The Samson CO1U USB Condenser Mic is an inexpensive USB microphone you can use for podcasting and screencasting. As I understand it, unless the software you're using on the Mac allows you to control audio input, you're going to have a Mono signal in one channel. Some software will allow you to configure the mic for mono input. GarageBand will, for example, so you can get audio in both channels. But I'm using Vara Software's Screenflow, which doesn't yet allow that kind of control of the audio settings in the current version.

To get around this, you need to change your input settings.

1. Open Applications > Utilities > Audio Midi Setup.app
2. Select your connected Samson C01U mic in the "Properties For:" drop down menu. The "Audio Input" area should refresh to show format options.
3. In the Format field, change the channel drop down menu to "1ch-16 bit."

Your audio application show now send mono for both channels.