Garrett AT Pro Tone Profiles: What Each Tone Is Telling You

The AT Pro's tone assignment follows the conductivity scale, so the pitch ordering matches the number ordering described on the target ID chart.

In Standard mode the AT Pro gives you a flat, binary response: the target is either there or it is not. In Pro mode the response becomes proportional, so a whisper means a weak signal and a strong tone means a strong one. That is the difference between knowing a target exists and knowing roughly how deep and how large it is before you cut the turf.

Tone roll adds the second dimension. As the coil passes over an object, the pitch rolls rather than stepping, which exposes the character of the signal. A round coin gives a smooth, symmetrical roll. A bent piece of aluminium gives a ragged one. Iron beside a good target gives a roll that changes shape when you approach from a different angle. None of that appears on the screen, which is why people who learn the audio outperform people who watch the number.

Iron Audio makes discriminated iron audible again as a low grunt, instead of silencing it. The target has not changed. What changed is whether the machine tells you about it. On a flattened bottle cap you get the high tone plus the iron grunt, and that combination is the tell. The full treatment is on the Iron Audio settings chart, including which site types justify leaving it on all day.

The cost is fatigue. In genuinely iron-infested ground, Iron Audio turns a quiet hunt into constant noise, and after two hours people start tuning out the very information they switched it on for. Use it as a check on suspicious signals rather than as a permanent state, unless you are hunting relics where the iron itself is the map.

Substantially. The AT Pro's deepest targets arrive as faint, short responses, and a speaker outdoors in wind loses them entirely. Garrett ships the Garrett MS-2 Headphones with the AT Pro, which is a plain wired pair with volume control and is entirely adequate. The Garrett MS-3 Z-Lynk Wireless Headphones adds Z-Lynk wireless, which suits people who keep catching the cable on brush. The Garrett Submersible Headphones is the wired set required if the machine goes under water, because wireless audio does not pass through it.

Whichever set you use, learn it and keep it. Switching headphones changes the perceived character of every tone you have trained on, and half a season of ear calibration goes with them.

A high tone that repeats from two directions with a stable number is worth digging in almost any context. A high tone that only speaks from one direction is worth investigating, because it is either deep, on the edge of the coil, or masked. A medium tone is a judgement call that depends entirely on whether you are hunting jewellery. A low grunt with no high component is worth digging only on a relic site.

The one signal people misjudge most often is the broken high tone. It is usually aluminium, occasionally a coin next to iron, and the only way to resolve it is a smaller coil or a different angle. If your site is full of them, the coil compatibility chart is a more productive read than any settings guide, and the dig time budget will tell you whether chasing them fits in the hours you have.