Since so many new posters on this forum seem to be suffering from 'funny background noises' in their laptop audio, here's a direct link to my two FAQs on the subject to hopefully save us pointing newcomers there by hand

The first describes the probable cause of most problems, and suggests a couple of possible solutions (and one to avoid):

www.soundonsound.com/forum/showflat.php?Cat=&Number=317&page=2& ;view=collapsed&sb=5&o=&fpart=1#317

The second discusses some specific laptop models that seem to cause problems due to a grounded power supply:

www.soundonsound.com/forum/showflat.php?Cat=&Number=318&page=2& ;view=collapsed&sb=5&o=&fpart=1#318

There are lots of other FAQs as well - the full list can be found by following the link from our main forum page, or by clicking on the other sticky thread next to this one.


N.B. 02/09/2011 I've just added desktop to the title because so many desktop computer users are now suffering from similar problems. Ignore laptop-only advice relating to power supplies (all desktop PCs MUST be mains earthed), but the advice relating to tracing and eradicating ground loops is identical for both desktop and laptop computers.


Martin

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

oh thank you!!! New Tascam VLX5 monitors for Christmas but what a racket...I sorted all my cabling out and taped the plugboards to crossbars under tables and gave it all a good clean, got rid of the HiFi amp and speakers that had been on monitoring duties previously and connected up the Tascams - oodles of mains hum. Laptop is an Acer Travelmate 291LCi and yes it has a 3 pronged mains lead. If I remove its Earth connection and if this cures the noise is it safe to leave like that? The case is plastic mostly so I guess it's OK. Any advice would be gratefully received.
Trevor

--------------------
All the gear and no idea...that's me

You would probably have been best posting that under it's on thread, however my advice is NEVER remove the earth of a powersupply - it's there for a reason,

Borrow a DI box to go from the output of your laptop to monitors and ground lift it - you'll be surprised it works

--------------------
David Lewthwaite, www.lewty.org.uk, dave@lewty.org.uk

Cheers & thanks for the reply. Could I pick your brains further please? I've disconnected the Earth lead in the laptop mains plug and the problem has gone, therefore it was a ground loop. BUT as you say, this was there for a reason BUT...surely..
1. The laptop is Earthed via the other equipment as that's why I got hum in the first place
2. The 3.5 mA at 19V from the supply is hardly life threatening although a lack of Earth could cause a static build up.
3. The difficulty is whenever the Tascam interface is unplugged from the laptop then the laptop becomes un-Earthed which I could cure by buying a spare power lead with the Earth still connected for these (rare) occasions.
4. The only place a DI box could go is between Tascam interface (unbalanced RCA Phonos) and monitors (Balanced XLR or unbalanced 1/4"). Therefore wouldn't the ground lift merely stop the signal as there would only be one connection?
Please forgive me if I'm being dim...
Trevor

--------------------
All the gear and no idea...that's me

My laptop has a cheap and nasty creative MP3+ soundcard - unblanced phonos output

The DI balances the input onto XLRs and then ground lifts it - removing the ground connection in an unbalanced cable won't result in you losing the signal.

Borrow a DI from a friend and give it a whirl

Alternatively the Behringer DI20 which my laptop is flightcased with is only around £20

And you say you have an Acer Travelmate - are you sure its 3.5mA it draws on the output side of the PSU? My Travelmate draws 3.95A at 19V - which could actually kill you,

Finally, if somthing goes wrong with your laptop and power gets shorted to earth, it will find an earth path - through your audio interface and other connected equipment if need be.

--------------------
David Lewthwaite, www.lewty.org.uk, dave@lewty.org.uk

Edited by dave-lew99 (27/12/05 12:12 PM)

Thanks David, You're right, 3420 mA is 3.42A which is a whole different kettle of shocks (I must try reading things properly) What I'll do is exactly what you suggest and borrow a DI box and give it a whirl. Mind you if they're only £20 I might just buy one anyway.
Thanks for your help
Trevor

--------------------
All the gear and no idea...that's me

More from me I'm afraid...have just ordered a DI20 from Dolphin music for £20 so I can try it out. Watch this space ( and anybody else who's having the same problem) and I'll post the results asap
Happy new year
Trevor

--------------------
All the gear and no idea...that's me

Thats good, it should work - did perfectly for me, it enabled me to use my laptop live which is what i wanted it for in the first place!

And even if it doesn't a DI box is a handy thing to have knocking about, the only thing to watch out for is it doesn't have a mains adaptor, battery or phantom only.

