Rather than use the head to generate tiny currents, which must then be filtered, amplified, and decoded, an MR head uses the head as a resistor. A circuit passes a voltage through the head and watches for the voltage to change, which occurs when the resistance of the head changes as it passes through the flux reversals on the media. This mechanism for using the head results in a much stronger and clearer signal of what was on the media and enables the density to be increased.