Garrett AT series
Garrett Iron Audio Settings Chart: What It Does and When to Use It
Quick answer
Iron Audio makes discriminated iron audible again as a low grunt instead of silencing it, so you can hear a flattened bottle cap or a masked coin before you dig. Garrett fits it to the Garrett AT Pro, Garrett AT Max, Garrett AT Gold and Garrett ACE 400. It changes nothing about depth.
Iron Audio is one of the few detector features that does exactly what its name says and is still widely misunderstood. It does not reject iron, improve depth, or make a machine more sensitive. It changes what the detector tells you about the iron it has already decided to discriminate away.
Normally, a discriminated target is silent. Silence is ambiguous: it could mean nothing is there, or it could mean a nail is there, or it could mean a nail is there with a dime beside it. Iron Audio removes that ambiguity by letting the iron speak in a low grunt, which is the single most useful thing it does.
Top pick
Garrett AT Pro
Iron Audio combined with Pro mode proportional audio and 40 levels of iron discrimination, which is what makes the bottle cap check work.
Price was accurate when this page was compiled and changes often.
On this page
Which Garrett machines have Iron Audio and what does each do?
Garrett uses several related features under different names, and they are not the same thing. The distinctions below come from each machine's published feature descriptions.
Garrett fits true Iron Audio to the AT Pro, AT Max, AT Gold and ACE 400, while the ACE 300 offers iron resolution only and the newer Apex and Vortex VX9 replace the on and off switch with an adjustable iron volume control.
| Machine | Feature | What it does | Control |
|---|---|---|---|
| Garrett AT Pro | Iron Audio, 40 level iron discrimination | Makes discriminated iron audible and resolves the iron range finely | On and off, plus discrimination level |
| Garrett AT Max | Iron Audio | Audibly identifies discriminated iron so it can be avoided | On and off |
| Garrett AT Gold | Iron Audio | Audibly identifies iron targets in a machine often run wide open | On and off |
| Garrett ACE 400 | Iron Audio | Hear iron trash such as bottle caps and washers before digging | On and off |
| Garrett ACE 300 | Iron resolution | Improved discrimination between good targets and iron. Not the same as Iron Audio | Discrimination only |
| Garrett ACE Apex | Iron volume control | Adjusts the volume of iron targets independently of good signals | Variable level |
| Garrett Vortex VX9 | Iron volume and high resolution iron discrimination | Variable iron volume plus fine iron discrimination | Variable level |
Feature descriptions taken from Garrett listing specifications for each machine. The ACE 300 offers iron resolution rather than Iron Audio, which is a distinction worth knowing before buying one for bottle cap country.
What should Iron Audio be set to by site type?
Iron Audio is a switch on the AT line rather than a level, so the decision is when to use it rather than how much. On the Apex and Vortex it is a volume, which allows a middle position that the AT machines do not have.
Leave Iron Audio on all day on relic sites and in bottle cap country, use it as a spot check in parks and old yards, and switch it off in clean field soil and on beaches where constant iron grunting only causes fatigue.
| Site | Iron Audio | Why |
|---|---|---|
| Relic site, heavy iron | On, all day | The iron is the map. You need to hear what you are walking over |
| Old house site or foundation | On | Nails everywhere, and good targets hiding between them |
| Mown park, bottle caps | Spot check | Switch on when a high tone looks doubtful, off the rest of the time |
| School yard or sports field | Spot check | Modern trash, mostly aluminium, less iron to reveal |
| Open field, low trash | Off | Nothing to reveal and the grunting costs you concentration |
| Dry beach | Off | Very little ferrous trash. Fatigue is the only outcome |
| Wet salt sand | Off | The machine is already struggling with the salt signal |
| Goldfield, All Metal | Not applicable | Nothing is discriminated in All Metal, so there is nothing to make audible |
Practical guidance based on how the feature works, not a Garrett recommendation. The right answer depends on how much ferrous trash your ground holds and how long you can listen to it without tuning out.
How do you use Iron Audio to check a bottle cap?