But if you do what i did and get a 9V PSU from maplin or somewhere and just bodge it in it'll work fine

--------------------
David Lewthwaite, www.lewty.org.uk, dave@lewty.org.uk

David...guess what, DI box arrived, plugged it all in using a new (earthed) mains cable for the laptop, switched on and loads of noise....then I switched the ground lift switch and SILENCE (apart from the music of course). So thank you, have a beer you've deserved it. Anyone else with this problem ? Buy a DI box for £20 and there it is solved. I am going to sort out a 9V power supply, I've got loads kicking about and just need the pp3 connector which I'll steal from something or other. This set up also means I've got proper balanced XLRs going to my monitors which I like too.

Cheers and thanks again for your time
Trevor Gronow

--------------------
All the gear and no idea...that's me

No problem, i was forced to find a solution to it when i wanted to gig with my laptop as a keyboard sound module

Now its all prettily flight cased up with xlrs on the side, soundcard, di box psu etc in the bottom - i no longer get that look from whoever is engineering of "oh no, not another one" when i ask for an xlr and iec lead!

I was gigging once where there were quite a few bands on and one of them was doing what i do but had a laptop balanced on a bar stool, soundcard dangling off the side, mess of wires, it crackled had hum - was unbalanced, the engineer had to find a DI for them....unprofessional!

--------------------
David Lewthwaite, www.lewty.org.uk, dave@lewty.org.uk

Glad you got your problem sorted Trevor, and thanks to David for guiding you through the process!

As I said in those FAQs, a DI box will nearly always do the trick, and as you've found, it needn't be expensive either.

The problem with removing the earth connection on your laptop PSU is that in the event of a faulty PSU it's theoretically possible for mains voltage to appear on your laptop's metalwork (case, sockets, and so on), which could certainly prove lethal.


Martin

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

Thanks Martin for the reply. The laptop PSU is now safely earthed again and my system is lovely and quiet ...well until I start making a row anyway.
Cheers and thanks to SOS
Trevor Gronow

--------------------
All the gear and no idea...that's me

In addition to the above two links to FAQs on this forum, I also wrote a more general and extremely systematic 'tracking down ground loop problems' Q & A for SOS July 2005 that may help those with larger setups, and of course those without laptops:

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


Martin

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

I bought a lovely laptop over Xmas and finally got around to installing all my software on it and using it strictly as a music PC.

The laptop is a HP ZD8000 btw

I have the following gear:

Spirit Folio Mixer -> Laptop (Indigo IO input) - > Stereo Amp

with all my keyboards going into the mixer..

However I have a huge problem of noise... I'm not meaning hiss, I mean really horrible grinding/quantization style noise thats half as loud as the music I'm making...

If I just have my Promega 3 (balanced outputs) into the mixer, there are generally no problems, but if I start addng more then the noise appears...

In fact a lot of the noise appears if I haven't even got them plugged into the mixer and just have the mains pluf of those keyboards plugged in (yet the powered off!!).

Arrrgh...

I'm convinced its the laptop, as when I run it from batteries its quiet....

Anyone have similar problems?
I read the stuff about the DI box but I don't think that would help for me as I output all my stuff into an old Hifi amp...

Your Spirit Folio is no doubt earthed via its mains plug, as are your keyboards, and probably your laptop, so you're an ideal candidate for ground loop problems I'm afraid. Have you followed the steps outlined in my 'tracking down problems' link in my previous post on this thread? that should help you determine what's causing the problem.

I do find ithard to believe that just pluggin in your other keyboards causes problems if they are not connected to your mixer via audio leads, but as soon as you do (apart from the balanced outs of your Promega 3) you could get problems. I made up pseudo-balanced leads between all my keyboards and synths and my analogue mixer.


Martin

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

Thanks Martin

can you explain what exactly pseudo balanced leads are.. I typed it into google and was lead to an old SOS article which provided a link that didn't work anymore.

Cheers

I explain all about them in this feature from SOS November 2004:

www.soundonsound.com/sos/nov04/articles/computerproblems.htm


Martin

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

I have an ASUS W3a with an Edirol fa66, which I bought because of the balanced in/out and I actually got around to buying some balanced cables yesterday. Plugged it all in expecting that my background noises would go away 'cause the outputs on the fa66 and inputs on my EMU 1820 are balanced but WAMO the horrible little digital gliteches are right there! They go away when on battery power and go away when I plug in my cheap car ground loop isolator, but I thought I would not have to do this with balanced to balanced connections! Will I will have to get a DI or a Behringer hum destroyer then?
Any ideas anyone?

Balanced cables should solve all ground loop problems assuming that the gear connected to both ends of the cable is balanced. Here's a reasonably definitive guide to interconnecting equipment from Rane:

www.rane.com/note110.html


Martin

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

Unfortunately Martin I seem to be one person that is still effected by horrible little electrical noises from my laptop when the laptop is operated from the power supply.
My emu 1820m has balanced ins and the fa-66 has balanced outs and I bought lynx balanced leads from Dolphin music http://www.dolphinmusic.co.uk/page/shop/flypage/product_id/3196.

