problem with recording...groundloop?

amatsov · Post by **amatsov** » Mon Sep 14, 2009 9:58 am

hi,

I ve got a problem with recording and I would ask for some help.
if I play my synths and drummachines everything sounds nice and clean, until I open my laptop with cubase and try to record.
a hum or hiss comes in and it makes a good qualty recording impossible.
sometimes its very strong sometimes not so much.
I play my old analogs straight into my Edirol FA-101.
is there someting I am missing from my equipment of is this the groundloop?
what can I do about it?

thanks in advance!

Allan

taskoni · Post by **taskoni** » Mon Sep 14, 2009 10:44 am

Hey.
Just a thought - try disconnecting the power cable of the laptop and try again. Some laptops (PC's mainly) like Sony Vaio for example bring hum because their power cables are not grounded... If the hum is still there you might start checking cables etc.
Hope that helps a little.
Regards,
Boris

amatsov · Post by **amatsov** » Mon Sep 14, 2009 10:58 am

thanks Boris!
yeah, I tried that...does not help even, if the PC is working on battarey.

pflosi · Post by **pflosi** » Mon Sep 14, 2009 11:39 am

make sure none of the audio cables crosses wallwarts, and if they have to, make sure they do at 90°

amatsov · Post by **amatsov** » Wed Sep 16, 2009 9:10 am

I reconnected all my cables and none of them cross the wallwarts.
hum is still there...

pflosi · Post by **pflosi** » Wed Sep 16, 2009 9:18 am

hmmm... i think it might be something with your audio interface then...

i see the edirol thing can be used bus powered. are you using it that way? if so, try using the PSU for the interface... might help as well (if the PSU has a proper ground, and if that's the problem...)

by the way, what's your OS? Mac? I had very bad hum once when trying to connect a FW audio interface to a windows laptop, which had only a mini-FW input, so i took a big-to-mini plug, that produced very bad hum

Post by **Stab Frenzy** » Wed Sep 16, 2009 9:36 am

It's not a mac, he's got grounding issues.

OP: You've got problems with the ground on your laptop, basically it's not earthed and it everything else is, so it's earthing through the earths of more than one of your synths. Are you connecting your interface with a 4 pin cable? (The small firewire plug, not the big one) That's often a cause of grounding problems.

IIRC the FA-101 doesn't have a standalone mixer mode, so you can't check the signal without the laptop connected. Just in case it's one of the synths or drum machines try disconnecting them all with your monitors attached to the interface still and then if there's no hum reconnect them one by one to see if you can isolate the cause, but my money's on the problem being the laptop itself, a lot of IBM compatible PCs are designed cheaply and aren't really suited for audio use.

pflosi · Post by **pflosi** » Wed Sep 16, 2009 10:46 am

Stab Frenzy wrote:It's not a mac, he's got grounding issues.

But - if the laptop is the problem - shouldnt the hum go away when disconnecting the PSU of that laptop, i.e. only working on batteries...?

Post by **Stab Frenzy** » Thu Sep 17, 2009 1:42 am

No, if I'm right the problem is that the laptop's not grounded. If everything's grounded properly you don't have ground loop issues, it's when something's not grounded and it tries to ground through another device that the problems occur.

amatsov · Post by **amatsov** » Thu Sep 17, 2009 11:56 am

yeah Stab could be right...I `ll go home and give it a try.
I am useing PC with PSU and I am connecting Edirol with a 4 pin cable.
the hum is not there when I am listening to my mp3 from a computer through FA-101 but it comes "alive" when I try to record synths.
when laptop is closed and i am playing synths its clean.
what are rhe options to ground my PC?

problem with recording...groundloop?

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