High-pitched squeal and low buzz at regular intervals using NTG-2 and DR-40

[Darren Byers]

Hi,

I'm a total newbie, and I'm guessing this question has been asked before...

Last year we filmed our first feature length movie. I was using a Rode NTG-2 and the Tascam DR-40.

I noticed that there is a high-pitched squeal and a low rumble at regular intervals on some recordings. Sometimes I just hear the high-pitched squeal, other times the buzz and sometimes both.

See here for an example: https://www.dropbox.com/s/yop8hl9i8lz7xj7/TASCAM_issue.wav?dl=0

Does anyone know what is causing it?

Thanks,
Darren.