Click here to purchase the entire book in PDF format. DC Bias We started in Section 6.3.3 by wishing that analog tape had a perfectly linear transfer function, but we found out that it doesn't. However, we did see in Figure 6.62 that there are linear components on the tape's M-H curve. These can be used to our advantage as is shown in Figure 6.63. Figure 6.63: Let's take our audio signal and ensure that its peak-peak amplitude is about the same as the size of one of the two linear components on the tape's M-H curve. We then apply a DC offset (usually called a DC bias) to the signal so that it sits on one of the linear portions of the curve. This will actually work - we'll get a linear representation of our signal stored on the analog tape and we'll be able to read it back with a playback head. The only problem is that we're not using the full potential of the tape, so we get a very poor signal to noise ratio.