DC hum on USB

[benstechshow]

I'm having an odd problem here I have a DC hum comming from all of the USB both on my motherboard and the PCI USB card.
The biggist thing that puzzles me is When I record my show I use the usb (iMic II) to send my audio/my voice to my co host using skype and then record my cohost and my self using the sound card that is built into the motherboard and I get the hum with in the recording But I dont hear the DC hum thru the mixer!
Kinda odd I know I hope some one can help
Thanks
Ben Straw
www.benstechshow.com
Mac Tip Podcast - Tips And Hints for your Mac

[brandondrury]

This hum stuff is always tricky because it could be an electrical grounding issue, something in the computer (software or hardware) or any number of issues.

What audio interface are you using? Is there any change the signal is being blended with another signal within the computer after your mixer? Does the problem occur when you aren't using Skype?

Brandon

[benstechshow]

The computer is a dell inspiron 530, the sound card I have no clue what is is, the usb device is a Griffin iMic2, Mixer a Yamaha MG102c, the computer and the mixer are on the same circuit, there is no hum when I'm not using skype, The mixer doesnt have the hum nor the sound from the sound card

[garww]

I don't understand why you would think you have DC hum ?
I have Skype on my laptop but have no clue what it is. If it is a communications device, it's probably generating "interference".

[benstechshow]

Skype is a program to call other people. I use to for my show to bring in guests and cohosts that are all over the world. Now the way I have to set it up so that I can record both the guests and my voice but still have them hear me and not them selves is what called a mixer minus ok... Now in order for me do do this I need a usb sound card IE. the iMic II so my guests hear me
the problem is I can record any sound i want but if I use the imic to record with I get a hum.
I've tryed different cables and 2 other iMics with the same problem

[garww]

Elimination tells you what the problems is. If you insist on using the noisy device you will probably have to shield your external components and hope that helps.

[brandondrury]

there is no hum when I'm not using skype

Well, it sounds like you've got it figured out. Now it's time to dig deeper. Is the hum caused the second you turn skype on or is it caused when you connect with your buddy?

Brandon

[garww]

There is a reference that v3.0 keeps enabling the soundcard mic port ??