Any suggestions at all on this one?

Oh and by the way, when I plug my EDIROL into the EMU via digital connection then there is no buzz or hum anymore!

Hmmmm....

Perhaps it's something to do with the chassis connections at both ends of those cables. As that Rane note link above shows, strictly speaking the screen of the cable should be connected at both ends, but sometimes this might result in noises remaining.

If you fancy the fiddle, try unscrewing the cable clamps at the output end of those cables and cutting the screen, or if you have a soldering iron unsolder it. The balanced connections only require the tip and ring parts, and the screen of the cable will still be earthed at one end, so this shouldn't affect its capabilities, but it might just kill those noises for you.

What you're effectively doing is converting your cables to number 8 wiring in the RaneNote.

The digital connection, being optical, also breaks the ground connection between the two items of gear.


Martin

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

Hi Martin

Thanks for your replies, just to make you feel better, i did read all those before posting!

I will continue to experiment to find the problem, but from reading all the posts I am very surprised the DI box didn't remedy it as that seems to fix 99%

The power cable is a round cable as you mention in your posts

Thanks, pete

--------------------
www.petewatson.com

Quote Martin Walker:

---

In addition to the above two links to FAQs on this forum, I also wrote a more general and extremely systematic 'tracking down ground loop problems' Q & A for SOS July 2005 that may help those with larger setups, and of course those without laptops:

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


Martin

---

Martin, I don't know whether it's just me but that article comes up all blacked out for me.

A few questions further to the above: Does one have to spec any particular kind of DI box for these duties? Or just get any bog standard cheapie one and insert it between audio output and mixer?

Also, I have problem with low level hum in my studio where I have a Flying Cow A/D converter connected to a Spirit Compact 4 mixer connected to Event TR8 monitors, ALL using balanced cables. The feed from the PC to the Flying Cow is digital, SPDIF. How can this be, if balanced cabling is supposed to solve such problems?

Hi Wurli!

Now that's strange - Firefox informed me a few days ago that version 1.5.0.2 was ready for download, and when I viewed that article it was black for me as well. I assumed it was some quirk of the update, but if it's happened to you as well I'll inform Ian to see if it's a forum quirk (by the way, for anyone else who finds it 'blacked out', just use the Ctrl-A 'select all' keyboard shortcut and you'll be able to read it again).

The quality of DI boxes is the subject of various threads on the Music Recording Technology forum - plenty of people have bought Behringer DI-20 boxes and been happy; others swaer by more expensive solutions, but there are plenty of recommendations in the threads I mentioned.

Re your low-level hum - only Toslink optical will break a ground loop. S/PDIF on the other hand uses standard phono connectors, so plugging in such a cable can occasionally cause problems.


Martin

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

Hi everyone,

i got rid of *all* the buzzing and humming noises that remained after disconnecting the groundloop from my Inspiron 8200 by installing generic AC97 chipset drivers. The clou about those were that they let me access all ins/outs that Dell disabled from the mixer panel without actually turning them off. Not sure if generic drivers are available for every chipset but it's worth trying to hunt for some.

Sincerly,
Ronny

Where did you get those drivers, Ronny? (and what OS are you running and bla bla bla) I have a Dell (latitude) so I'm in the same sad boat.

I got the drivers from a friend of mine, i can check if i still have the zip somewhere.

Anyway, you may try your luck googling for 'generic ac97 drivers' and see what comes around.

Ronny

--------------------
http://www.ronnypries.de - free loops, cherrypicked vst news & reviews etc...

I have this problem so am looking at ebay for a DI box.
Does it make a difference (apart from price & power supply) if it is active or passive?
Thanks
Nick

NOTTNICK:

Martin W says passive here:

http://www.soundonsound.com/forum/showflat.php?Cat=&Number=317&page=2&view =collapsed&sb=5&o=&fpart=1#317

There’s also a really good long thread about DI boxes and transformers here:

http://www.soundonsound.com/forum/showflat.php?Cat=&Number=266039&page=2&v iew=collapsed&sb=5&o=&fpart=1#266039

I think I’ll try me a cleanbox, reviewed by Paul White here:

http://www.soundonsound.com/sos/aug05/articles/studioessentials.htm

Ronny:

Sorry to be a pest, but do you have a little more information? What version of windoze are you running? What soundcard are you using? What do you mean about the in/outs disabled by Dell?

