Laptop PSU started to create ground loop?. Will galvanic isolator help?

[Wendigo79]

I just rearranged my desk and hifi kit near it. Then out of nothing, buzzing and hum appeared on my speakers. I have a Sony Vaio laptop that is connected to a Topping E30 DAC. If i unplug the usb, noise disappears. If i unplug the PSU from laptop and run it by battery, noise disappears. So i think that the problem comes from the laptop PSU. Laptop, amplifier and DAC are all connected to the same power source. Would a galvanic isolator remove the noise? I mean a galvanic isolator that would be located on that usb-outlet that feeds data for DAC. The DAC gets it's power from separate wallwart. I find it odd that the noise started after i rearranged everything. The power source is still the same though. Could my laptop psu be dying? When i squeeze the psu, noise intensifies and tones down in turns. Also touching and turning the psu changes the noise. Perhaps something has gotten loose inside the psu? Unfortunately the psu is type that cannot be opened. I didn't knock it anywhere when rearranging my kit. The problem just started suddenly. Tried to change wallsockets for the laptop and for the dac. No help from that. So I started to think that would galvanic isolator do the trick?

 

[Wendigo79]

Found that if I wrap the power cord around the psu, the noise gets reduced. So something to do with an em-field. Also that explains why touching the psu can change noise levels. Also found that cheap isolators from aliexpress won´t support data speeds higher than 12mbs. So those isolators won´t allow 24bit 96khz traffic to my dac. So will have to live with this. And buy another pc someday. Wrapping the power cord provides help until that

 

[NTomokawa]

Is your laptop PSU a stock one? Or a no-name aftermarket one?

 

[Wendigo79]

It´s an original psu

 

[NTomokawa]

Check out this thread: https://www.audiosciencereview.com/...s/laptop-source-cheap-bad-power-supply.10401/

Looks like an isolation transformer would indeed work to resolve this issue.

 

[Wendigo79]

Tried to debug more and found following. When I unplug the psu from socket the noise stops. Also when I unplug the USB-cable that connects the laptop to the DAC, the noise stops. So I am thinking that could it be on the low power side of the system? I mean that if the problem would be on the mains side of the laptop charger, then the interference would travel from the PSU to the null wire and then spread to other devices from there. But if it is on the 19.5V side of the charger, then it would travel from there to the ground of the laptop, and from there to the USB-outlet? So if I get an 230V isolation transformer for the mains side of the PSU, it wouldn´t help? Well, I am going to buy today that kind of ferrite snap on thing (don´t remember what they were callen on in English) for power cable of the PSU. If that reduces noise, then I guess isolation transformer would solve it? I also try that ferrite thing on the 19.5V side on the PSU. If that helps then i guess the problem is on that side then?

 

[Wendigo79]

Decided to make a bit more testing and found following. I connected my headphone amp to the DAC instead of the amp I normally use with it. The headphone amp has a real old school transformer (Topping l30). And I turned the volume to max. And it was dead silent. So because the old school transformer creates galvanic isolation the interference disappeared? So perhaps an isolation tranformer for the laptop charger would make exactly the same thing? Will still test those ferrite things today. (edit. The Pioneer amp has also big toroidial transformer...)

 

[DDF]

If the laptop psu is grounded (3 prong), try changing it to class 2 (2 prong). Worked for me with exact same symptoms

 

[Orak]

Had the same problem with my E30 had a residual background noise regardless of what power supply i tried even batteries sent it back for refund with Amazon, from my experience i believe its a design fault.

 

[Wendigo79]

Had the same problem with my E30 had a residual background noise regardless of what power supply i tried even batteries sent it back for refund with Amazon, from my experience i believe its a design fault.

Mine works silently when using optical. So it has to be about my laptop and usb

 

[Katji]

I wonder why it began after you rearranged things.

Found that if I wrap the power cord around the psu, the noise gets reduced. So something to do with an em-field. Also that explains why touching the psu can change noise levels.

Maybe moving it brought up a problem with the PSU wire?

 

[Wendigo79]

Got myself a ferrite ring and added it to the power cable. No effect. So i must get either a new psu with two pins or an isolation transformer. I think that the isolation transformer is the best option. I future I will anyways get a new laptop and the problem may come back. So an isolation transformer is the most future proof solution.

 

[Wendigo79]

I wonder why it began after you rearranged things.



Maybe moving it brought up a problem with the PSU wire?

I started to use this Pioneer amp about the same time when i rearranged things. That was actually the reason why i rearranged. Before that i used that Topping l30 headphone amp. I didn´t first realise that when i posted first message about this.

 

[DDF]

Got myself a ferrite ring and added it to the power cable. No effect. So i must get either a new psu with two pins or an isolation transformer. I think that the isolation transformer is the best option. I future I will anyways get a new laptop and the problem may come back. So an isolation transformer is the most future proof solution.

A quality mains isolation transformer costs many times a class 2 aftermarket brick, and also adds loss and limits power draw. A class 2 supply is readily available, much cheaper, without these trade offs

 

[Wendigo79]

A quality mains isolation transformer costs many times a class 2 aftermarket brick, and also adds loss and limits power draw. A class 2 supply is readily available, much cheaper, without these trade offs

Well yeah, you might be right. Small isolation transformer is about 110€-130€. And those class 2 power supplies come with many different heads, so they can be used with different laptops in future. So i guess I will go that road next. Thanks for advice everyone!