Metal Detector Field Test & Review - Garrett ACE 400
By Joe Patrick
From Page 44
May, 2016 issue of Lost Treasure

Garrett Metal Detectors is on the move; with such recent highly-successful products as their Pro-Pointers™, AT Pro™ and ACE™ series Garrett precisely has their thumb on the pulse of the metal detecting hobby. When I see such great products, I realize that they do not happen by accident but are the result of accurate market research, cutting-edge engineering and quality manufacturing. As an example, Garrett’s ACE series of metal detectors - the 150, 250 and 350 - provide a rock-solid combination of comfort, ease-of-use, low cost and high performance. In other words, value!

I well remember the introduction of the ACE 150 several years ago. I and many others were simply astonished at how much metal detector you got for only $179.95. The entire ACE series provides that same kind of performance and value, plus more.

So with a solid foundation of ACE detectors already in place, Garrett has just introduced three more metal detectors to the ACE lineup… The new ACE 200, 300 and 400. This field test report is about the ACE 400.


The “Made-in-USA“ Ace 400 maintains the same yellow high-strength plastic and black powder-coated pole colors as all other ACE detectors, but the electrical design offers some significant new features to make the ACE 400 the current “flagship” of the entire ACE series.

First and perhaps most welcomed and significant, the ACE 400 now has a digital Target IDentification (ID) display on its front panel. Target ID (conductivity) is now prominently displayed in large ½” high digital numbers making precise Target Identification much easier to define. The two-digit numeric ID display ranges from 0 to 99 with iron and foil targets registering in its lower range and highly-conductive coins in its upper range.

A printed Target ID Legend, at the top of the screen, works in conjunction with the Target ID Cursor to indicate a target's probable identity. Ferrous (iron) targets will indicate on the left half, non-ferrous targets that are thin or have low conductivity will indicate in the middle, and thick or high conductivity targets will indicate at the right. The upper scale consists of twelve graphic segments (pixels) for Target ID. The lower scale, or notch discrimination scale, indicates the discrimination pattern. The ACE 400 will produce an audible target response for the segments that are switched on, and no audible response for those that have been switched off. The Target ID Cursor and Digital ID will always indicate all targets. The discrimination pattern can be adjusted by changing modes and/or using the DISCRIM and Accept/Reject (/X) push button.

Another great addition and feature of the new ACE 400 is the inclusion of Garrett’s Iron Audio™. This is a very accurate and useful feature of the ACE 400. Scattered iron objects in the ground can mask good targets and even create “ghost signals” that appear to be a good target. Garrett’s electable Iron Audio feature allows the user to hear discriminated iron (normally silenced) in order to know the whole picture and avoid being tricked into digging an undesired target. Please note that some Iron discrimination must be used for Iron Audio to work. Four selectable levels (notches) of Iron rejection are available.

In areas with high concentrations of iron, it is recommended to switch off Iron Audio. Otherwise, it may produce far too many signals. Then, if a target is detected that has a questionable or inconsistent response, switch on Iron Audio to check if it is iron.

To fully appreciate the additional information offered by the Iron Audio feature, try the following: Start with the ACE 400 in the Zero Disc Mode and pass the searchcoil over a crown-type bottle cap which is lying flat on the ground. Note that the target response is consistent with the audio of a good target. Then set some Iron Disc on, switch on Iron Audio and pass the coil completely over this target again. The distinctive Low-High-Low response now indicates a target that is unmistakably iron.

The new ACE 400 operates at a higher 10 kHz frequency to provide better sensitivity to low and medium conductivity targets, such as gold and lead. The detector’s Frequency Adjust feature allows users to easily toggle between four (F1-F4) slight frequency shifts to help eliminate interference from other detectors or electrical power sources.

The ACE 400 has the typical S-pole assembly but now comes with two pole camlocks for better stem stability. The 3-piece adjustable stem can be “broken down” for easy portability and storage. The total breakdown length is only 24”. The S-pole includes both a padded hand-grip and adjustable arm cuff with adjustable strap and a built-in detector stand that can also be slightly adjusted to match a user’s forearm length.

