Noise goes away when I unplug my laptop during recording

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Hi!

For our podcast recordings, we typically use Skype as the transport. My Dell Precision 5510 laptop is the hardware platform, with a Heil PR 40 mic going into a Mackie ProFX8 for my voice and the laptop audio going into the mixer through a mini jack to 1/4 inch splitter. The main outs from the mixer go to a Zoom H6 for recording.

Generally the sound is good but the thing that drives me a bit batty is that there's a hiss noise that I only know one way to get rid of: unplug the laptop. Poof.

Some sources seem to indicate it's a known motherboard issue (I'm not likely to send it in for replacement).

Thoughts? Recommendations? Thank you!
 
https://www.amazon.co.uk/AV-Link-Gr...coding=UTF8&psc=1&refRID=M9F3AAMD7HG1B53WQ50K

Connect between laptop out jack and mixer. The H/P out is at a low enough impedance to drive such a transformer. Not "hi fi" at that price of course but good enough for Skyping I would aver? I have had a couple and they are not at all bad so long as you keep the level under a volt or so.

Of course, if it fixes the noise you can always buy better from Art or Jensen.

Dave.
 
Whenever you get this, you always discover it's a Dell. I've had two that did this VERY badly. Even worse, you cannot use alternative power supplies because the damn things notice! One thing that can work is wiring the output to two XLRs, wired sleeve to both pin 3's, and the two audio lines to the pin 2 of both plugs. This (and success depends on the preamp design for total silence) can produce workable results. If you stick a sensitive meter between computer ground and real ground, there can be surprisingly high circulating currents.
 
Whenever you get this, you always discover it's a Dell. I've had two that did this VERY badly. Even worse, you cannot use alternative power supplies because the damn things notice! One thing that can work is wiring the output to two XLRs, wired sleeve to both pin 3's, and the two audio lines to the pin 2 of both plugs. This (and success depends on the preamp design for total silence) can produce workable results. If you stick a sensitive meter between computer ground and real ground, there can be surprisingly high circulating currents.

So you are saying Rob that OP has a hum loop and the Dell takes the mains earth through to the negative, chassis, connection on the laptop?

If so, my cheap'ass traff unit will fix that. I am obliged Rob BTW! I am presently looking for a refurbed W10 laptop, just for internet and "office" duties for whan I turn my W7 machines off line. I don't really need audio capability on the W10 PC but good to know to avoid Dell!

Dave.
 
Taking a punt...The Mackie ProFX8 is mains powered?

If so, I've experienced a similar thing in the past.
The issue, at that time, was that the laptop power supply was completely isolated from the earth in the household wiring, by design, and, as it turns out, was floating a volt or so above.
The mixer, however, has its chassis tied directly to mains earth. (UK Mains - 3 pins)
There mustn't have been a direct path between the laptop chassis and the mixer chassis, and that difference caused hum/buzz.

I tested the theory by taking a guitar lead and touching one tip to exposed external metal on the laptop chassis, and the other to exposed external metal on the mixer.

If you have a multimeter you could set it to read DC voltage and take a reading between laptop chassis and mixer chassis.
Finding exposed metal on a laptop might be trickier these days?
 
Thank you so much for the responses! Very much appreciated. I'm going to try a ground loop isolator. Once again, I appreciate your advice.
 
Thanks for the heads-up about the Ebtech Hum X.

While looking at that on Amazon, I saw this in the reviews:

"I have a 12" Harbinger P.A. speaker thats plugged in the wall. My laptop is plugged into a power strip. When I connect the auxillary cable from the speaker into my laptop, there is a constant annoying HUM. When I unplug my laptop and run it off the battery, the HUM disappears. Anyhow, I was gonna buy something like this that I was told solved the problem, a Furman M-8X2 Power Conditioner, $65 from Guitar Center. The salemen ask what if I needed help, I stated my issue. He said that Conditioner wasn't gonna solve my problem and told me to buy a $1 3-prong to a 2-prong adapter for my laptop plug. Sure even it solved my issue and I called him to thank him profusely!! Case Closed!!"

Does this make sense technically?
 
The cheap adapter will get rid of the hum but, based on what I've read here and there, running a laptop without a ground pin is ill advised from a safety point of view.
 
It depends on the design of the switch mode PSU. Introducing circulating currents as a result of poor design in a PSU where the - supply is connected to mains ground/earth is problematic, and of course lifting the ground when the ground is a safety feature is stupid. Most however are class II devices and don't actually need a ground. these leave the chassis and grounds of the ins and outs floating. Connecting these to ground via typically the audio connector can introduce the hum - the reverse of the usual 'solution'. Breaking the circuit with transformers is the most suitable solution, but the devices are not that commonly found. I don't believe the Dell phenomena has been really solved. these don't seem to just introduce hum, via grounds at different potentials, but actual noise superimposed on the line, triggered by the ground differential. people have tried isolation, direct grounding and all things in between, but Dell PSUs seem to generate the worst possible combination when you want clean audio. I note that Dells also seem to have the ability to identify the model and brand of the PSU, preventing users buying cheaper off the shelf ones. You plug them in and can power the computer fine - but the computer refuses to allow the battery to charge. I cannot prove it, but I assume this could be part of the problem. Clearly some communication takes place to allow ID - and maybe this induces the noise? I really don't know.
 
