darbyshiretheman

Hi, I have a avtech 4ch dvr, i have audio connected on 2 of the channels, when playing back every few seconds it cuts out and makes like a popping sound,sounds like some tapping the mic, i have tried different mics so i don't think it is that, there is no settings in the box that i can see.When listening to live audio it is dine it is just on playback but it is really bad.I have tried normal mic's and pre-amplified mics as well as adjusting the gain etc. Please can anyone help? Thanks