Garrett’s 8.5” x 11” PROformance™ DD submersible searchcoil is used. This coil design provides increased detection depth and good target separation ability in high-trash areas. Blunted front and rear coil ends enable detecting closer to walls, fencing and other obstacles and helps minimize detector rollover when placed upon the ground. Optional searchcoils are available.

Any headphones with a 1/4” plug can be inserted into the jack at the rear of the Control Housing. Garrett’s ClearSound™ Easy-Stow headphones are included with the ACE 400.

The headphone jack is located at the rear of the control housing. I acknowledge that it is easier to manufacture the detector this way, but I would much prefer the headphone jack be located at the rear of the arm cuff/stem assembly similar to what the Garrett GTI 2500 has. Of course wireless headphones are the ultimate and after using them you may never want to go back to wired phones again! I wish that all metal detectors had wireless headphones!

The ACE 400’s total weight including batteries, coil cover and environmental cover is about 3 pounds. I found the balance to be just slightly “nose-heavy” due to the larger searchcoil used.


The ACE 400 is powered from 4 “AA” batteries. A front panel display icon shows their “real-time” status with 4 bars indicating full capacity and 1 bar indicating it’s time to change. You can expect 20 to 40 hours of operation depending on battery type and quality.

To power-on the detector, press the ON/OFF Power touchpad once. Press and hold for 1 second to power off. If needed, a factory reset may be accomplished by pressing and holding the Power touchpad for 5 seconds.

The ACE 400 has three distinctive pulse-width modulated audio tones based on target conductivity. Targets in the ID range of from 0-32 produce a low tone. Targets in the 33-75 range produce a mid tone and targets that register 75 and higher produce a high belltone. Pulse-width audio provides sharper, more responsive audio. I like belltone audio well enough for coin shooting the parks, but it would be nice to have the option to disable it as there are times when I prefer a standard audio tone, such as when relic hunting.

Discrimination and Notching is controlled with 12 unique accept/reject discrimination notch blocks. Black blocks indicate accepted targets and no (clear) blocks indicate rejected targets. The Target ID Cursor and Digital ID show all targets, accepted and rejected, but audio is only heard for accepted targets. The ACE 400 features twice the iron resolution of an ACE 250 to help separate good targets from adjacent junk iron even better.

Five selectable operating modes pre-set the ACE 400’s discrimination: Zero-Disc, Jewelry, Custom, Relics, Coins. Changes can be made to any of these modes but the detector only remembers those made to the Custom mode. On Power-up, all modes return to their factory setting, except for the Custom mode which “remembers” any discrimination changes previously made.

The Sensitivity setting has 8 levels of adjustment to suit most any site or ground condition. A rising bar-graph icon on the display shows the current level selected. Coin depth indication ranges from 2 to 8+ inches in 2 inch increments and is only accurate for coin-size targets.

The ACE 400 has pushbutton electronic pinpointing for faster and more accurate target location. “PP” shows on screen and audio and pinpoint bars on screen increase to indicate target center. You can also pinpoint off of the tip or tail of the searchcoil or do the “wiggle” method of pinpointing by quickly moving the searchcoil back and forth until the loudest and most consistent audio is directly beneath the searchcoil’s center. These techniques can be viewed in the ACE 400 training video on Garret’s web site.

Field Use

After reading the owner’s manual and watching a few online videos, I was very much looking forward to trying-out the new ACE 400! I decided to visit a large local park due to my success in locating many older silver coins there in past years; though today, sad to report, it’s a real challenge to find any silver and the huge amount of accumulated trash makes detecting difficult. But I know there are still many coins and items masked and hiding near and beneath this trash.

A few months ago, I searched this same park using a different brand of metal detector. I was digging a lot of iron, and in particular, steel “crown-top” bottle caps that the detector was unable to discriminate properly and was “solidly” indicating to be coins. So I was very curious as to how well the ACE 400, with its Iron Audio, could handle the same task. Iron Audio allows the user to hear discriminated iron and to alter the detector’s mid-tone signal range. This helps the operator hear the iron content in flat steel objects like bottle caps and washers that often trick a detector into reporting them as good targets.

