The ACE 400 is a mid-level VLF (Very Low Frequency) metal detector from Garrett’s ACE series. It improves on some of the simpler ACE models by adding more user control, a better coil, more features aimed at separating trash from treasure, and somewhat better sensitivity, especially for non-ferrous metals like gold and jewelry. It’s not a specialist gold machine (PI or multi-frequency), but it offers a good compromise for coin hunting, relic hunting, and general treasure work.
Practical Field Performance — What It Does Well
Based on user tests and reviews, here are where the ACE 400 tends to perform well:
Coin, Jewelry, and Relic Hunting in Moderate Soils
In parks, fields, old homesteads, and similar ground with moderate soil mineralisation, the ACE 400 does quite well. Depth for coin-sized targets is generally good (in many cases up to ~8–10 inches depending on soil).
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Trash Management
Thanks to Iron Discrimination, Notch Discrimination, Iron Audio, and digital target ID, users can avoid a lot of junk (nails, bottle caps) or at least know what they are listening to. This saves digging time and helps focus on more promising signals.
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Ease of Use / Learning Curve
Because it has preset modes plus a “Custom” mode, many users find it easy to start detecting right away, but also to gradually tweak settings as they learn. The adjustable shaft and lighter weight help for longer detecting sessions.
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Coverage Area
The 8.5×11″ DD coil gives good ground coverage per sweep. That helps cover more area faster. Also, DD coils tend to handle ground mineralization better than concentric coils in many situations.
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Limitations & Where It Struggles
To be realistic, the ACE 400 has several limits. Depending on what kind of searching / gold prospecting / terrain you plan, these might be important.
No Manual Ground Balance
The detector has a fixed (factory) ground balance, which you cannot change. In soils with heavy mineralization (iron oxides, hot rocks, etc.), or in wet salt-sand, this limitation causes more false signals, unstable operation, and reduced depth.
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Not Fully Submersible
Even though the coil is waterproof, the control unit is not. This means while it works in shallow water or wet conditions, it is not suitable for underwater work, or hunting in surf zones or depths where the control housing would be submerged.
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Gold Nugget / Small Gold Detection is Limited
Because 10 kHz is moderate but not ultra high, and because of the fixed ground balance, detecting very small gold flakes or micro-nuggets (especially in highly mineralised ground) will be challenging. Larger gold jewelry or rings are detectible under good conditions, but fine prospecting for tiny gold is not its strong suit.
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Metal Pursuits
Salt / Wet Sand Difficulties
Wet sand or saltwater tends to cause interference and false signals, especially since ground balance is not adjustable. Users often report more noise/false targets in beach/wet conditions if close to the water.
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Display & Screen Features Limited
Some users mention there is no backlight (or the backlight is minimal), and target ID + discrimination graph is useful but not as rich or adjustable as in some higher-end models. Tone customization, depth readout precision, etc., are not as advanced.
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Best Practice / Tuning Advice
If you have an ACE 400 (or are considering one), here are field tips to get more out of it:
Start in a mode close to your environment — e.g. Coins or Jewelry mode if you’re doing coin/ring hunting, Custom if you want to tweak away trash.
Set sensitivity carefully — increase until you get chatter or false signals, then back it off one or two levels. That helps stability.
Use Iron Audio in trashy areas — helps you hear what the detector is rejecting; sometimes “bad” iron IDs hide good non-ferrous metal close by.
When in wet sand or near water, reduce sensitivity, increase discrimination, and sweep slowly to avoid noise. Avoid submerging control unit.
Practice with test targets — such as coins, nails, gold rings, small jewelry — to get a feel for what each Target ID number sounds like or what tone it gives in your soil. This helps you interpret signals better.
Keep coil clean and wire tight — coil wire slack or damage causes interference or erratic signals.
Watch battery level — using 4 AA batteries, changes in battery power can affect sensitivity or stability. Replace or use good rechargeable AAs.
Is the ACE 400 Good for Gold Treasure Hunting?
Short answer: yes, but with caveats.
It will detect gold items like rings or larger pieces if the soil conditions are decent (lower mineralization, smaller amounts of interference).
It is not optimized for finding very small flakes or deeply buried nuggets, especially in mineralized ground. It lacks some of the specialized features (manual ground balancing, high frequency + multi-frequency or PI) that high-end gold detectors have.
If your treasure hunting focus is gold jewelry, coins, relics — especially in parks, fields, or dry terrain — the ACE 400 can do a good job.
If you plan to hunt in very rough terrain, wet salty sand, or want tiny natural gold, you may want to consider stepping up to detectors specialized for gold, or multi-frequency/PI models.
Conclusion
The Garrett ACE 400 is a strong detector in its class: it offers a lot of usable features, especially for beginners to intermediate users who want more than just a basic machine but don’t want to invest in top-tier gold prospecting gear.
It hits a good balance of:
solid sensitivity for general treasure (coins, jewelry, relics),
good coil design,
useful discrimination and audio tools (Iron Audio etc.),
decent portability and usability.
Its limitations are mostly in more challenging environments: wet salt conditions, highly mineralized ground, deep/very small gold targets. If those are your hunting conditions, you’ll need either to accept some compromise (lower depth, more digging, more false signals), or budget for a higher-spec detector.
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