The angle between the gap in a tape head and the longitudinal axis of the tape (should be 90 degrees).
"I received my 3 CDs that you made from my cassettes. The sound quality was much better than I had expected. My songs had a lot of strings in them and a clear / high note sound was very important to me. Your CD copies kept the strings nice and clear with sharp tones just as I had wanted. Thanks, good job!! I also noticed where some LP pops and ..."