The absolute beauty of tape based echo units lies in the fact that tape itself is analogue – moving the tape across a tape head polarizes the magnetic domains in the tape in proportion to the fluctuations in the audio signal. The granular nature of the magnetic material adds noise to the signal and because the magnetic characteristics of tape are not linear tape exhibits a characteristic hysteresis curve, which causes unwanted distortion of the signal. Any measured analog signal must theoretically have noise and a finite slew rate. It`s the imperfection in tape that makes the sound so delicious.