noise when monitoring the A6 in a computer setup

Perfect Day · Joined: May 21, 2009 Posts: 53 Location: UK

Hi . Im currently experiencing some unwanted noise when monitoring my A6 from my external soundcard connected to my laptop . The noise soundslike an old computer loading up from tape . high pitched and screechy . If I move the mouse cursor I can hear sound why its moving . the funny thing is a have a prophet 08 as well and the sound isnt there if Im using this on its own . I can do a couple of things to make the sound disappear . 1 unplug my laptop from the mains and let it run on batterry power . 2 unplug the A6 cables from the soundcard . 3 unplug the A6 why the laptop is still plugged into the mains the noise only occurs when the A6 and laptop are plugged in together . Ive tried plugging them into different sockets it doesnt work one or the other has to be unplugged but theres no noise in the same set up between the computer and Prophet 08 (When the A6 isnt plugged in of course ? weird . I cant get my head round it does anybody know whats goin on . Thanks Im out of ideas ..Dave

Blue Hell · Posted: Tue Jun 02, 2009 1:08 pm Post subject:

Grounding trouble ... fairly standard, same thing here with different equipment ... ground lifting the laptop worked for me, i.e. plug it into an non-grounded outlet.

Perfect Day · Joined: May 21, 2009 Posts: 53 Location: UK

Hi . Is that not dangerous ? . Sorry I know nothing about grounding . How will I know if an outlets grounded or not . Thanks Dave

Blue Hell · Posted: Tue Jun 02, 2009 1:51 pm Post subject:

I'm not sure about how it works exactly in the UK, you are in the UK I think?

Perfect Day · Joined: May 21, 2009 Posts: 53 Location: UK

Yeh mate Im in the UK . Have you ever used a noise filtering power conditioner ?

Blue Hell · Posted: Tue Jun 02, 2009 2:22 pm Post subject:

No I didn't, and I doubt it work on this as it does not break the ground loop; and that is where the problem is.

Perfect Day · Joined: May 21, 2009 Posts: 53 Location: UK

Ok Thanks for the help . If it was a ground loop though would I not get the same problem when using the prophet 08 instead of the A6 . Thanks Dave

modulator_esp · Posted: Tue Jun 02, 2009 2:49 pm Post subject:

If you don't want to lift the earth you can actually buy something like this to break the ground loop

Posted Image, might have been reduced in size. Click Image to view fullscreen.

Posted Image, might have been reduced in size. Click Image to view fullscreen.

http://www.xitel.com/USA/prod_gli.htm

the P'08 won't have the same problem as it has an external PSU which doesn't have an earth IIRC

Muied Lumens · Posted: Tue Jun 02, 2009 2:56 pm Post subject:

Is your sound card a USB one? If so, try to take it out of the loop, just by plugging into the internal laptop line in. USB can often cause problems which are hard to cure in a simple way.

From your explanation, this does not sound like a ground loop, which is manifests itself as hum, but I would not rule it out completely. It does, however, sound more like radio frequency noise, which could be a result of bad or cheap cables. Try with different cables, as short as possible, and balanced if possible. Check with the manuals if the involved equipment is balanced.

I would not recommend breaking the ground to your power. This is potentially dangerous, as you rightly assume. The grounding is there as a safety in case a fault develops which could be fatal.

Perfect Day · Joined: May 21, 2009 Posts: 53 Location: UK

Hi just got some new planet waves cables today (unbalanced) I do have some balanced cables these are a cheaper cable but the problem is apparent with both . But the power supply for the laptop could be crap . Ive heard someone say that this is quite a common problem with laptops . Ive just unplugged the instrument cables from the A6 but left it switched on and plugged in and plugged the instrument cables into my Prophet and there is no noise now although the laptop is plugged in and audio cables are connected from the P8 to my soundcard . THe soundcard is USB by the way . Its an Edirol m16dx