The ACE 400 was very easy for me to get used to. I found the discrimination to work very well and especially when Iron Audio could be used to identify iron targets. In actual field use, I found the printed target ID display legend to be a bit too small for my eyes, so I relied on the digital ID numbers mostly for target identification as they are much easier to see. It didn’t take me very long to learn what targets the various ID numbers represented.

My first trip out found me at an old picnic grove in the park where I and others have found many coins and items over past years’ searches. I elected to use the Coins mode due to the high trash-density and increased the Sensitivity slightly when possible. The ACE 400 effortlessly help me “cherry-pick” through the trash and after 6 hours of searching I had a silver 1939 Washington quarter, 1943 Mercury dime, several Wheat cents and a handful of clad coins for my effort. It is interesting to note that I did not dig a single bottle cap, unlike the previous trip using a different brand of metal detector. I found Iron Audio to work extremely well!

Due to much rain during the several weeks of my field test my second trip out was to a local, 1960’s-era playground/baseball field close to where I live. Because I was mainly searching for newer coins, I used the same program and settings as before. The ACE 400 “nails” coins with ease and I like its distinctive belltone audio sound for coins. I found a big handful of clad and some modern nickels on this trip and very little trash! The included Garrett Environmental Cover-up was field-proven on those misty, rainy-day outings to be a welcome and useful accessory item providing first-rate protection from the light rain and mud on my gloves.

Another point that I almost failed to mention is that the ACE 400 has non-VCO modulated pinpointing audio. This has always been my preferred type of pinpointing audio on any detector I own and use. I personally do not like VCO audio! Every person is different and has his or her own personal preferences. Perhaps it’s due to the many years that I used a Garrett ADSII detector when I first started-out back in the early 1980’s. It had modulated non-VCO pinpoint audio.

The ACE 400 can de-tune a target during pinpointing by quick, successive pushes of the Pinpoint button. This will detune and shrink the target’s audio signal making the target sound smaller and much easier to center prior to retrieval.

The final site visited during my field test is a very old, circa 1700’s location, where I and my detecting friends have found many old coins and artifacts over past years’ hunts. Most coins found there have been from the mid to late 1800’s and early 1900’s. The location has been extremely hard-hit for years as all of the local detectorists know about the site and its history.

I decided to use the Relic program and “push” the sensitivity up as high as I could. I was digging just about any good-sounding signal I could hear. This is a truly “pounded” site and I knew the odds were slim of me finding anything good.

As sometimes happens, my best find of the day was my first. I was scanning the ground around an area that the boy scouts had recently cleared to make a large fire circle when I heard a clear bell tone 83-84 signal. Digging to a depth of about 8”, I saw the glint of silver. As I gently pulled it from the earth I could see it was a Barber dime. Upon a light cleaning, I could see that it was an 1898-S. For the next few hours I did not find much, just a modern nickel, one wheat cent and an old coal mine tag. But that single silver dime recovery made it all worthwhile!


Garrett has truly done their “homework” on the new ACE 400! It is an enjoyable, easy to use, productive and high-quality metal detector who‘s accuracy and performance will most definitely impress beginning and serious detectorists alike. It is lightweight and comfortable enough for those all day hunts and its feature-set enables and compliments almost any site or type of metal detecting chosen. Garrett recommends the ACE 400 for coin hunting, jewelry hunting, relic hunting, competition events, dry beach/freshwater hunting. I can well-vouch for its coin-hunting ability!

To fully appreciate the care, dedication, employees, engineering and staff who make Garrett metal detectors and especially the ACE series, please take a moment to watch this excellent factory-tour video courtesy of the MD-Hunter™ web site.

The ACE 400 lists for $399.95 and is covered by Garrett’s 24-month warranty. Accessory searchcoils are available to fit a wide range of treasure hunting applications.

The ACE 400 comes complete with Garrett’s ClearSound™ Easy-Stow headphones (with in-line volume control), an environmental control-box cover, 8.5” x 11” searchcoil cover, owner’s manual, warranty card and 4 “AA” Alkaline batteries. Everything you need to get started and out the door!

For additional information on the new ACE 400 or to request a copy of Garrett’s product catalog please contact: (972)-494-6151 or Garrett Metal Detectors, Inc., 1881 W. State St. Garland, TX 75042, Web: Email:

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