My notebook comes with preinstalled XP professional so I’m a bit reticent to start mucking about with generic drivers, but on the other hand your claims are pretty attractive and sound like they’re worth looking into. Did you find that zip? Does anyone else know anything about Dell vs. generic device drivers?

thanks again
ryan

Yes, passive is fine Nick - you don't want any more electronic circuitry in the way of your audio than is necessary.

And that ART Cleanbox II comes highly recommended Ryan (the original Cleanbox is a slightly different beast by the way).


Martin

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

Quote Martin Walker:

---

Re your low-level hum - only Toslink optical will break a ground loop. S/PDIF on the other hand uses standard phono connectors, so plugging in such a cable can occasionally cause problems.

---

OK, so if I have a hum in the following routing:

Soundcard S/PDIF Out > Phono Cable > D/A Converter > Balanced Jack Cable > Mixer > Balanced Jack Cable > Monitors

You're saying the culprit is likely to be the first link in the chain - the phono cable from soundcard to converter - even though it's carrying a digital rather than analogue signal?

If so, how would I use a DI box to overcome this? Presumeably I couldn't insert it between the soundcard and converter, where the problem is, because you can't DI a digital signal, can you?

So would I put it between the converter and mixer, like so:

Soundcard S/PDIF Out > Phono Cable > D/A Converter > Balanced Jack Cable > DI Box > Balanced Jack Cable > Mixer > Balanced Jack Cable > Monitors?

Thanks

This seems like a tricky one, and I'm not sure there's an easy way out of it Wurli - you can't really break the coaxial digital earth, and presumably the soundcard is earthed via the PC mains lead, and the converter box via its mains lead, so the loop is being caused by that digital cable.

Try to minimise the hum by making sure the PC and Converter mains leads are plugged in right next to each other, and try to use a coaxial digital cables that's as short as possible. Plug in the mixer and monitor mains cables as close as possible too to the PC and converter as well.


Martin

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

Here is a variation on the theme.

Laptop running on batteries with an Echo Indigo DJ PCMCIA soundcard with the latest drivers. Software is Ableton Live 5.2.

Laptop is Toshiba Satellite Pro SP40. 2.66 GHz Pentium with just short of 1 gig of RAM.

Sounds like I'm getting digital overs two or three times in each bar, even when I turn down the faders, and even though the 'VU' displays in Ableton are well clear of the 'red'. Checking the Echo console application shows no reds either.

I have checked for CPU, memory and disk access spikes - everything running within tolerance.

Here's the really weird bit: if I plug a USB device (memory stick, mp3 player or Wacom tablet) into one of the usb ports, the dodgy sound disappears.

It isn't spoiling my fun, because I (accidentally) found a work-around. But I'm buggered if I understand what is going on and why.

--------------------
Instant gratification is actually pretty good. It's fast as well.

That IS a weird one.

No idea of what causes it at all, unless there's some sort of intermittent connection that you cure by pushing in the USB plug.


Martin

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

Well, the ART Cleanbox II hasn’t done anything to solve my Dell Latitude woes. That is, the transformer seems to be faithfully reproducing the digital noise and passing it on to the rest of the system, so I guess the noise from the Dell is completely unrelated to ground loop issues.

Well I hope the ART Cleanbox II comes in handy for something else monkslut.

However, you should have been able to test whether or not your problem connecting the Dell Latitude to the rest of your system was ground-loop related by temporarily disconnecting it and plugging in some headphones to the laptop instead - if the noises disappeared when listening on headphones the problem could probably been cured with the Cleanbox; if not then you could have saved your money


Martin

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

Never mind

Here's the link to my step-by-step guide to tracking down ground loops again, which explains the process in more detail, but headphones are a handy tool for listening to audio at any point in your setup without it necessarily being connected to everything else. You just have to be systematic!

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


Martin

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

Thanks for the link and all the attention maintaining these (probably tiresome) threads Martin, but actually I’m not a ground loop problem guy. I’ve been a good boy; everything comes off one power circuit and nasty sources of pops like desk lamps come off other circuits even if it means power cords trailing seemingly irrationally around the room. And, ta-da, I have no ground hum or noise (when the fader for the notebook is down ).

I guess I was misled somewhere in all the posts thinking that the noise coming out of my cursed Dell Latitude notebook was groundloop related, and thus bought the Cleanbox.

I wish, instead of:

1) buying a Dell
2) reading your stickies

I had:

1) read your stickies
2) not bought a Dell

It is soon to be relegated to ancillary duty as the world’s most overcapable sequencer.

I am curious about Ronny's post above, claiming that by reinstalling some drivers he got rid of the noise, but no further information seems to be forthcoming.

cheers
ryan

ps cleanbox II for sale cheep