Have you been hearing some mysterious hums and/or buzzing sounds in the background of your productions? If you have, it could quite possibly be associated with ground loops of some sort.
I came across this problem as I was trying out a new headset microphone to use with both, “Audacity” and “mypodcast recorder”. You see, I use my laptop for almost everything I do at the moment because it is my fastest and best computer, as well as the most portable. (It is also my newest). I have been trying a lot of new things lately, for my own benefit and, hopefully, for yours. This led me to discover I had the above mentioned problem.
While doing some practice recordings with “mypodcast recorder”, I noticed a buzz in the background of my recordings. It was probably always there, I think the new microphone just helped me notice it more. For that I am thankful, because I really don’t like hums and buzzing and I find them quite distracting.
At first, I thought it had something to do with the mic, but substituting a different one proved that theory to be false. (The substitute generated the same thing, only a little softer in the background). It was beginning to really bother me. Now that I had heard it, my hearing really began to focus on it. I was determined to get rid of it, so the troubleshooting process continued.
I decided to see if it was associated somehow with the software, although it didn’t make sense it would be. I tried using “Audacity” and found the same thing once again. There was that distracting buzz in the background. I decided to go one step further with “Audacity” since I was planning to use it to directly record interviews over the telephone. I called a friend up and recorded the conversation, (with his permission of course). The result was horrible, (and I am being extremely nice about it). I was really begining to think I had a major problem and began to worry that some of my plans for the near and distant future were going to be out the window. I have to admit, it had me baffled, at least for the time being.
I began to look for possible ‘RF generators’ like lighting dimmers or something similar. Nothing I checked made any difference. I was really beginning to get concerned when the thought finally struck me. In audio work, we often contend with ground loops of one sort or another. We can usually temporarily lift a ground to test and isolate the problem. The problem was, I was not using any plugs with ground pins in them, just the standard two prong, so how was I going to lift the ground separately. I remembered I didn’t have the problem when I used only my portable digital recorder, to capture with. Nothing else was attached to it, so, what was the difference between the two ways?
(Well, I hope you haven’t guessed yet, because that would spoil the rest of this article.) It was the fact that the digital recorder was totally self-powered by battery and I was using the power supply/battery charger for my laptop. When I removed the power supply cord from the computer and it went on to its own battery power, the buzzing completely stopped. My recordings were once again clean in both, “Audacity” and “mypodcast recorder”.
The problem seems to have been a difference in ground potential (a ground loop) between the phone line and the electric in my house for the problem with the telephone buzzing. Removing the connection to the power line, removed the ground loop problem between it and the phone line. Now I just have to consider laptop battery life into the extended phone interview equation for the future. Hopefully, that is just a minor problem that I will be able to wring out soon.
I have to be honest. I still don’t fully understand why that cured the buzz in the microphone, but my theory has to do with the stereo plug it has. I think it has to do with the way the plug makes connection internally in the computer. To be technical about it, it is like inserting a balanced plug into an unbalanced input, or vice versa. At any rate I will keep working on that and let you know when I totally figure it out. If you have any ideas about it, please, feel free to leave your comments!
For now, though, all is much quieter on the recording end.
See ya next time . . .