"I use the Delta 1010 audio interface with my Cool Edit Pro computer audio program. From time to time, it doesn't seem that the level I'm actually recording and the meters in the software are representing the same values. Sometimes the meters show a high level, but the audio I get back is much, much quieter than at other times. How is this possible and what can I do about it?"

This may be a DC offset issue. Many sound cards such as the Delta 1010 can sometimes record audio with a slight DC offset, which means that the center or zero amplitude point of the waveform being recorded would not be at the exact vertical center of the waveform display, but a little above or below it. This effectively "biases" the signal in a more positive or negative direction than it really should be. This can (sometimes dramatically) throw the level meters off since the amount the waveform is displaced could be interpreted as a constant sound that loud. This added DC component to your audio also eats up a corresponding amount of headroom in your system - the DC energy IS recorded, you just don't hear it.

While this can cause a variety of related problems, there is an easy fix. Enable ''Adjust for DC'' in Cool Edit. In the current version of Cool Edit, select Device Properties from the Options menu. Then select the Wave In tab that allows you to select any sound card installed on the PC, and check the Adjust to 0 DC check box. You can also adjust DC on an existing file. With the file open, select the Edit view and go into Effects Amplify/Amplitude and check the box for DC. Most quality audio software programs have some means to remove any DC from audio. It's generally a good idea to do so if you suspect you have a problem.