, especially if there a symptoms indicating a possible problem.
What do you mean by saying your voltage tester light was on? What kind of a voltage tester do you have? Does it have leads or does it have a plug? Only one light, or a few lights on it? Does you computer have a 3-wire grounded cord (like a desktop computer), or does it have an external power supply module with a two conductor cable going from the power supply module to the computer?
Also, when you connected a meter probe to the case and other to one of your hands, where was your other hand? IOW, where is the circuit loop? And what do you mean by an "inductive voltage?" Do you mean you know a magnetic field induced a voltage potential between two points? If so what makes you think a magnetic field is involved instead of an electrical field (the term field is being used in the near-field sense here).
Maybe it would help if you can you take pics of what you are measuring so we can see what the test instruments look like and what is connected to what?
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Markw4
A neon screwdriver.
I think it was an inductive voltage. The test is very simple. Set your multimeter on AC voltage test. Connect one of the probes to the PC enclosure and another one to your hand. If there is a voltage it will be a kind of inductive voltage and it means the earthing system doesn't absorb the inductive voltage of the PC case body.
Your body has capacitance to ground. Your meter probably has a 10M impedance. What you have is circuit formed by loop where your body capacitance to ground is in series with the meter.
Still don't know if your computer case is grounded or not? Is grounded to the AC line with a 3-wire AC line cord? Its it desktop or laptop?
What frequency is the voltage you are measuring when you are acting like an antenna with your hand on the meter lead? Is it 1MHz or is it 60Hz? IOW, is it from an SMPS or from the AC line?
Anyway, a better test would be to measure from the computer case to a cold water pipe somewhere. Also measure not just from the computer case, but also from the screw that holds the cover on your AC outlet (which should be grounded to the AC line ground). IOW, is the problem in your computer or is it before the computer, like is it in the AC line socket the computer is plugged into? Is the voltage still there if the computer is turned off? Are there any other wires connected to the computer such as to powered computer speakers?
What I trying to figure out is whether the computer is causing what you are seeing and if it is, then is at AC line ground problem or is the SMPS acting like an RF broadcast station?
Still don't know if your computer case is grounded or not? Is grounded to the AC line with a 3-wire AC line cord? Its it desktop or laptop?
What frequency is the voltage you are measuring when you are acting like an antenna with your hand on the meter lead? Is it 1MHz or is it 60Hz? IOW, is it from an SMPS or from the AC line?
Anyway, a better test would be to measure from the computer case to a cold water pipe somewhere. Also measure not just from the computer case, but also from the screw that holds the cover on your AC outlet (which should be grounded to the AC line ground). IOW, is the problem in your computer or is it before the computer, like is it in the AC line socket the computer is plugged into? Is the voltage still there if the computer is turned off? Are there any other wires connected to the computer such as to powered computer speakers?
What I trying to figure out is whether the computer is causing what you are seeing and if it is, then is at AC line ground problem or is the SMPS acting like an RF broadcast station?