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.
An analog recording is one where the original sound signal is modulated onto another physical medium or substrate such as the groove of a gramophone disc or the iron oxide surface of a magnetic tape. A physical quality in the medium (e.g., the intensity of the magnetic field or the path of a record groove) is directly related, or analogous, to the physical properties of the original sound (e.g., the amplitude, phase, etc.)
how to get a fat tone from his Les Paul. Well, tone is a particularly personal matter but also comes in as many flavours as the imagination. Alot of TONE variation is achievable simply through your guitar to start with.