Garrett ACE series
Garrett ACE 400 Target ID Chart and What Iron Audio Adds
Quick answer
The Garrett ACE 400 reads on a 0 to 99 digital target ID scale with the same conductivity ordering as the rest of the ACE line: iron low, foil and small gold below the middle, nickels and tabs mid scale, copper and silver high. Iron Audio is what separates it, letting you hear discriminated iron rather than only see a number.
Garrett states that the ACE 400 carries a 0 to 99 numeric digital target ID, Iron Audio so you can hear iron trash before digging it, electronic pinpointing through a non-motion all-metal mode, and an adjustable frequency for interference. Those are the published features, and the Iron Audio line is the one that changes how you work.
The bands below describe the ordering on the machine's ruler. They are not Garrett's numbers, because Garrett does not publish a target-by-target lookup, and anybody who prints one as though it were official is guessing on your behalf. If you are choosing between models, the ACE 300 chart uses the same structure so you can compare like for like.
Top pick
Garrett ACE 400
Iron Audio is the reason to pay the difference over the 300: it turns a suspicious high number into an audible ferrous grunt before you cut a plug.
Price was accurate when this page was compiled and changes often.
What does the ACE 400 add over the 300 on target ID?
Two things, and only one of them is on the screen. The first is Iron Audio, which Garrett describes as letting you hear iron trash before digging, including bottle caps and washers. The second is that Garrett's published specifications put the 400 at a higher operating frequency than the 300, which makes it more responsive to small, low conductive targets such as thin gold and small hammered silver, at some cost in stability on heavily mineralised ground.
Neither changes the ordering of the scale. A nickel still sits mid scale, silver still sits at the top. What changes is how much confidence you can put in a marginal reading, because you get a second, audible opinion about whether iron is involved.
What does each band read on an ACE 400?
Same ruler, same ordering, same caveats. The bands widen at the bottom because low conductors are where machines disagree most.
On the ACE 400 the mid scale from roughly 50 to 75 is where nickels, pull tabs and most gold jewellery overlap, and no amount of discrimination separates them cleanly on a single-frequency machine.
| Target | Typical band (0 to 99) | Iron Audio behaviour | Confidence |
|---|---|---|---|
| Nails, wire, small iron | 0 to 35 | Grunts clearly | High; leave it |
| Bottle cap, rusted steel | Bounces 30 to 80 | Grunts underneath the high reading | This is the case Iron Audio exists for |
| Foil, thin chain | 20 to 45 | Silent | Low; overlaps small gold |
| Small or thin gold ring | 30 to 60 | Silent | Low; indistinguishable from tabs by number alone |
| US nickel | 50 to 60 | Silent | High; one of the steadiest readings on the scale |
| Pull tab, can slaw | 55 to 75 | Silent | Moderate; dig the band or accept you will miss rings |
| Zinc cent | 68 to 80 | Silent | Moderate; corrodes and drifts down in acid soil |
| Copper cent, dime | 78 to 86 | Silent | High when shallow |
| Quarter, large copper | 82 to 90 | Silent | High when shallow, wanders when deep |
| Silver half or dollar | 88 to 95 and up | Silent | High; the cleanest signal most people ever hear |
Bands describe the conductivity ordering on the machine's own 0 to 99 ruler and are not manufacturer-published values. Soil chemistry, moisture, depth, target orientation, corrosion and firmware all shift them. Verify in your own ground before you trust any of it.
How should you actually use Iron Audio?
Turn it on and leave it on for the first season. The purpose is not to reject more, it is to let you hear what the discrimination circuit is quietly throwing away. A target that gives a clean high number with an iron grunt underneath it is usually a bottle cap or a non-ferrous object sitting against a nail, and the tone tells you which before you cut turf.
On an old house site with heavy iron, the usual working method is Iron Audio on, discrimination minimal, sweep speed halved, and a small coil if you own one. That combination digs more rubbish per hour and finds the objects everyone else walked over. The coil compatibility chart is worth reading before you buy anything, because the ACE and AT lines are not interchangeable in the way people assume.
What pairs with an ACE 400?
Audio is the channel this machine gives you extra information on, so the headphones matter more here than on a simpler detector.
Garrett ACE 400
$357.99Iron Audio, a 0 to 99 target ID and adjustable frequency at $357.99.
Best for: iron-heavy park and field ground
Check price on Amazon
Garrett MS-2 Headphones
$33.99A plain wired pair with a quarter inch right angle plug and a volume control, and no battery to go flat mid session.
Best for: a spare pair that lives in the bag
Check price on Amazon
Garrett Pro-Pointer II
$99.99The non-submersible Pro-Pointer, cheaper than the AT version and fine if you never detect in water.
Best for: dry-land hunting on a tighter budget
Check price on AmazonHow we chose
We did not test these machines in person and we publish no find claims. Picks are researched from manufacturer specifications and owner manuals, published listing features, waterproof ratings and warranty terms, and the recurring themes in verified owner reviews. We favour the established detector brands because coils, shafts and control boxes have to stay available years after a model is discontinued, and we place every pick in the tier where its price and capability honestly belong.
Sources
- Garrett ACE 400 owner's manual
- Garrett ACE 400 published feature listing, including Iron Audio and the 0 to 99 digital target ID
- Garrett ACE series specification sheet, for operating frequency by model
Frequently asked questions
Is the ACE 400 target ID scale the same as the ACE 300?
Both machines carry a numeric 0 to 99 digital target ID, and the conductivity ordering is the same on each: iron low, mid conductors in the middle, copper and silver high. The readings are not guaranteed to be identical target for target, because Garrett publishes a higher operating frequency for the 400. If you upgrade, rebury your test targets and rebuild your card.
What is Iron Audio on a Garrett ACE 400?
Garrett describes it as a feature that lets you hear iron trash before digging, naming bottle caps and washers specifically. In practice it makes discriminated ferrous targets audible instead of silent, so a high target ID with an iron grunt under it reveals itself as a cap rather than a coin. It does not change the number on the screen, only what you hear alongside it.
Will an ACE 400 find gold rings?
It will detect them, and so will the 200 and the 300. The difficulty is identification, not detection: small and thin gold reads low on the scale and overlaps foil and pull tabs almost exactly. Anyone who consistently finds rings does it by digging the mid range and accepting a high trash ratio, not by finding a magic setting that separates gold from aluminium.
Does a bigger coil change the target ID numbers?
It changes them at depth. A larger coil reaches deeper but averages a wider patch of ground, so targets close together blur into one reading and marginal deep targets report lower and less stably. A smaller coil gives cleaner numbers in trash at the cost of coverage. Check compatibility before buying, because ACE coils and AT coils are not the same fitment.
Is the ACE 400 waterproof?
The searchcoil is; the control box is not. Garrett's ACE listings state the PROformance searchcoil can be submerged in shallow water, streams or damp shoreline sand while the control box is not waterproof. The AT line is the Garrett family that is listed as fully submersible, to ten feet. Treat an ACE as rain-tolerant rather than water-capable.
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.