[JonathanHF]

Recently I found that there were a lot of noise coming from my PC speakers,
and guitar amp. It makes high pitched, and bug like sound every second.
Later I found that the noise is caused by my Toshiba laptop.
The noise appears when the power is supplied by AC, and disappears when
the laptop is ran on battery. I'm certain the problem is not caused by the ground loop because, first, the cheater plug does not reduce the noise, second, the noise is not the low pitched sound the happens when there're ground loop issues.
From my research the noise is caused by the poor quality of the power supply as those manufacturers have been costing down everything these days.
I cannot really blame on Toshiba since other companies like HP, Dell, and Lenovo all have this issue.
I've done a lot of research in the past few days just to find a solution, but can't seem to find a solid solution to the problem.
I heard the isolation transformers will work but they are too expensive, and I have no past experiences with those.
Please help me with this problem as this has taken away my sleep for the past few days.

 

[ROBSCIX]

What happens when you have the devices on different outlets that are not on the same circuit?

 

[dexter3d]

Try to feed your laptop with linear lab power supply. IMHO the problem in your case is the crappy SMPS. I experimented with dedicated audio pc's, and feeding them (even partially) with linear PSU's REALLY helps to decrease the noise floor to unnoticeable levels. This is valid even with expensive 'pro' grade sound cards which are supposed to have good filtering and so on..

 

[parskey]

you could get and eliminate it by placing a optical step somewhere along the line.

 

[JonathanHF]

Quote:

Originally Posted by ROBSCIX /img/forum/go_quote.gif What happens when you have the devices on different outlets that are not on the same circuit?

The noise is still there and loud.
I have my guitar amp and laptop plug into different power outlets on completely opposite walls.
So the crappy laptop power affects my whole system as long as I plug the power in.

Quote:

Originally Posted by dexter3d /img/forum/go_quote.gif Try to feed your laptop with linear lab power supply. IMHO the problem in your case is the crappy SMPS. I experimented with dedicated audio pc's, and feeding them (even partially) with linear PSU's REALLY helps to decrease the noise floor to unnoticeable levels. This is valid even with expensive 'pro' grade sound cards which are supposed to have good filtering and so on..

Though it seems to be a great solution, the Linear Lab Power Supply is too big for my room(I live in a dorm). And the price is a bit over my budget.
I'm thinking if there is something to filter the noise or prevent the noise from my laptop's power supply.

Quote:

Originally Posted by parskey /img/forum/go_quote.gif you could get and eliminate it by placing a optical step somewhere along the line.

which line are you refering?
I don't think your a optical step will work as the interference comes from my crappy laptop power supply.

 

[Mad Max]

Power filter?

 

[dexter3d]

Quote:

Originally Posted by JonathanHF /img/forum/go_quote.gif The noise is still there and Though it seems to be a great solution, the Linear Lab Power Supply is too big for my room(I live in a dorm). And the price is a bit over my budget. I'm thinking if there is something to filter the noise or prevent the noise from my laptop's power supply.

hmm, mine is just slightly bigger than a standard PC power supply, and cost like 60 Eur new

I think the best solution for you would be to get an external DAC with a separate PSU.

 

[JonathanHF]

The one I found cost 150USD.
I have an external audio interface, so the interference from my laptop isn't a problem.
I think it is my laptop's power supply that introduces nosies to the whole power outets. Even when all the connection's are removed, except for the power of my speaker, it still make nosies because the power supply from my laptop is polluting the power.
When I get my ear close to the DC brick, I heard exactly same high pitched noise that comes from my speakers. Except my speaker amplifies the signal to a intolerable volume.
Would you post a link of the kind of PSU you referred to?

 

[terriblepaulz]

I had the same problem, and observed the same difference when running my laptop on battery vs AC. The problem existed when I had a direct usb connection to my dac (regardless of whether I had usb selected). I use a cheapo usb to optical converter and do not use the usb input of my dac unless I am going battery power. Problem solved (at least for me).

 

[dexter3d]

Quote:

Originally Posted by JonathanHF /img/forum/go_quote.gif The one I found cost 150USD. I have an external audio interface, so the interference from my laptop isn't a problem. I think it is my laptop's power supply that introduces nosies to the whole power outets. Even when all the connection's are removed, except for the power of my speaker, it still make nosies because the power supply from my laptop is polluting the power. When I get my ear close to the DC brick, I heard exactly same high pitched noise that comes from my speakers. Except my speaker amplifies the signal to a intolerable volume. Would you post a link of the kind of PSU you referred to?

Mine is like this:
ToolsOnlineShop : PS1503SB - LABORATORIUMVOEDING 0-15V / 3A DIGITALE DISPLAY MET ACHTERGRONDV

What is the source of power for your external interface? Is it the laptop (power via USB)? You should get a DAC with autonomous power, problem would be solved.. there are many options to choose from. Or, cut the USB cable, and feed your external interface with a clean 5V source

 

[haloxt]

If you were using a pc I'd recommend a $40 earthwatts psu, but since it's a laptop I suggest furman ac-215 power conditioner, sometimes you can get one used on ebay for $75 shipped. It's designed specifically for video/audio and impede current less than conditioners not meant for audio, so can even try plugging the guitar amp to it.