The signal-to-noise ratio of a magnetic tape reproduce system is discussed. An expression for the theoretical value of the signal-to-average-band-limited-noise is developed in terms of the statistical properties of the signal and the probable noise sources. The concept of power spectral density is used to simplify the discussion and to develop insight into system behavior. The resultant system equations are then recast in terms of the physical properties of the system to demonstrate the effects of materials construction geometry, and electronics noise on the SNR. The theoretical discussion is correlated with experimental data for verification.