Laptop earth-buzz audio fix

[lecnoob]

Ok - long story short. I do music shows and have power trouble using laptops for audio - earth buzz issues. My usual fix has been to find a replacement power supply designed with no earth pin on the plug - no more buzz. This has worked for the last few Toshiba laptops I had and is way cheaper than messing around with earth-loop killers or whatever.

So, my new Samsung has the usual problem, but now I can't find a 2-pin replacement power supply. I've been warned off just disconnecting the earth on the OEM power supply as apparently it might need it by design - though I have no idea why it should do when a 2-pin power supply works totally fine. Please correct me if I can just do this!

In desperation then I'm considering just swapping the tip over on my old Toshiba replacement 2-pin supply and using it with the Samsung - it's 19V and has enough amps. Is this a dumb idea? If not, can anyone tell me where I can buy a solder-able DC tip?

Many thanks!

(Tried posting this here first but doesn't seem like anyone there knows)​

 

[trev]

Sorry for being blunt here but if you think that it's perfectly fine to disconnect an earth in an extension lead to rectify this problem then you should not be allowed anywhere near an electricity supply. As has been said above it's there for a very good reason and all the labels in the world will not protect you from a manslaughter charge.
Just how much current do you think it will take to kill someone?

 

[lecnoob]

Ok thanks all, will avoid cutting that earth connection!

Does this mean that UK DJ's touring Europe are in constant danger of death from their now unearthed 3-pin laptop power supplies?

 

[CrazyScozzese]

Ok thanks all, will avoid cutting that earth connection!

Does this mean that UK DJ's touring Europe are in constant danger of death from their now unearthed 3-pin laptop power supplies?

No, to clarify, what they/we are referring to is disconnecting the earth in the extension lead. That is a no-no. Besides, a lot of europe does have earthed poles in the sockets, and you should use the adapter to suit.

It is more complex than what we have discussed as it relates to the Class of equipment too. And yes, some kit such as adapters will survive with no earth, but no-one will recommend it as teh user may not be so lucky.

I would buy a second ac/dc adapter, or an opto iso. Cheap, no risk, and it works. Have a look on DV247.

I presume you don't get noise when on battery only?

 

[cymroaur]

I've had the same problem in the past, where it hummed when connected to the mains, but was clean when running on the battery. So I bought an external sound card with USB connection - problem solved! It also meant that I could use proper audio connectors instead of some poxy 3.5mm thingy!

 

[lecnoob]

As I mentioned earlier, I'm using an external USB soundcard - makes no difference. Just out of interest, what card did you get?

 

[cymroaur]

As I mentioned earlier, I'm using an external USB soundcard - makes no difference. Just out of interest, what card did you get?

Sorry, I missed that! I can't remember the card... It might have been M-Audio. The other option would be to put the audio through a DI box and earth lift it, or an audio transformer.

Out of interest, are all the equipment being fed on the same mains circuit?

 

[lecnoob]

Happens in various venues / rehearsal studios. Card is also an M-Audio, 'Fast Track Pro Ultra'

 

[cymroaur]

If you're going to cut any earths, do it on the audio! Put a DI or transformer on the laptop, it should sort it. Good luck!

 

[DNS1]

We use a Denon DJ controller with built in audio. Constant hum for us...

Not tried using DIs, seeing as:

I'd need 4 of them
I'd need 4 batteries
I'd need to convert from RCA to jack/XLR, then back to RCA after the DI for the DJ mixer

 

[cymroaur]

We use a Denon DJ controller with built in audio. Constant hum for us...

Not tried using DIs, seeing as:

I'd need 4 of them
I'd need 4 batteries
I'd need to convert from RCA to jack/XLR, then back to RCA after the DI for the DJ mixer

I admit this is a bit pricey, but there are other models around: AV-HK1 “HUM KILLER” Stereo Audio Isolation Transformer ‐ Dual RCA inputs and outputs

 

[Mr.Si]

I have tried lifting the earth on DI boxes before in my Live Sound engineering days but 1. It's not always safe to do so. 2. It doesn't always work.

My solution was to disconnect it from the mains and just run it on a battery. It usually was with Dell or HP Laptops. My "HiGrade" laptop, ran on Doubly Insulated Fig8 cable and so didn't need an earth. As such I never had the problem.

If you are concerned about the prices, then you can always get a rack-mountable 4-way or DI Box. A Behringer unit should be fine. Obviously BSS or Nomad DI boxes would be much nicer but they cost well over a ton I think.

Ebay will probably have some. Try it with active DIs rather than passive DIs.

Si

 

[lecnoob]

Interested to hear about your HiGrade laptop - was that the audio or electrical cable?

DNS1 - it's all about the power input IMHO - I'm 99% sure once I've got my 2-prong no-earth replacement power supply working I'll have no hum -- again! Its worked with every laptop I've owned.

 

[Davisonp]

Hi,

I do lots of sound and video, and the simple solution to earth related buzzes is to unplug the laptop while it is producing sound. The second solution that I have found works is a USB sound card. I have a “Trust” USB sound card with line level out that cost £15, and I have yet to have a problem with that, probably because laptop produces a regulated 5 volt supply. Lastly, a regulated laptop power supply should solve the problem as unregulated supplies can add abuzz into the sound equipment, but regulated power supplies they are more expensive solution than USB sound cards.

 

[lecnoob]

Thought all laptop power supplies were 'regulated'? Or is there some special place to get em?

 

[bill01803]

Ground loop problem

The solution is to us a DI box such as Behringer DI20 Ultra-DI Box at Gear4Music.com it is an isolation transformer, thus removing the ground loop