A steel crown cap is ferrous, but its flat disc shape produces an eddy current response close enough to a coin that the machine can report a high conductive number. With Iron Audio on, the same sweep produces the high tone plus a low iron grunt, and that combination is the tell. A genuine coin gives the high tone alone.
Sweep from a second direction at ninety degrees before deciding, because a coin lying beside a nail can produce the same mixed response and that one is worth digging. This is the check that saves the most digging in modern parks, and it works alongside the audio behaviour described on the AT Pro tone profiles page.
What does Iron Audio not do?
It does not add depth, it does not reduce iron falsing, and it does not improve target ID accuracy. It also does not help at all in a true All Metal mode, because nothing is being discriminated, so there is no silenced iron to reveal. That catches out AT Gold owners who switch it on while prospecting and wonder why nothing changed, which is why the AT Gold settings table marks it as not applicable in that mode.
The real cost is fatigue. On genuinely iron-infested ground, Iron Audio turns a quiet hunt into a continuous low grumble, and after a couple of hours people stop processing the information they switched it on to receive. Decent headphones help, which is where the Garrett MS-2 Headphones or the wireless Garrett MS-3 Z-Lynk Wireless Headphones earn their place, but no headphone fixes concentration.
How do you train yourself on the iron grunt?
Lay a nail, a flattened bottle cap, a coin, and a coin beside a nail on the ground, all on the surface where you can see them. Sweep each with Iron Audio off, then on, and listen to the difference deliberately. Then bury the same set at three or four inches and repeat, because a buried mixed target sounds nothing like a surface one.
Half an hour of that is worth more than any written description, including this page, because you are calibrating your ear to your machine and your soil. Do it again whenever you change coils or headphones, since both change the character of every tone you have learned.
Sources
- Garrett AT Pro, AT Max and AT Gold owner's manuals, Iron Audio sections
- Garrett ACE 300 and ACE 400 listing specifications, iron resolution and Iron Audio
- Garrett ACE Apex and Vortex VX9 listing specifications, iron volume control
Frequently asked questions
What does Iron Audio actually do on a Garrett detector?
It makes discriminated iron audible again as a low grunt instead of leaving it silent. Nothing about detection changes. What changes is that silence stops being ambiguous, so you can tell an empty patch of ground from a nail, and a coin from a flattened bottle cap that is reporting a high conductive number. It is an information feature, not a performance feature.
Should I leave Iron Audio on all the time?
On relic sites and old house sites, yes, because the iron is part of what you need to know. In parks it is better used as a check on doubtful high tones, since constant grunting is tiring and people stop listening properly after a couple of hours. On clean ground and beaches it adds nothing at all, because there is little ferrous trash to reveal.
Does Iron Audio work in All Metal mode?
No, and this catches people out. All Metal discriminates nothing, so there is no silenced iron for the feature to make audible. On an AT Gold used for prospecting in True All Metal you are already hearing every ferrous target, which is the point of the mode. Iron Audio only has a job when a discrimination pattern is doing the silencing.
Is iron volume on the Apex the same as Iron Audio?
It is the same idea with finer control. Garrett describes the Apex iron volume control as adjusting the volume of iron targets independently while keeping desirable signals clear, so instead of an on and off switch you choose how loudly iron speaks. That allows a quiet background level of iron information without the full volume grumble the AT machines produce.
Can Iron Audio help me find coins masked by nails?
It can warn you that both are present, which is genuinely useful, but it cannot separate them. A mixed response that changes with sweep direction is the signature to look for. The actual separation problem is a coil problem, and fitting a smaller coil such as the 5 by 8 DD will resolve targets that no audio setting can untangle.
Researched, not professional advice. This page is compiled from published specifications, manuals and owner-review consensus, not hands-on testing. Target ID numbers, depth figures and settings vary with soil chemistry, moisture, target size, depth, orientation and firmware version, so treat every figure here as a starting point and verify it against your own machine's manual and your own ground. As an Amazon Associate we earn from qualifying purchases.