Essentially, your MXT, like all Transmit/Receive models, operates on a volume-change or loudness change principle. Generally, as you sweep over a target the volume or loudness increases until your coil is directly centered over the target. Most makes and models will have the same audio tone (pitch or frequency) and simply get louder. The closer the target is to the coil, the more volume, and the farther from the coil the weaker the volume.
Your T/R unit does feature two audio enhancing Pinpoint mode characteristics. One is associated with the Gain (sensitivity) control when you increase it to the +1, +2 and +3 ranges. When you do, the circuitry goes through 'steps' that both increase the TARGET VOLUME as well as the audio saturation. This is similar to the Modulation On/Off feature of the XLT or DFX. At the preset ot lower settings, the audio response is more modulated. That is, louder on shallower targets and diminished audio (weaker) responses as the coil-to-target distance increases.
But when set at +3, for example, not only are eyou increasing the Target Volume, but you are more or less turning Modulation OFF (or Saturation On, if you will) such that the same loud audio response of a shallow target will be provided on those in a mid-range or slightly deeper distance from the coil.
The other audio enhancing function your MXT providess, without the option to turn it On or Off, is VCO audio. What Voltage Controlled Oscillation does, basically, is increase the audio pitch or frequency as well as the volume. So you hear not just a loudness change but a pitch change. It is excellent for help in pinponting target. I have found the VCO audio in White's circuitry to be some of the absolute best in the industry.
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