I can recommend this charger for curing ground loop problems:

http://www.powersuppliesonline.co.uk/products/powerstar-laptop-pro---120w- universal-ac-adapter-/powerstar-laptop-pro/default.htm

It's build well, has good feature set and can accomodate pretty much any laptop.

Better than a DI box fudge if it's the laptop psu that's causing your problem
Gav

Thanks for the link Gav. It's certainly useful that that PSU gives a good comprehensive list of the laptop models it supports.

I've already discussed this solution in this FAQ entitled 'Curing Laptop Ground Loops with a Universal Power Supply':

www.soundonsound.com/forum/showflat.php?Cat=&Number=690190

As I say there, it's quite possible to find suitable double-insulated PSUs for around £20/$45, which may be cheaper than a quality audio DI box.

However, having such a box in your arsenal can be quite handy!


Martin

--------------------
YewTreeMagic

I didn't mean to poo poo DI boxes as they of course have their place!
CHeers

Hey,
Its really worthy.I found solution to my problem with my laptop by the information you provided.

Thank you


computer health check

Thanks for the advice Gaav. I recently bought a MOTU Ultralite to use with my Acer laptop and had the ground-loop problem. I though I had wasted my money but the PowerStar Universal adaptor has saved the day and my rig is now free of wierd noises. To anyone with this problem I can thoroughly recommend a figure-of-eight wired, double insulated psu (follow Gaav's link).
Having considered a laptop up-grade to try to fix the problem I am very happy to have spent only £40 on a psu.

!WARNING!

I bought this power supply recently and while it works great at cutting the ground loop noise(s) it makes the touch pad pointer unresponsive and slows down the mini joystick (like the one available in IBM/Lenovo/ACER laptops).

I'm very disappointed at the moment and can foresee that it will be a hassle getting a refund. We'll see.

The side effects on the touch pad are:
1. the pointer gets stuck and will not respond to the command.
2. once it 'awakes' it is very jerky in movement.
3. It sometimes double clicks on an item even though if there was no double click performed.

The side effects on the mini joystick:
1. It operates at a slower speed, but no jerky movement is observed.

The second I disconnect the power supply, all those issues disappear.

:-(

Quote Gav C:

---

I can recommend this charger for curing ground loop problems:

http://www.powersuppliesonline.co.uk/products/powerstar-laptop-pro---120w- universal-ac-adapter-/powerstar-laptop-pro/default.htm

It's build well, has good feature set and can accomodate pretty much any laptop.

Better than a DI box fudge if it's the laptop psu that's causing your problem
Gav

---

--------------------
www.electric-himalaya.com
VST and hardware synth sound design

Just googled this problem. Interesting. At first try the following suggestion as posted in the link below works. I have pasted it here as well:

http://superuser.com/questions/76649/laptop-touchpad-works-incorrect-when- on-power-supply

Quote:

---

I can confirm that my issue disappears when I do the following: - unplug the power supply from the laptop. - touch a metallic part of the laptop (i.e. USB port) - place the laptop on my lap (probably earthing it as above). - touch the power supply with my hand.

---

--------------------
www.electric-himalaya.com
VST and hardware synth sound design

By the way, I was going to mention another unforeseen problem.

This power supply has a very large power cord with an adapter. You choose the appropriate adapter for your laptop and attach it to the power cord end which goes in the power socket on your laptop. The issue I have is, together with the adapter, the whole thing is huge and it protrudes from the back of my laptop making it impossible to place the laptop in its place on my desk. Arrgh! The original power supply that came with the laptop has the end at an right angle. It is also very small, so it means I can just squeeze my laptop in the limited space on my desk. With this new power supply, I can not do that ! I'll post some pics once I get the time.

This is madness. I solve the ground loop issue with the new power supply, but can't use it on my desk since it's too big and won't fit in.



