GOLDMASTER® Series
GMX SPORT
OWNER’S GUIDE
WATERPROOF GOLD DETECTOR
with XGB Technology
XGB TECHNOLOGY
XGB TECHNOLOGY is a patent-pending automatic ground balance
system. It is purpose-built for operating a high-frequency VLF gold
nugget detector in difficult ground conditions.
Traditional VLF detectors struggle to balance rapidly changing
ground mineralization and hot rocks.
With XGB technology, the GMX is able to track small changes in
soil composition as well as longer-term shifts in both ground phase
and strength. This allows it to operate in ground that traditional
VLFs struggle in.
Users have extended control over the range of XGB in the
Goldmaster’s All-Metal mode. Simply enable Iron Cancel to
expand the ground filter in moderate soils. In very challenging soil
conditions, hold the Iron Cancel button and select a higher setting
for maximum performance in variable ground.
SPECIFICATIONS
Detector Type Gold Nugget/Prospecting
Frequency 48kHz
Weight 4.0 lbs with batteries
Length 45 inches to 55 inches, Assembled
Batteries 8aa Included
Battery Life 20-40 hrs
Search Coil 6” Concentric included
IP Rating IP 68 waterproof to 10 feet
Audio Speaker or 1/4” Headphone
Ground Balance XGB and TracLock
Warranty 2 Year Transferrable
Unique Features Ground Scan, All-Metal Disc.
Optional Coils 4” x 6” GMX or 4” x 6” 24K
Introduction
White’s Electronics, Inc.’s Goldmaster® platform has served electronic prospectors
well over the last 20 plus years, resulting in income for professional miners and
diversion for hobbyists. With modern advances in DSP, improved ergonomics,
and performance increases, the GMX SPORT represents the next generation of
high-frequency induction-balance waterproof gold nugget detectors.
When our engineers set out to build the GMX, the goal was simple: Improve the user’s
chance to find gold by combining the electronics of the GM 24K with the waterproof,
rugged design of the MX SPORT.
The obvious way to achieve this goal is increased sensitivity. The GMX features a 54%
increase in coil voltage over the GMT. You will see this in increased sensitivity to small
nuggets. Even at lower gain settings the GMX is an extremely “hot” machine on small
gold and specimen nuggets.
Experienced electronic prospectors know that more sensitivity is not the only answer
to increasing the odds of success in prospecting. A machine’s ability to track and
cancel the ground is often the biggest challenge we face in our search for gold. That’s
why the GMX Sport features the all-new ground tracking system we call “XGB” (Xtreme
Ground Balance). This system works with multiple ground points to ensure stable operation. The GMX also features Iron/Hot-Rock cancellation in both audio modes, expanding the ground range even more for quiet operation in the most challenging ground.
When the nuggets are few and far between, prospectors often have more success
at sluicing, panning, or dry washing. You will find an all-new mode in the GMX, called
“Ground Scan” that can help you successfully track and mark black sand or other
mineral deposits in stream beds, washes, or even under ground (where the backlight
comes in handy).
In addition to these new features, old standbys like Variable Self-Adjusting Threshold
(vSAT), Ground Grab, TracLock, and adjustable audio options help users to setup the
machine as they see fit based on ground conditions and personal preference. Where
other companies rely on completely automatic operation for limited uses, White’s
Electronics, Inc. believes in giving you the ability to adjust a machine for a wider variety
of conditions, hopefully resulting in more gold in your pouch.
With a combination of patience, research, and a little luck, you’ll get your GMX’s coil
over gold. But be warned, if you don’t have gold fever yet you will after your first nugget!
Good luck and happy hunting,
White’s Electronics
Quick Start
Table of Contents
Assembly ............................................................................................................ 2
Batteries, FCC and CE Compliance ........................................................4
Interface ............................................................................................................. 5
Quick Start .........................................................................................................6
Special Notice .................................................................................................. 7
Controls
Sensitivity ....................................................................................................8
Volume/Threshold .............................................................................10
V-Sat ..........................................................................................................11
Target ID .................................................................................................. 12
Audio .......................................................................................................... 12
Iron Cancel/Discrimination ............................................................ 12
Gound Controls ..................................................................................... 14
XGB ............................................................................................................14
TracLock .................................................................................................. 15
Ground Grab .......................................................................................... 15
Ground Scan .......................................................................................... 15
Searching
Pinpoint Technique ..............................................................................16
Non-Motion Pinpoint Mode ............................................................. 16
Headphones ........................................................................................... 17
Field Use & Tuning .............................................................................. 18
Backlight & Battery Life .................................................................... 19
Hot Rocks ................................................................................................ 20
Sensitivity & XGB .................................................................................21
Pinpointing ..............................................................................................22
Sensitivity and Variable SAT ...........................................................22
Target ID .................................................................................................. 23
Frequency Shift ..................................................................................... 23
Proper Care ................................................................................................... 24
Service ..............................................................................................................25
Warranty ....................................................................................... Back Cover
Assembly
Search Coil
Non-metallic
Washers
Camlock
Fiber Bolt & Thumbnut
Fiber Rod
Center Rod
Search Coil
Cable
1. Remove all parts from the shipping carton and check assembly
diagram to ensure all parts are present.
