Hi, I sometimes record out live shows with my Sony minidisc, but the last to recordings was not so good. I use a Røde nt-3 mic condenser mic and record through the line in jack of the minidisc. The problem is that the recording starts loosing level and become very low in volume a few minutes into the recording. There's also a crackling noise a the volume peaks, like something is distorting. I've checked the batteries in the mic and minidísc, and I record with the rec level set manually. Any ideas?