Laptop Firewire = noisy audio out

fultro wrote on 7/25/2008, 7:20 PM
Setting up a laptop with a Focusrite Saffire firewire box.
--I get noise that sounds like a low gurgling with a high whine on top.
--This happens with the onboard firewire connector.
--This also happens with the Cardbus Firewire adapter.
--This happens even when the Focusrite is not powered up.
--Happens with 6 pin or 4 pin
--Some cables are less noisy than others.
--Moving the cable back and forth in the jack I can find a low noise 'sweet spot" . This in any of the outputs with any cable.

--Given all of this it does not seem like a bad jack or cable issue.
--If the Focusrite is not even turned on it seems as tho it can't be that.
--Could it be a driver issue ?

Any thoughts would be greatly appreciated - - -

Comments

farss wrote on 7/25/2008, 7:43 PM
I'm confused, where is this noise coming out of?
Do you mean from the speakers in the laptop itself?

If so it's probably from the laptops own audio section and it's noise from the power supply and/or induction from other things happening in the laptop. The external cables could have an impact on this as well. Just guessing here but that's my best shot without more info.

Bob.
fultro wrote on 7/25/2008, 9:03 PM
signal path : laptop firewire out (onboard jack or Cardbus jack) > Focusrite Saffire breakout box > external sprs.
Noise does not occur in laptop headphone jack nor does it sound like induced 60 cycle hum
Moving the cable in the jack changes the noise level as if there were a bad jack or cable except for the fact that the problem occurs with any of the jacks and with any cables
farss wrote on 7/25/2008, 11:19 PM
What kind of external speakers?

I have a pair of Behringers that have much the same problem as the inputs even though XLRs aren't exactly "balanced" and they pickup the local TV xmitter and induced noise from the PC / Forewire 410.

A set of line isolation transformers might cure the problem or some small value capctors to filter RF. You could try better grounding onto the speakers or different power point.

Bob.
fultro wrote on 7/28/2008, 9:34 PM
it seems that it is a problem with my Yamaha HS-50M pwrd mons.

--a different audio device with a USB out produces the same prob with those spkrs.

-and using cheap PC desktop spkrs with the Focusrite does not produce the prob.

-very strange - lifted the ground on the Yamaha's too
John_Cline wrote on 7/28/2008, 9:37 PM
Does this happen when the laptop is powered off the battery?
fultro wrote on 7/29/2008, 11:30 AM
nope - no battery installed