We discuss decrease in the decay rate of the TEM voltage response in cases when TEM soundings are performed using central loop arrays with small-size transmitter loops. We show that the cause of the slowly decaying central loop TEM voltage response is the intrinsic transient response of the measuring amplifier. This effect is the more noticeable the smaller the transmitter loop and/or the more resistive the ground. The effect is not observed when the receiver loop is located outside the transmitter loop. Inversion of the late time TEM response without regards to the intrinsic response of measuring unit results in appearance of nonexistent conductive ground layers and thus in misinterpretation of the TEM data. To reduce the intrinsic transient response of the measuring amplifier, the following may be useful: reduction of the latest measurement time, subtracting the intrinsic transient response from the total one, disconnection of the amplifier from the receiver loop during the current turnoff in the transmitter loop.