Laptop sound noise

Corbettlight

Corbettlight

Active Member
Hello,
When I have my laptop hooked into our sound board for music, effects, etc., it sounds great... Except when my laptop is charging. Is there any way I can fix this?

Thanks
 
Assuming you have no building power issues or poor cabling causing the hum, try one of these. I picked one up a couple of years ago, and it works great.

PAC SNI-1/3.5 Hum Killer Noise Filter Laptop Ipod MP3 - eBay (item 200366145511 end time Aug-22-09 10:53:38 PDT)

A more expensive but professional solution is the Whirlwind PC DI.
Whirlwind / Direct Boxes

Do swap out / check out your cabling and connections (both power and audio cables) to make sure there is nothing going on there causing it.

~Dave
 
I have heard that some laptops are particularly bad when plugged into a wall, even with a DI.

I have no personal experience with the situation, but could you get a different model of power supply for your laptop? That might solve the problem.
 
Or get a "real" audio interface such as the M-Audio FastTrack Pro ... you'll enjoy the improved sound quality as well as getting rid of the hum :)
 
I actually have an M-Audio (Pro?) Duo for home recording. Is there a way I could incorporate that into my design?

Thanks
 
Corbettlight said:
I don't have much experience with this stuff, how would go about hooking it into the system?
Click to expand...

Just hook it up to the computer via the USB ports using a regular printer-style usb cable. Hopefully your Pro came with a USB cable. If not, grab a printer cable. Then connect your outputs to your sound mixer using TRS cables (1/4" stereo jacks) to get balanced signal through. They must be TRS cables, not TS cables. The TRS jack looks like a stereo headphone jack, the TS looks like a mono jack.

Look at pages 4 and 5 in the manual:
P4, item 6: leave standalone switch in the OUT position
P5, item 2: connect via USB to your laptop
P5, item 4: use TRS cables to connect to input channels on your mixing board.
P5, item 5: leave Line Level switch in OUT position for +4dBu

You will also need to install the M-Audio software on your laptop. Once you do, a Control Panel should become available that let's you configure the M-Audio (which you shouldn't have to adjust from factory settings), but more importantly, the M-Audio will now show up as an output device option from your Windows programs.

Let us know how it goes.
 
The solution jkowtko proposes is probably your best option. If you can't get that to work, the best options that I came up with are the use of an external sound card (connected via USB) or a sound filter like what has been mentioned or this one by D'san which is specifically for this purpose. I find that the laptops that have a grounded power supply are usually the biggest culprit of this type of noise.
 
g15 said:
one of these
Ground Lift Adapter. Cooper 419GY

We have a dell laptop that makes the most horrible noises if it's plugged in and grounded. We ended up pulling the ground prong out and now it works great.
Click to expand...

DO NOT EVER USE THESE.

You defeat the purpose of the Earthing system. As I understand your convoluted electrical system, the purpose of these is that the lug gets bolted to the GPO case to provide the ground connection. Lift the ground and YOU could become the path to Earth under fault conditions...
 
Not that I'm advocating using ground lifts, but doesn't the risk with AC adapters stop at the transformer (there's only a two-conductor, low voltage cord to the laptop itself) So, theoretically, if you keep the transformer wrapped up and close to the power outlet then your risk of electric shock is very localized.

This is of course different from rack mounted gear with three-conductor power cords running from the rack ...
 
jkowtko said:
Not that I'm advocating using ground lifts, but doesn't the risk with AC adapters stop at the transformer (there's only a two-conductor, low voltage cord to the laptop itself) So, theoretically, if you keep the transformer wrapped up and close to the power outlet then your risk of electric shock is very localized.

This is of course different from rack mounted gear with three-conductor power cords running from the rack ...
Click to expand...

My laptop has a 3 pin clover leaf connector on the power supply. Just having got the meter out, the DC connector has it's outer grounded. It's a Dell and actually using a tricentric connectors with centre pin and then inside and outside of the shell.

Basically if it has a ground connection on the device, I would assume that grounding is necessary for the safe and optimal functioning of the device...
 
g15 said:
one of these
Ground Lift Adapter. Cooper 419GY

We have a dell laptop that makes the most horrible noises if it's plugged in and grounded. We ended up pulling the ground prong out and now it works great.
Click to expand...
Please read the description in the link you referenced, you apparently are not using that adapter for the intended purpose. Adapters like those are intended to adapt modern three prong equipment that relies on a dedicated safety ground to older two conductor electrical system that used the boxes and conduit for the safety ground path. The metal tab connects to the center screw on the plate which via the metal face plate, box and conduit provides the safety ground path. Basically, those adapters are meant to provide a continuous safety ground path when using newer devices with older electrical distribution systems and not to break the ground path. Using them to do so is not only improper use of the device but also a code violation and dangerous.

jkowtko said:
Not that I'm advocating using ground lifts, but doesn't the risk with AC adapters stop at the transformer (there's only a two-conductor, low voltage cord to the laptop itself) So, theoretically, if you keep the transformer wrapped up and close to the power outlet then your risk of electric shock is very localized.
Click to expand...
In normal use, but not in the event of a failure, which is where the safety ground path may be critical. Imagine if the transformer failed in some way, without a safety ground where does that current go?

Devices with two prong plugs are usually Class 2 or 'double insulated' rated. [FONT=Verdana, Arial, Helvetica, sans-serif]This means that the devices are designed specifically to not require a safety ground and are instead[/FONT][FONT=Verdana, Arial, Helvetica, sans-serif] required to prevent exposure to dangerous voltage or current from any failure without the use of a grounded metal casing. [/FONT][FONT=Verdana, Arial, Helvetica, sans-serif]There are also strict requirements on the insulation resistance and leakage to any ground or signal connections. Double insulated devices do not, and should not, have a separate safety ground connection. However, any devices with a three prong plug or safety ground terminal should be assumed to potentially fail in a manner that could represent a shock hazard and thus they require a safety ground connection.[/FONT]
 
Make sure you are using the correct Dell power supply. There are 2 prong on the AC side and 3 prong on the AC side Dell power supplies and they are different though both will power the laptop. If you mix them, specifically using the 3 prong on a laptop that is expecting the be used with a 2 prong you will get hum and nasty noise on the laptop. It sounds like you may not have the right power supply, or a further power issue with your set-up.
 
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