Perfect Day · Joined: May 21, 2009 Posts: 53 Location: UK

Thanks for the help everyone . Speak soon

sunny pedaal · Posted: Wed Jun 03, 2009 12:15 am Post subject:

problem is the laptop, as the battery makes it dissapear , it's indeed a grounding problem . other powersupply might safe the problem , as well as other brand or newer laptop. try them out before buying.
noisfiltering etc isn't the appropriate way to solve this

Perfect Day · Joined: May 21, 2009 Posts: 53 Location: UK

It also disappears if I unplug the A6 while the laptop is still plugged in . Are u sure its grounding trouble ? Ive had an earth loop before which was buzzy or like a hum . This sounds like a commador 16 loading up . I can hear the computer processing

sunny pedaal · Posted: Wed Jun 03, 2009 12:52 am Post subject:

it might do all kind of strange things. but regarding the fact the when batterypowered the problem is gone , and when plugged in then it appears, it's almost certain a problem of the laptop/powersupply and not of the a6.
you might try to put on ( a6 or ltpowersupply) in a grounded powersocketdivider and the other in a ungrounded (only 2 cables connected, not the green one) . sometimes this solves the problem . however if you don't feel save 'bout it don't touch it and best: use the batterysupply instead when recording the a6 via the laptop.( or try another powersupply/laptop)

succes

modulator_esp · Posted: Wed Jun 03, 2009 2:24 am Post subject:

Your problem sounds like noise from the laptop is leaking into your audio signal path

I get a similar problem with my Nord G2 when I connect it to my laptop via USB which is stopped by disconnecting the mains power or by using the xitel ground loop isolator on the G2s audio outs

Perfect Day · Joined: May 21, 2009 Posts: 53 Location: UK

Thanks . Im gonna buy a behringer DI120 box today this changes unbalanced signals to balanced and lifts the ground on the signal . Ill let you know how I get on later .

modulator_esp · Posted: Wed Jun 03, 2009 6:07 am Post subject:

Perfect Day · Joined: May 21, 2009 Posts: 53 Location: UK

Just a thought before I do go out and buy a di box . My a6 has mutiple outs main ,aux (both stereo) and 8 other mono outputs . This Di box may solve the problem Im having with noise from the main output of the A6 into the inputs of my soundcard . But what will happen if I run out the aux simultaniously into the soundcard . Will I need another di box to stop hum on that input as well ?

modulator_esp · Posted: Wed Jun 03, 2009 10:12 am Post subject:

Perfect Day · Joined: May 21, 2009 Posts: 53 Location: UK

Thanks is there not a device to break the ground on the laptops power supply which is safe ? or maybe something to break the ground on the usb connection between my audio interface and computer . Thatd solve it wouldnt it ?

Shreddie · Joined: May 12, 2009 Posts: 96 Location: UK

Have a read of This thread.

pinealapoptosis · Posted: Thu Jun 04, 2009 1:15 am Post subject:

I had this same problem.Mine was a buzzing sound.I heard it anytime I had my pc's audio out hooked into an amp.It also happened when I had my interface hooked up via usb.This also only happened when my laptop was running off of ac power.Not battery.

After reading other peoples experiences,I deduced that I had a ground loop going.So I got one of those adapters that converts a three prong grounded male plug into a two prong male plug with no round ground prong.

problem solved.

sunny pedaal · Posted: Thu Jun 04, 2009 2:11 am Post subject:

i would go for the last tip, the a6 is then earthed . overall either earth everything or if it doesn't work , at least earth the part where most soundamplification takes part ( mixer or amp) . also connecting in a so called tree like way , whereby more to the point of the arrow the more important the earthing is might avoid earthing problems.
first rule however is that make sure all equipment is properly manufactored and not causing earthing problems on it's own, espec laptops/ "cheaper" powersupplies nowadays seem to have these problems.
lot of articles are found on this topic on almost all audio/studio fora, so seems to be a common problem