--------------------
www.electric-himalaya.com
VST and hardware synth sound design

Further to the problem with the jerky touchpad and the power supply, once I put the laptop on the table, the problem comes back. It seems that keeping it on my lap is the only way to overcome this issue. Not an optimal solution.

--------------------
www.electric-himalaya.com
VST and hardware synth sound design

Quote himalaya:

---

Further to the problem with the jerky touchpad and the power supply, once I put the laptop on the table, the problem comes back. It seems that keeping it on my lap is the only way to overcome this issue. Not an optimal solution.

---

Hi Raph!

Hmm...

Just read that thread and it ties in with my initial thoughts on reading your post - the laptop relies on having properly earthed metalwork for the capacitive touchpad to work, so when you replace the manufacturer’s PSU with a non-earthed one you run into problems until you earth it yourself by body contact with the laptop metalwork.

However, if you’re getting ground loop problems then it’s because your laptop is connected to earth by at least two electrical paths (which is why disconnecting the earth on its own PSU gets rid of the nasty noises).

With nothing earthed plugged into the laptop its chassis will ‘float’ and give you that furry feeling, so to get that touchpad working I suspect you simply need a good earth connection from somewhere else. Once the furry feeling goes, you ought to be back in business

An alternative might be to use the original PSU when working on your laptop by itself, and swap to the replacement double-insulated model when it's plugged into other earthed gear.

Fingers crossed anyway!


Martin

--------------------
YewTreeMagic

How long do laptops in a music sequencing situation last on just batteries? Also what is the largest capacity replacement battery available? Would the use of a lead acid car booster battery be an option?

I seem to remember having ground loop noise problems with my sister's laptop, while I was having a go with it; all the noise disappeared when run from the interal battery only.


NCGM

--------------------
Footloose and fancy free...gizz a job!

The problem is that for audio purposes laptops invariably give less problematic audio if they are run ‘flat out’, so although you might get four hours or more juice on typical use from a laptop battery, this might drop to under two hours when used for audio


Martin

--------------------
YewTreeMagic

I use my lappy on batteries everytime when recording audio on location.

I get 1:40 h use on average. When using the laptop with VSTs, it takes much quicker to drain the juice, obviously. One trick that helps to keep the battery going for longer is to reduce the screen brightness right down to minimum. I can use 20% of screen brightness and still work.

--------------------
www.electric-himalaya.com
VST and hardware synth sound design

Under two hours then - just what I suggested above


Martin

--------------------
YewTreeMagic

Quote Martin Walker:

---

Fingers crossed anyway!
Martin

---

Yeah! Thanks Martin. I will do more experiments ( and hopefully won't get electrified in the process, ). Luckily I can work using the mouse without any side effects. I can touch Echo Indigo's headphone output and it earths the laptop as well, getting rid of the problem. But in all honesty, all I want is for my desktop Audio PC to come back from service, it's been there almost a year!!!

--------------------
www.electric-himalaya.com
VST and hardware synth sound design

Martin,

Given all the minefields I am looking at the specialist providers. I appreciated the review of the Scan 3XS laptop a couple of months ago but was wondering if there was any chance of a review of the Rain Recording Thinkpad LiveBook? (http://rainrecording.co.uk/products/livebook/#models)

That piques my interest primarily because it basically uses the Lenovo Thinkpad and makes tweaks to it. Which suggests that the Lenovo Thinkpad isn't far away from being suitable for music in the first place.

A review would be greatly appreciated!

Many thanks

Len

--------------------
www.youtube.com/leonardngmusic

Hi Martin,

Sorry if this is an obvious question as I have read your two articles, which were very informative and eye-opening but I am somewhat of a novice in certain computer terminology:
I have a Dell Latitude D520 (mentioned in your second article as being problematic). When I unplug the PSU (to run solely off the battery power) the glitchy noises still occur in my DAW. Just to clarify, does that mean that a DI box would still help? And would this go between the guitar and interface for example? (I don't use monitors at present).

