Short answer: buy the ACE 400 if you hunt trashy ground, buy the ACE 300 if you hunt clean ground and want to keep the difference in your pocket. The two machines share the same display, the same 0 to 99 Target ID, the same five search modes and the same body, so the decision comes down to three real differences: Iron Audio, the coil that ships in the box, and the operating frequency.
Everything else you will read about these two is noise. We stock both, we have run both, and the honest version is that most first-time buyers overthink this decision and a smaller group of experienced hunters underthink it. Here is the breakdown that actually changes what you dig.
Garrett ACE 300 vs 400: Spec Comparison
| Specification | Garrett ACE 300 | Garrett ACE 400 |
|---|---|---|
| Position in the ACE line | Mid tier | Top of the traditional ACE line |
| Operating frequency | 8 kHz, adjustable | 10 kHz, adjustable |
| Coil included | 7" x 10" concentric PROformance | 8.5" x 11" DD PROformance, waterproof |
| Iron Audio | No | Yes |
| Digital Target ID | 0 to 99 | 0 to 99 |
| Iron discrimination segments | 4 | 4 |
| Notch discrimination | Adjustable | Adjustable |
| Search modes | 5 plus Pinpoint | 5 plus Pinpoint |
| Sensitivity / depth adjustments | 8 | 8 |
| Audio tone ID levels | 3 | 3 |
| Target depth indicator | Yes | Yes |
| Weight | 2.8 lb (1.27 kg) | 2.9 lb (1.32 kg) |
| Shaft length | 40" to 53" | 40" to 53" |
| Batteries | 4 AA, included | 4 AA, included |
| Warranty | 3 year limited parts and labor | 3 year limited parts and labor |
Read that table again and notice how much is identical. Same target ID resolution, same four iron segments, same eight sensitivity steps, same three tones, same shaft, same batteries, same warranty. Garrett did not build two different detectors here. They built one detector and gave the higher model a better coil, a faster frequency, and one feature that the lower model does not have at any price.
The Four Differences That Matter in the Field
1. Iron Audio, and why it is the whole argument
This is the difference that changes your dig ratio, and it is the one buyers skip past because the name sounds like a minor audio setting.
When you discriminate iron out on an ACE 300, the iron goes silent. That sounds like what you want until you meet a flattened bottle cap. A crushed steel cap sits in the ground behaving like a mid-conductor and reads up in the zinc penny range, somewhere around 60 to 70 on the Target ID. The 300 gives you a clean high tone and a believable number, and you dig a cap. Then you dig another one.
Iron Audio on the ACE 400 lets the discriminated iron leak back into the audio as a low growl underneath the good tone. You still get the high signal, but now you also hear the iron signature riding along with it. A real coin sounds clean. A bottle cap sounds clean with a grunt in it. After a couple of hunts your ear does the sorting automatically and you stop cutting plugs for trash.
In a clean, tested field with almost no iron, this feature does very little. In a city park, an old school ground, a fairground, or any farm field that has been lived on, it is worth the whole step up by itself.
2. Coil and depth: the coil does more work than the frequency
The spec sheet difference people fixate on is 8 kHz versus 10 kHz. The difference that actually shows up in the hole is the coil.
The ACE 300 ships with a 7" x 10" concentric coil. A concentric coil projects a cone-shaped detection field, which makes pinpointing intuitive and gives a nice symmetrical signal. It is a genuinely good coil in mild soil, and it is easier for a new detectorist to learn on because the target is exactly where the signal peaks.
The ACE 400 ships with the 8.5" x 11" DD coil, which is waterproof and submersible. A DD coil projects a blade-shaped field running front to back. That shape does three useful things: it covers more ground per sweep, it handles mineralized soil far better because less ground is under the coil at any moment, and it separates targets that sit close together instead of blending them into one signal.
On raw depth over a clad quarter in mild dirt, the two are close. Call it an inch, maybe less, and some of that inch comes from the larger coil rather than the frequency. Where the 400 genuinely pulls away is in mineralized ground, in iron-heavy sites, and on small low-conductive targets like thin gold, lead, and small silver, where the higher 10 kHz frequency lifts the response that 8 kHz leaves quiet.
If you hunt clean turf and cut lawns, that gap narrows to almost nothing. If you hunt red clay, black sand, or an old home site laced with nails, it is not close.
3. Target ID stability
Both machines put the same 0 to 99 scale on the screen. They do not deliver it with the same steadiness.
Target ID is only as good as the number of clean looks the coil gets at the target. The 400's DD field is narrow side to side, so a target stays inside the sensitive zone longer through the sweep and gets sampled more consistently. Numbers settle down and hold. The 300's concentric field is wider and shallower in shape, so on deep targets and on targets sitting next to iron, the ID has more room to bounce.
Practically: on both machines, a shallow coin locks solid and you can trust the number. On a 7 inch coin next to a nail, the 400 will give you a repeatable reading you can act on and the 300 will give you a range you have to interpret. Neither is wrong. One just asks less of you.
