USB Signal Noise

DJ Life & Community General Discussion
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1

USB Signal Noise

Hi Guys,

Having some trouble with my pair of Xone:K2s.
Ever since I got them, there’s been a low volume, high frequency noise emitted when connected via USB.
Here’s my setup.

Macbook Pro 13"
2 x Xone:K2
1 x Xone:smiley:B2.

1 Xone:K2 connected through a hub.
1 Xone:K2 connected directly to USB port.

Anyway, I haven’t really cared up until now as it’s hard to hear while playing, but it becomes evident during silent/low volume periods.

Note: The signal noise does change depending on how many LEDs are lit up on the device, but it is still there when there are none lit up.

I’ve tried different USB cables, ones with RFI chokes, different ports, direct connection etc.
As soon as the USB cable touches the socket, it starts to whine.

Is anyone else having this issue/know of anything I could do do eliminate it?

Cheers

2

Try using the K2s with the ethernet lines on the DB2.

3

Powered hub?

I would remove the earth\ground linkage from the power to your MacBook or Hub.. Sounds like a ground loop noise.

http://www.native-instruments.com/knowledge/questions/269/How+do+I+get+rid+of+humming+and+buzzing+sounds+(ground+loop)%3F

4

Would you? I’ve read about this (and it will definitely work), but it sounds dangerous…

5

Thanks, I’ll give this a shot. Though it’s probably not the ideal situation as I’d like to be able to plug my K2s in to any mixer and not have to rely on a XLink connection from a DB2/4.

6

I have no issues.

When I got my MacBook, it had the 2 pin plug, but I removed it and put on a 3 pin (like we use in South Africa) and did not connect the Yellow\Green wire…the ground.

Have not had an issue.

Its been 4 years?

:slight_smile:

7

I’ll quote from the above link:

“If you find the device that introduces the ground loop, a ground lift of the audio connection may solve the issue. Never lift the ground of the power connection!”

If you lift disconnect the mains earth cable you’re asking for trouble.

Ground lift ALWAYS refers to the audio signal NOT mains supply!

I suspect you have an issue with the power supply for the powered USB hub and probs need to replace it but to be honest why are you bothering?
You’ve got a DB2 why not use the X-Link?

You only need one USB back to your laptop from the DB2 and it then becomes your soundcard as well as your mixer.
Just daisy chain the K2’s off the X-Link socket using RJ45 cables

As an aside this will also improve your sound quality as you are only passing through one digital to analogue conversion as your DB2 outputs to the PA

8

The small plug adapter for Macbooks does not have a ground connection, whereas the longer cable extension does. Any laptop that uses a simple figure-of-8 adapter is ungrounded.

9

It’s actually recommended by NI that you use the longer cable extension if you’re having sound issues.

10

Switching to an ungrounded laptop power supply is a common fix for ground issues. I can’t think of any issue that would be solved by switching to a grounded cable.

11

Death by electric shock???

12

Does it happen when the Macbook is running on batteries - if so its possibly internal issue on the MacBooks USB port.

Does it happen when you are plugged directly into the Macbook without the hub ?

Does it happen on both K2 units ?

Do you still get a HF noise when you plug the K2 into the powered hub without connecting the laptop to the hub.

Grounding is normally LF not HF

13

Thanks for the replies.

First of all, the HF noise remains even while the macbook’s power cable is disconnected. - Does this remove the grounding problem theories?

The USB hub is not powered.

I’ll try connecting the K2s to the DB2 via XLink and use the DB2 as the soundcard. However this isn’t really the ideal situation as it would require a DB2/4 wherever I play. The reason I bought the K2s was for portability and this obviously defeats the purpose. But I’ll try it for troubleshooting’s sake.