Thanks,

Will

Hi Will,

If those glitchy noises are due to a ground loop but they don’t disappear when you run your laptop on battery power then your ground loop must be elsewhere. Have you tried my step-by-step guide to tracking down ground loops yet?

www.soundonsound.com/sos/jul05/articles/qa0705_1.htm

A DI box will solve many such problems, but shouldn’t be used between a guitar and interface, since the guitar is not attached to mains earth, but relies on the earth connection from your interface - moreover, you can’t have a ground loop problem between two items of gear when one isn’t already connected to ground

However, you may have poor screening on your guitar - Andy (zenguitar) is our resident expert in that area, and will probably be along in a minute or two


Martin

--------------------
YewTreeMagic

How about an hour or two? Is that close enough?

And if you find that the noises are coming from your guitar, let us know here or in the Guitar Tech forum and we'll do our best to help you get it sorted.

Andy

--------------------
When the going gets weird, the Weird turn Pro.

Quote Martin Walker:

---

Hi Will,

If those glitchy noises are due to a ground loop but they don’t disappear when you run your laptop on battery power then your ground loop must be elsewhere. Have you tried my step-by-step guide to tracking down ground loops yet?

<a href="/sos/jul05/articles/qa0705_1.htm" target="_blank">www.soundonsound.com/sos/jul05/articles/qa0705_1.htm</a>

A DI box will solve many such problems, but shouldn’t be used between a guitar and interface, since the guitar is not attached to mains earth, but relies on the earth connection from your interface - moreover, you can’t have a ground loop problem between two items of gear when one isn’t already connected to ground

However, you may have poor screening on your guitar - Andy (zenguitar) is our resident expert in that area, and will probably be along in a minute or two


Martin

---

Thanks very much for your reply Martin, I've read the article and tried changing each component in my set-up (including 3 different guitars) but still have the exact same glitchy sounds. It's such a basic set-up though that's there's not many variables - it's just guitar > Novation Nio > laptop and I'm listening to the audio through headphones into the Nio (so no mixers/amps etc).

Just to clarify then, would a DI box's main function therefore be to isolate the inputs and outputs of the audio interface? And in terms of my basic set-up where would the DI box go? (between the Nio's output and the headphones for example?) Sorry if these are stupid questions, I'm only slightly beyond novice level on this stuff (hence trying to work on the ins and outs of eliminating noise etc)

Many thanks again

Will

Hi again Will!

The Nio is bus-powered, so the only mains earth connection is likely to be from your laptop. Since you’re listening to the Nio output directly using headphones, and have no other mains-connected gear attached, then I reckon it’s impossible for you to be suffering from a ground loop, which requires at least two connections to mains earth to complete the loop.

To answer your points, the function of a DI box is to break an existing earth loop, and with your described setup I no longer think you have one.

In fact, the thought occurs that perhaps your laptop isn’t earthed at all i.e. has a ‘figure of eight’ mains plug/socket and an oval rather than circular mains cable. If this is the case then the noises you’re hearing may simply be that NOTHING is earthed - guitars in particular can pick up all sorts of nasty interference noises unless you earth them.

Andy has arrived ready for any guitar-based advice, but in the meantime I’d try plugging in a cable to any of the laptop’s unused sockets and then touching the outer metalwork of the plug (NOT any of the pins inside the plug) at the other end of the cable to a nearby earthed object such as a radiator (find a bare metal bit). if your noises go away you need to create a more permanent earthing cable.

Good luck!


Martin

--------------------
YewTreeMagic

The ART hum remover box didn't do it for me

Made the hum worse actually

-1

Just FWIW.

I was sat with Fluke DMM and HP G6 power supply and decided to check mains earth pin to DC out neg'.

One million Ohms (1.01M actually). Is light and reason therefore begining to dawn?

Dave.

