I have the same 50 Hz hum problem using a Logitech USB headset. The problem occurs using either Quicktime to make an audio recording or Screenflow.
I have tried unplugging the USB, replugging, sleeping the computer. However, I need assurance to know that when I record there will not be a humm.
It's certainly a mystery!
This is the advice provided on the Logitech website for a USB headset.... Sounds like the instructions typical of a Windows device!
Something not sound right? No sound at all?
- Is the headset cable inserted fully into the computer’s USB port?
- Try increasing the volume in both the application and operating system.
- Try restarting the media application.
- Close all media applications and make the B530 the default audio device:
Windows XP: Go to Start/Control Panel/ Sounds and Audio Devices/Audio tab.
In the Sound Playback/Default Device window, choose the Logitech B530 USB Headset.
Click OK. Restart the media application. Windows Vista and Windows 7: Go to Start/ Control Panel/Sounds/Playback Devices tab. Choose Playback Devices and the Logitech B530 USB Headset. Click Set Default, and then click OK. Restart the media application.
Mac OS X: Open System Preferences. Select Sound/Output tab, and then select the Logitech B530 USB Headset.
Restart media application.
- Using a non-powered USB hub may degrade headset performance. Try plugging the headset directly into a USB port on