What Is Causing This Noise?

[soundchaser59]

the person with the cell phone will be gone all day today. Be interessting to see if the noise returns when she does!

[Manslick]

Yep it's a cell phone. When my brother is in my truck I can tell when he's about to get a call because that exact same sound comes thru the radio.

[ralpheo]

That's funny, because I have the 1616 pci into a pcmcia adapter. I have my phone on in my studio all the time and I never get that interference. Check your xlr cable. Try the amp again with the Heil in front of it when you know shes on the phone. I don't think it's going to be exclusive to the Shure. Good Luck.

[soundchaser59]

The person with the cell phone left and the noise continued. I siwtched the mic cables left and right, but the noise continued to be in the left input. I put the phones into the mic preamp and there was no noise at all. So I knew the noise was not coming from the mic or the mic pre. It had to start at the Emu dock.

You guys talking about wireless stuff got me to looking more closely at what is going on in my studio. Since my Sonar machine is in the basement but I need to authorize software, etc., I use the wireless connection to my router upstairs.

The 1616 dock has two mic inputs on it. A couple days ago I changed my wireless configuration and I set the computer's little 3 inch tall wireless antenna on top of the Emu dock, directly above the left mic input. Didn't give it a second thought. Then I remembered that the wireless connection will periodically (probably about every 60 seconds) "talk to the router" to make sure it is still there and the key code is still valid.

So, by watching this little systray icon.....


I noticed that the noise in the left input only happened when the green "network communication" light comes on in the systray icon. I waited for it to happen again, and as soon as I moved the little antenna away from the dock, the noise disappeared.

Whoda thunk it? Your hints about wireless EMI set me up to figger this one out! So THANKS people!!

[ralpheo]

Oops! Forgot to say anything...
Glad we could be of help -- even if we were wrong!

[soundchaser59]

Naaawww..... you guys weren't wrong, you had the wireless idea right, just fingered the wrong wireless device. Same principle, though..... it put me on the right track!

[dgatwood]

The funny thing is that I almost said, "Or Wi-Fi", but thought about it and concluded that the emissions from a Wi-Fi device could never cause that in practice because they don't slam the carrier on and off rapidly like GSM devices do. They're spread spectrum, not time domain.

Of course I wasn't even considering that you might put a transmitting antenna an inch from your audio hardware with a wireless driver that aggressively manages transmit power.... Yeah, I could see that being a problem.