Thank you Rob, my next laptop definitely WON'T be a Dell!

I have an HP and have run two Lenovos, none of those machines gave me any noise problems so I shall stick with those. I have read good reports of the Asus laptops but not in regard to audio use.

Now that you have explained the problem in more detail I am going to ask about Dells over at soundonsound.com. Will keep you all posted.

Dave.
 
I don't know about which Dells have these issues, and/or is just limited to laptops...but I've been using Dell towers for my DAW systems for the last 20 years...and never had any noise issues due to it being a Dell.
TBH...I don't much recommend laptops for DAW use, regardless of brand...but I know these days that seems to be the norm for most people.

That said...I do use Dell laptops exclusively for my other computer needs, though they don't involve audio interfaces, so I can't speak about audio noise...but otherwise, I've not had any of the issues that many Dell haters speak of. :D

Oh...and we had some Lenovo tablets at my day gig...they were an odd item one year, because otherwise Dell was/is the major computer supplier at the day gig...I mean, like 10k computers/year...but anyway, those Lenovo tables were absolute dogs, everyone hated them, and wanted to get rid of them.
So go figure... :)
 
I don't know about which Dells have these issues, and/or is just limited to laptops...but I've been using Dell towers for my DAW systems for the last 20 years...and never had any noise issues due to it being a Dell.
TBH...I don't much recommend laptops for DAW use, regardless of brand...but I know these days that seems to be the norm for most people.

That said...I do use Dell laptops exclusively for my other computer needs, though they don't involve audio interfaces, so I can't speak about audio noise...but otherwise, I've not had any of the issues that many Dell haters speak of. :D

Oh...and we had some Lenovo tablets at my day gig...they were an odd item one year, because otherwise Dell was/is the major computer supplier at the day gig...I mean, like 10k computers/year...but anyway, those Lenovo tables were absolute dogs, everyone hated them, and wanted to get rid of them.
So go figure... :)

'Twas ever so. Not that many years ago the forums were alive with people asking for laptop reccy's but the cognoscenti were at pains to point out that "whilst LAST year's HP or Dell was fine with Fwire and gave low latency there is no reason to suggest that THIS year's model will be so accommodating!"

AFAIK the very last thing laptop makers consider when developing a MOBO is the way it handles audio and if the embedded FW chip was NOT suited to YOUR AI tough tittes.

So I am not surprised at all to learn that "not all Dells are noisy". I also agree that the laptop per se is not THE best vehicle for "serious" music making and subsequent processing...But peeps LIKE handy!

Whatever the situation, I have learned from a well respected poster (even if he is "Essex man"!) that a Dell MIGHT cause me a problem. I have a choice so I shall not take the chance.

Dave.
 
Might be good to get confirmation of a cause and solution, from the OP, before we all gather outside Dell HQ with our pitchforks.
Just a thought.
 
Theatre sound folk in the UK have had the Dell issue as the most annoying make. I have three dell systems that work fine, but have had a number of dell laptops all with the noise issue. I'm convinced it's the clever power supply, because the old one I still have is noise free on a general PSU, but it won't charge the batteries!
 
"A bad workman blames his tools."

That ^ is just a saying put about by cheap ass bosses that won't stump up for proper kit!

Dave.
 
What can I say - my own experience of laptops that hum when connected to PA and recording systems is that Dell has the worst record. Hear a hum, ask the make and 9 times out of 10 it's a Dell. if you have a quiet one, do not sell it!
 
What can I say - my own experience of laptops that hum when connected to PA and recording systems is that Dell has the worst record. Hear a hum, ask the make and 9 times out of 10 it's a Dell. if you have a quiet one, do not sell it!

Thank you Rob. I did not wish to bandy your name about and get you dragged into the tiny cow! I have had similar comment from people at SoS. Nor everyone by anymeans has had hum problems with Dells but a couple have.

The Internet is of course a wonderful resource but if you search for data on ANY piece of gear, no mattter how superb or costly, somebody, somewhere will have a beef!

I base my judgements of equipment on personal evidence where I can and have bought cheap bits of kit to test. Where that is not possible (I am NOT going to drop £300-400 on anything "just to see"!!) I trust the long serving members of HR and SoS and anything that comes up on'web is checked through those.

I hope this clears the matter up once and for all.

Dave.
 
It's fine - when you have a bit of kit that works for you, obviously your opinion is shaped by that one. The daft thing is that that nobody complains because desktops hum less than portables with nasty PSUs. My own reduce it trick is to wire the laptops up to an XLR connected pins 2 and 3, with no ground connection and take advantage of the differential amp in the preamp. This can often reduce the noise to something that can be coped with.
 
Ground loops

The cheap adapter will get rid of the hum but, based on what I've read here and there, running a laptop without a ground pin is ill advised from a safety point of view.

Then how about powering all your recording gear, including the laptop, to the same power source. What you're trying to do here is avoid ground loops. It's not that hard.
 
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