Garrett ACE 400 Metal Detector Review

Affordable, powerful, perfect for beginners
Written By: Marc McDermott
Last Updated:

Looking for a quality-built, professional metal detector that doesn’t break the bank? Look no farther than the Garrett ACE 400. 

What we like:

  • Iron Audio
  • Large, DD coil
  • Digital Target ID
  • Easy to use
  • Affordable, yet powerful

What we don’t like:

  • No ground balance adjustment
  • Can be too heavy for young kids
  • Included headphones are cheap

The ACE 400 is the upgraded version of the now discontinued ACE 350.

It has new features such as iron audio, digital target ID, adjustable frequency, and cam locks for additional stability (see today’s price).

So if you thought the ACE 350 was a good machine (and it was), then you’ll be quite happy with the ACE 400.


Let’s jump into some of the features of this detector. I’ll start with the new features not found on the ACE 350 since those will be more interesting to explore.

Digital Target ID

One of the few things Garrett users complained about in the old ACE series was the lack of digital target ID – the 0-99 numeric ID on the LCD screen.

The ACE 350 did not have this feature, rather it used a segment identification process.

Essentially it would tell you if it thought the target was a particular type of metal such as iron, gold, copper, silver, etc.

The only real issue with the segment approach is that it’s too broad in its metal identification.

The 0-99 scale is the same basic principle but provides a much more accurate representation of your target.

So instead of the ACE 350 telling you that you have a quarter in the ground, the ACE 400 can actually tell you if that quarter is silver or clad and if a penny is copper or clad – pretty neat.

Here is where common coin targets will hit on the 0-99 scale (note that these numbers will change in the field based on ground conditions, depth, nearby targets, etc.).

  • U.S Clad Quarter: 87-90
  • U.S Clad Dime: 83-85
  • U.S Clad Nickel: 42-45
  • U.S Clad Penny: 77-80

Iron audio

Iron Audio is an impressive feature to have in such an inexpensive detector.

This feature creates a low, grunting tone if any iron is detected in the target. Note that you must be using some level of iron discrimination for this to work. This feature does not work in the ‘Zero-Disc’ mode since iron is not being discriminated in that mode.

Why should you be excited as I am about iron audio? If you’ve ever been metal detecting before with an entry-level machine, you know that it’s very easy to be fooled by trash targets.

Things like bottle caps and washers will look and sound just like a coin signal. And you end up wasting valuable time digging up trash.

Iron Audio allows you to double-check a target before you dig it. So when you think you have a good target, flip on iron audio and listen for that low, grunt.

This is a terrific feature to have and is not usually found in entry-level detectors.

Adjustable frequency

While the ACE 400 is a single frequency VLF machine broadcasting at 10 kHz, it does give you the ability to adjust the frequency ever so slightly if you need.

This is great if you’re hunting with a friend who also has the ACE 400 – or even a different brand detector operating at the same frequency. The detectors will end up detecting each other if you get too close.

This happens a lot if you tend to hunt in groups or participate in competition hunts where the likelihood is high that someone there is using the same machine.

Power lines and other electrical interference such as WIFI signals can also make a metal detector go nuts.

Adjusting the frequency is not something you need to do on your average hunt, but is an invaluable feature to have on those occasions when it’s needed.

Cam locks​

The last feature I’ll talk about that’s new to the ACE 400 is the addition of cam locks.

Camlocks are a simple, plastic locking mechanism that adds strength and stability to your detector.

Camlocks give the detector shaft extra stability and prevent the three pieces from wobbling as your swing.

The ACE 400 breaks down into three pieces, as does almost every metal detector.

Because of this, the areas where the pieces meet are weak and can sort of make the detector wobble when you swing it.

Camlocks tighten up those joints and make the detector feel like one solid piece.

Search modes

Like the ACE 350, the ACE 400 comes with five search modes:

  • Zero discrimination
  • Coins
  • Jewelry
  • Relics
  • Custom

These are factory discrimination modes/patterns and are ideal for beginners.

You can adapt any of these modes by using the notch feature with the custom mode.

An example of why you would want to do this is if you wanted to hunt for coins, but you only wanted silver coins.

You could start in the coin mode, then notch out the segments for nickel, copper, and zinc.

So if you’re in an old park where there’s likely to be silver coins, you might not want to spend your entire day digging new memorial pennies.