Edited by ef37a (18/09/11 06:04 AM)

Yep - that’s what my ancient Clevo laptop is like, and its metalwork also feels ‘furry’ to confirm that it’s not connected to mains earth in any way until you plug it into another earthed item such as a mixing desk or amp

No ground loop problems though


Martin

--------------------
YewTreeMagic

This topic help me to fix my problem.
Thanks guys

--------------------
Save the Marriage

Yay - another satisfied customer


Martin

--------------------
YewTreeMagic

I laughed a little bit because of the title of the topic, but it's so true! Sometimes I just get strange noises out of the boxes and I wonder why this is happening. But I'm not an expert in trouble shooting, therefore I always need help from experts, who fix it for me! Thanks for the nice recommendations in this thread.

Few months back, there was a funny noise in my laptop. I think the problem was due to earthing. As soon as a I found some hint about the problem, I change my adapter to other plug, after that the sound stops.

--------------------
Want Guitar Pickups? Get it from WDmusic.

http://www.elektor.com/news/usb-isolator-prevents-ground-loop-problems.205 2044.lynkx?utm_source=UK&utm_medium=email&utm_campaign=news

This ^ just caught my eye, have not even read up on it yet but I would make one observation.

My V old HP laptop makes a horrible noise running into a pc outputting audio from a usb AI when using the charger. I butchered a usb lead to remove the shield and that did diddly squat to cure it! Ok on battery power so deff' an earth loop.

Caveat whatsit!

Dave.

Hi Dave!

'emptor' is the word you're searching for

I suspect that USB isolator will be mighty expensive

Just checked and it's not as bad as I expected: 84 Euros + VAT

www.cesys.com/en/products/kategorie/signal-processing/produkt/usb-isolator


Martin

--------------------
YewTreeMagic

Quote Martin Walker:

---

Hi Dave!

'emptor' is the word you're searching for

I suspect that USB isolator will be mighty expensive

Just checked and it's not as bad as I expected: 84 Euros + VAT

www.cesys.com/en/products/kategorie/signal-processing/produkt/usb-isolator


Martin

---

Yes, knew that, being silly.

Expensive if it does not work! As I say I open circuited the shield on a cable and it did not cure the loop problem. Is this device more than just a "braid breaker"?

I suspect the loop is formed by the DC return and so the only way to break that would be a DC-DC converter and since such devices are only about 80% efficient this could cause problems with some AIs?

Dave.

Hi folks,

My i7 Desktop home-brew pc is makin two kinds of strange noises ... both sharing the curious problem that they are entirely uneffected by changes in soundcard / DAW volume changes. I am monitoring the sound via headphones plugged straight into my soundcard (RME AIO).

Here's the two kinds of noise :

1 > A very quiet kind of fuzzy high-freq interference that dances in time with mouse movements + computer activity. The most annoying of the two as it quietly fuzzes at me when I'm doing all those DAW things that dont involve listening to the music. Aaaargh, I can hear it now.

2 > A quiet high-pitched 'test tone' type wail added only when monitoring a live input. I am running unbalanced signals throughout (the RME card has optional balanced signal expansion that I'm considering).

The only equipment plugged into the mains at the moment is the pc, monitor and cable modem. I've rebuilt the pc at the weekend, tried different soundcards / graphics cards / power supplies and the noises remain.


I've read the thread but cant see anything quite like this described as a ground loop. Friends think I'm mad as the noises are pretty quiet but they're driving me slightly nuts, I'm a 35yr old with a history of tinnitus so should, in theory, be the last person to moan about strange persistent noises in me lug-holes.

Any advice greatly appreciated before I resort to violence!

Silentmind, you have a monitor. Does that perchance take an earthed IEC plug?

If it is powered from a line lump does the lump have a 3 core main lead and if so unpug it and check for earth continuity from mains plug earth to sleeve of the DC power plug.

You say " Wail when monitoring a live input". Input from what and is it earthed?

Never mind the proles that call you nuts! We have come a long way and paid very good money for -100dBFS noise floors (I am not quite there yet but I do get -93dBFS and no waily/buzzy noises!). You want it right!