4. Weight and balance
The spec is 2.8 lb versus 2.9 lb. That is 1.6 ounces, and anyone who tells you they feel it in the first hour is telling you a story.
What you can feel over a long hunt is balance, not mass. The 400's larger coil sits further out on the shaft and puts slightly more of the machine ahead of your wrist. Some people notice it at hour four, most never do, and an armrest adjustment fixes it for almost everyone. Do not let 1.6 ounces decide this purchase.
The Upgrade Path Is a Trap, and Here Is the Coil Math
The obvious move for a budget buyer looks like this: buy the ACE 300, bank the savings, and add the bigger DD coil later if the ground turns out to need it.
Run that plan all the way out before you commit to it. The ACE Series 8.5" x 11" PROformance DD coil is one of the more expensive accessories in the ACE range, and an ACE 300 bought new plus that coil lands above the cost of simply buying an ACE 400 outright. You would spend more to get there, and you still would not have Iron Audio, because Iron Audio is built into the 400's circuitry and no coil or accessory will add it to a 300.
Check current pricing on both ACE 300 and ACE 400 listings before you buy, because the gap moves with promotions. The relationship holds either way: the DD coil costs enough on its own that the upgrade path is more expensive than the upgrade.
If budget really is the binding constraint, the smarter play is an open box ACE 300 rather than a stripped new one. Open box widens the gap between the two machines and makes the 300 a much more interesting proposition for anyone hunting clean ground.
Which One Should You Buy?
Buy the Garrett ACE 300 if...
- You hunt mown parks, sports fields, beaches, and other relatively clean ground
- You are buying your first serious machine and want to learn on a coil that pinpoints simply
- Coins and jewelry are the goal, not relics in nail-infested soil
- The money saved is better spent on a pinpointer, a digger, and a finds pouch, which is a defensible call for a first setup
- You want the strongest machine you can get without moving up a price tier
Buy the Garrett ACE 400 if...
- Your sites have iron in them: old home sites, farm fields, fairgrounds, curb strips, anywhere people lived before 1950
- You are tired of digging bottle caps, or you have not started yet and would like to skip that phase entirely
- Your soil is mineralized and your current machine goes unstable when you turn sensitivity up
- You hunt small gold and thin silver, where 10 kHz earns its keep
- You expect to still be detecting in three years, in which case the step up amortizes into nothing
If you are still deciding between the ACE Series and everything else on the market, our guide to the best metal detectors for beginners puts both machines in context against the rest of the entry and mid tier, and the Garrett buying guide covers where the ACE line sits against the AT series.
FAQ
What is the main difference between the Garrett ACE 300 and ACE 400?
Iron Audio. The ACE 400 has it and the ACE 300 does not, and it cannot be added later. The 400 also ships with a larger 8.5" x 11" DD coil instead of a 7" x 10" concentric, and runs at 10 kHz instead of 8 kHz.
Is the Garrett ACE 400 worth the extra money over the ACE 300?
In iron-heavy or mineralized ground, yes, comfortably. In clean turf where you are mostly chasing modern coins and jewelry, the ACE 300 does nearly the same job for meaningfully less.
Does the Garrett ACE 300 have Iron Audio?
No. Iron Audio is exclusive to the ACE 400 in the traditional ACE lineup. No coil, accessory, or setting change will add it to an ACE 300.
Is the ACE 400 deeper than the ACE 300?
Slightly, and most of the gain comes from the larger DD coil rather than the frequency. On a clad coin in mild soil expect about an inch. In mineralized soil or on small low-conductive targets, the margin is wider.
Can you put the ACE 400 coil on an ACE 300?
Yes, the ACE Series shares a coil connector, and the 8.5" x 11" DD coil fits the 300. Bought separately it costs enough that an ACE 300 plus that coil ends up dearer than an ACE 400, and it still leaves you without Iron Audio.
Is the Garrett ACE 300 good for beginners?
It is one of the better first machines you can buy. Five preset modes, one-touch operation, a readable 0 to 99 Target ID, and a concentric coil that pinpoints predictably make the learning curve short.
Are the ACE 300 and ACE 400 waterproof?
The control housings are not. The ACE 400's 8.5" x 11" DD coil is waterproof and submersible, so both machines handle rain and shallow wading at the coil, but neither should be dunked at the control box.
The Bottom Line
These are the same detector wearing different coils, and Iron Audio is the one feature that draws a hard line between them. Clean ground and a tight budget point to the Garrett ACE 300. Iron in the soil, or any real ambition toward relics, points to the Garrett ACE 400, and the coil math means there is no cheaper way to get there later.
If both sit above your budget, look at our more affordable machines before you compromise on a toy. If you want to see how the ACE line stacks against the rest of the range, browse the full Garrett lineup or our complete selection of metal detectors.