Other features​

Here are some additional features and specifications:

  • Three tones (low, medium, high) based on the size and conductivity of the target.
  • Pinpoint mode to zero in on targets.
  • Sensitivity adjustment for maximum depth and to avoid falsing.
  • Depth indicator so you have a general idea how deep to dig.
  • Large, 8.5×11” DD coil for greater depth and better iron discrimination.

Detector comparisons

I talked about how the ACE 400 stacks up against the ACE 350, now let’s talk about how it compares to a few other popular machines.

ACE 400 vs. AT Pro

The AT Pro is the next step up from the ACE 400 in the Garrett lineup.

It’s an all-terrain, fully submersible machine that’s perfect for all types of detectorists.

Some of its features not found in the ACE 400 include:

  • Proportional audio mode
  • Additional iron discrimination controls
  • Faster recovery speed
  • Higher frequency (15 kHz) for more sensitivity to smaller objects
  • Automatic ground balance (major difference)

For the average user who doesn’t need a waterproof detector, the biggest advantage by far is the automatic ground balance in the AT Pro.

The ACE 400 uses a factory preset ground balance which cannot be adjusted in the field.

You can read our complete review of the AT Pro here.

ACE 400 vs. ACE 300

We covered the next step up in the Garrett lineup, now let’s talk about the next step down – the ACE 300.

A true entry-level machine, the ACE 300 is also a great option if you have a tighter budget and can’t afford the ACE 400. Or if you just want to get your feet wet in this hobby and don’t want to spend a load of cash upfront.

The ACE 300 looks a lot like the ACE 400, but has two fundamental differences:

  1. Smaller 7×10 concentric coil which gets you less depth and less iron discrimination.
  2. No iron audio making it harder to differentiate between good targets and trash.

Both ACE detectors are similar in size and shape.

Both detectors have a very similar control box.

The ACE 400 uses a much larger, DD coil.

The control boxes are about the same in terms of size and weight.

See my review of the ACE 300 here.

ACE 400 vs. ACE 400i

Ok, so I see this question come up quite a bit on the forums. The difference between the 400 and 400i.

The “i” stands for international – meaning the international version.

There’s really no difference apart from some additional iron discrimination features to handle the highly mineralized soil conditions found in Europe.

The 400i also does not have U.S coins as target ID segments.

The 400i is not available in the United States.


Here are answers to some of the more commonly asked questions:​

ACE 400 Depth

Like any metal detector, depth depends on several factors including machine settings, ground conditions, target size, etc. Generally speaking, you should be able to reach a U.S quarter at 8-10” in neutral ground.

What size coil comes stock with the ACE 400?​

The ACE 400 comes stoc​k with a large, 8.5×11″ DD coil which is great for getting maximum depth, and covering more ground faster.

This large DD coil is perfect for covering large areas. It also will get great depth.

Does the ACE 400 have an adjustable ground balance?

No. The ground balance is set at the factory so you cannot adjust as you can on detectors like the AT Pro.

Because of that, I would not recommend this machine if you live in an area with highly mineralized soil.

Can this be used on the beach?

Yes, on dry white sand. However, this is a single frequency VLF detector, so it will not perform well in wet sand or saltwater since the salt will cause too much falsing and severely limit your depth. 

What is the price?

At the time of writing this article, the MSRP is $399.95. Note that is the MSRP, not the typical sale price when purchased online.

How much does it weigh?

The ACE 400 weighs 2.9 lbs with the stock coil. If that’s too heavy, consider purchasing a smaller coil to reduce some of the weight.

What kind of batteries does it take?

This detector uses 4 standard AA batteries which are included. They are not rechargeable but feel free to buy your own rechargeable batteries. Expect to get 20-30 hours of use time depending on your settings and if you use headphones or not.

The ACE 400 comes with 4 AA batteries already installed in the control box.

Are headphones included?

Yes, Garrett provides the ClearSound Easy Stow headphones. While these do the job, they are a bit cheapy in my opinion. It’s nice that Garrett includes these to get you started, but I would upgrade to a better pair in the future.

Is the ACE 400 waterproof?

Yes and no. The coil and poles are waterproof and submersible, but the control box is not. If you need a fully submersible detector, go with the AT Pro or AT Gold.

Where is it made?

Garrett makes all their metal detectors in the United States – Garland, Texas to be precise.

Does it have a warranty?

Yes. Garrett gives you a 2-year limited parts and labor warranty.

​Parting Words

I hope this article was helpful in determining if the ACE 400 is the right machine for you.

As I always say, you can’t go wrong with any Garrett detector. They are a quality brand and make very nice detectors.