Have you emailed RME? I would think they are helpful people (like Quad, A&H and CTH the "top people" usually are)and might have found an incompatibility with something in there? And download Right Mark analyser, that will give you a graphic picture of the problem.
BTW RM, Don't like the re-vamp. If it ain't broke!

Dave.

I hope someone can help me diagnose this problem with my desktop machine.

I am getting unwanted noise via the line in on my on-board sound card which has the output from a DJ mixer connected to it. If I am monitoring the line in and I turn my speakers up loud, I can hear a kind of ticking noise and a high frequency tone that keeps changing in pitch. This happens even if my mixer and turntables are switched off, so there's nothing going into the line in and in theory I should hear nothing but silence.

I bought an internal PCIe card thinking that this would solve the problem as I assumed that the on-board sound card was just poor, but it didn't. As soon as I clicked the button to monitor the line in, the ticking/high frequency noise can be heard when the speakers are turned up loud. The on-board sound card was disabled in the BIOS at this stage.

In both cases, as soon as I stop monitoring the line in, the speakers are silent when the volume is cranked up.

Specs of my PC: -

Maximus IV Gene-Z/Gen 3 motherboard
Intel Core i7 3770K CPU
16GB of Corsair RAM
Corsair 620HX modular PSU
Samsung 830 128GB SSD
Hitachi 2GB HDD

It's running Windows 7 Professional 64 bit with all of the latest patches/drivers/firmware/BIOS installed.

Thanks in advance!

Hi funkinlesson!

This does sound like a digital ground loop problem – the symptoms you describe are exactly what you'd expect in such a situation. However, the specs of your PC are largely irrelevant – what you need to do is follow the more general and extremely systematic 'tracking down ground loop problems' Q & A that I wrote for SOS July 2005:

www.soundonsound.com/sos/jul05/articles/qa0705_1.htm

This will determine the gear item that's the culprit, and then you can use the advice elsewhere in this thread to cure the problem.

Good luck!


Martin

--------------------
YewTreeMagic

Thanks for the reply, Martin.

I have a question - Assuming that a ground loop was the cause, would this still happen if I used an external sound card instead?

I started off by using the on-board sound and that gave me interference. I bought a couple of internal PCIe sound cards and they both suffered with the same problem. I then switched to an external USB sound card and the interference went away. Would that rule out a ground loop as being the issue, because would it not affect the external sound card if that was the cause?

Many thanks!

No, sadly it makes no difference if the audio interface is a card inside your computer or in an external enclosure.

All that matters as far as ground loops are concerned is whether two or more devices are each connected to mains earth, and then how their audio is inter-connected.

That's why a step-by-step approach to isolate the culprit(s) is the only successful way to proceed


Martin

Martin

--------------------
YewTreeMagic

Quote funkinlesson:

---

I then switched to an external USB sound card and the interference went away. Would that rule out a ground loop as being the issue...?

---

No, it just indicates that the external sound card was better designed.

Ground loops are an inherent fact of life. Most equipment employs a mains safety earth, mains socket earths are always joined together, and most audio interconnections involve an earthed screen -- so 'ground loops' will always exist.

The problem occurs when the current that inevitably flows around such loops is allowed to influence the reference ground of the audio circuitry, because it then becomes audible.

There are ways of minimising the current flowing around the loop -- such as plugging all the equipment into power strips fed in a start formation form a single wall socket -- or of breaking the loop by isolating the screen conenctions directly or via transformers. And such techniques usually render the unwanted hums and buzzes inaudible.

But fundamentally, well designed equipment using balanced connections shouldn't suffer from the problem in the first place. Sadly, there is still a lot of less than perfect equipment around.

hugh

--------------------
Technical Editor, Sound On Sound

"Click here if your desktop/laptop audio contains strange noises"

Martin, I'm probably kidding myself, but I prefer to call mine 'music'.

That of course is your prerogative Telenator - you are of course at liberty to post a link to your 'music' so that we can give you a second opinion


Martin

--------------------
YewTreeMagic