Well I tried increasing microphone gain and volume and computer volume and playing back through the computer. It was still hard to locate any change of hum inside the closet when I moved the mic around, and nothing changed when I touched the mic. I did notice a slight change when I got down close to where my desktop sat on the other side of the wall, though, so I decided to drill a hole in the wall so that cord length would allow me to put the desktop about 4 feet away, and that seems to have solved it! When I plot the spectrum of noise, I rarely have any 120 hz peaks, and when I do they never seem to be higher than -70dB or so.
I also decided to re-record, being more careful about maintaining mic position between recordings. Here’s the (raw) transition between a recording I finished last night and one I started this morning. The difference seems much less pronounced to me.
Any other thoughts on the sound quality of this sample? Does it sound like decently clean raw audio?
That is a very workable test recording. I had to apply a small amount of compression to get it to meet the ACX rms-peak requirements, and used the “LF Rolloff for Speech” equalization curve to get rid of the 1/f noise – that improves the S/N ratio by about 3 dB.
Getting the microphone to work is only first of three parts. Then you have to pass Theatrical Quality which is judged by Human Quality Control at ACX followed by actual theater. We have to enjoy what you’re doing.