RF: A Ghost In My Machine?

by | Studio Equipment

Has anything like this happened to you?

Today, I experienced some wierd noises coming through my mixer , headphones and into my ProTools session. 

These sounds even registered as little blips in the wav file. It sounded like someone was talking (very muted) , and I couldn’t understand it–but it caused me to re-record a number of times in order to get a clean audio file.

I remember at one of the radio stations I worked at, (WQFM-FM, Milwaukee), we had carrier current broadcasting a MUZAK  channel  simultaneously from our rock station’s antenna on the station’s roof.  I recall our station engineer telling me, “It’s RF” , those ubiquitous and unpredictable radio frequencies we could hear through our headphones, and in the station’s signal. That was back in the 1970’s. Fast forward to the present, now with ever-present additional wired and wireless devices we all own, sound waves are all around us. No wonder.
I turned my mixer on & off- I was running  ProTools, my MS Outlook and IE7. Could this noise have been some RF rolling off of some cell phone, Ipod, wireless internet, baby monitor or bluetooth nearby into my orbit …while I am trying to record  a project for (don’t laugh, now) LG ?

Had my mixer or or mic cable become an unknowing antenna? I decided to do some research and fell upon  this helpful decsription of RF at wisegeek.  Another technical, but clear description was found in “What is Radio Frequency?”

Here’s my concern. Everything is already grounded, shielded and plugged into power strips and my APC battery backup. And it’s not a hum…it sounds like someone is talking.

If there are any suggestions, I’d like to know about them, and will share them here.


  1. Hey Bobbin!
    How frustrating!
    I don’t have an answer, but a question: Was it raining/or had it just rained by any chance?
    When I was working at a small market radio station we would get RF in the production studio whenever it rained! Sometimes it was so bad we had to postpone production till the air/ground/whatever dried out!…NO one could ever figure it out…we just learned to live with it…luckily we weren’t in Seattle!

    Home one of the techies can help!



  2. Hey Liz….DON”T YOU KNOW…. It doesn’t rain in Southern California, girlfriend (lol) ….at east hardly ever at this time of the year. Hope somebody will be able to help me.
    I love the fact that you stopped by and left me a comment. You’re the best!

  3. Bobbin, I’ve had this problem a couple of times. A local station has a tower about half a mile from here. It certainly was a shock the first time it happened! The cable from my sound card to my preamp was actually an unbalanced one, and since replacing it with a balanced cable I have not had a problem (but then, it had only happened a few times and the future stretches ahead – here’s hoping). Maybe you can connect with other recording artists in your area and see if anyone else has had the same experience. Good luck!


  4. i’ll be watching this with interest, bobbin. a few years ago, i was constantly bedeviled by “snowman”…an old coot with nothing to say who said it proud and loud over his over-juiced cb or ham radio somewhere in the neighborhood. one of the many strands of cable in my studio picked him up regularly and i never figured out how to block it.

    one day “snowman” just went away. i figure either the fcc was finally alerted to the guy…or he melted.

    may you have similar relief, sooner.

  5. Rowell & Mary,
    I appreciate your remarks. Since my problem has only occured intermittently, my hope is that it will be fleeting. But I’ll keep digging around for a solution. I am going to pursue the  suggestion Mary offers on the “balanced cable” angle, and talk with some audio folks up at the VOICE conference about this as well.
    All the Best,

  6. Did you try turning down the mic input on the mixer to isolate the problem? If anything is acting like an antenna, it would more than likely be the xlr.
    Try swapping it out with a new one. The solder might have come off at the connector and it is no longer grounded.
    They also make numerous xlr ground lifts, ISO Transformers and Direct Boxes to elimate the problem.
    Good luck!

  7. Hi Bobbin, I have had a similar issue with my Pro Tools sessions in the past. How much RAM do you have in your machine and what is your processor speed?

    When I upgraded from 1.5 gigs of RAM to 3 gigs, I never had the issue again. As you may know, Pro Tools is known as a RAM HOG and you need to have the maximum amount in there. Why this didn’t show up in the past is beyond me, but once I added RAM, it immediately went away.

  8. Bobbin, what makes a cable balanced or unbalanced is wicked complicated to me since I somehow got 3 degrees in biology without ever taking physics (interestingly, the one area of physics that interested me and that I pursued on my own was the physics of sound. Prescience!!). But I can tell you this much. An XLR cable is likely to be balanced, and cables with two phone plugs (like the 1/8” or ¼” stereo or mono plugs we’re used to seeing in this biz) are likely (likely, I say! no guarantees) to be unbalanced. So, if you have a cable with phone plugs running from your preamp to your sound card or audio interface, and you have the option of switching to an XLR cable, you should consider doing that. The cable I’m using has an XLR plug at one end and a phone plug at the other, and I made sure to ask if it was balanced when I bought it. And I haven’t had problems with RF since.

    Do I sound like I know what I’m talking about? Didn’t think so!! I’d be interested to hear what kind of cable you’re using – that is, what it looks like on the outside.


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