2. Install black rubber washers on ber lower rod; attach search coil
to lower ber rod. Use only the nonmetallic washers, ber bolt,
and ber thumbnut provided to secure search coil loop to the
lower ber rod.
3. Insert lower ber rod into center rod so that the spring buttons
line up with one of the length-adjustment holes in the center rod.
Turn the camlock to eliminate any slack.
4. Insert the center extension rod into the hand-grip section. Turn
the camlock to eliminate any slack.
5. Wind the search coil cable around the rods, rst revolution over
the top of the rod, all the way to the display pod. Plug the cable
into the connector on the back of the display. When looking at the
back of the display, it is the connector on the right. Tighten the
retainer ring securely.
2
Control Pod
Display
Control Buttons
Velcro Armstrap
Camlock
Search Coil
Connector
Handgrip
Battery Holder with Cap
6. read the velcro arm strap through the slots on the armcup. With
your arm in position, fold the strap over onto the velcro so that the
strap is loose enough to to pull your arm in and out of the armcup.
7. Grip the detector and sweep the search coil over the oor. If the t feels
uncomfortable, adjust the position of the lower ber rod. e ideal
position allows you to stand up straight and sweep the search coil over
the ground without stooping over.
8. Install eight “AA” batteries in the battery holder carefully noting the +
& - positions marked inside the battery holder. Insert the battery pack,
lining up the contacts. Tighten the battery seal.
3
Tips on Batteries
• e GMX Sport operates for up to 40 hours (without backlight) using
eight quality “AA” batteries.
• High-quality “AA” alkaline batteries are recommended. Rechargeable
NiCad, Nickel Metal Hydride, or other similar “AA” substitutions work
well. Batteries near or above 2 volts per cell and higher are not recommended.
• Battery life will change with battery type, operating temperature, and
backlight use. Lowering the volume of the built in speaker or using
headphones extends battery life.
FCC COMPLIANCE
is device complies with part 15 of the FCC Rules. Operation is subject to the following
conditions:
1. is device may not cause harmful interference.
2. is device must accept any interference received, including interference that may
cause undesired operation.
Caution: Changes or modications not expressly approved by White’s Electronics, Inc.
could void your authority to operate this product.
CE COMPLIANCE
is device operates within the following frequency range and maximum power output:
1. Frequency band in which the radio equipment operates: 47kHz-48kHz
2. Maximum radio-frequency power transmitted in the frequency band in which the
radio equipment operates: 250mW
4
GMX SPORT Quick Start
GMX SPORT Interface
Target ID #
Higher number,
Better chance of gold
Beep Mode On
Iron Cancel On
Volume Level
SAT/Threshold Level
Audio Mode
SAT +/-
Volume +/-
Threshold +/-
Visual Target ID
Ground strength in
Ground Scan mode
Backlight On
TracLock On
Sensitivity
Power On/
Backlight
TracLock
Ground Scan
Off
Iron Cancel
Disc LO/HI
NOTE: Regular text = button TAP,
Adjust other settings
Ground Grab/Exit Setting Selection
Pinpoint (non-motion)
Italic text = button HOLD
Sensitivity
5
GMX SPORT Quick Start
Quick Start Instructions
With the GMX properly assembled and the batteries installed, follow
the instructions below to start nding those nuggets!
1
Turn the GMX on by pressing the POWER button.
Set the VOLUME to your preference (tap Speaker icon, use Up and
2
Down buttons).
Set the THRESHOLD to a faint hum (hold Speaker icon, use Up
3
and Down buttons). For silent search, turn this all the way down
Set the SENSITIVITY to a level that ensures smooth operation (Up
4
and Down buttons).
Set the SAT to get a stable threshold (hold Music button, use Up
5
and Down buttons).
6
7
8
9
10
6
Select your preferred AUDIO mode (tap Music button). With the
Music icon displayed you are in Beep mode. With no icon, you are
in
Zip mode.
Enable IRON CANCEL if you experience difcult ground conditions, hot and cold rocks, or iron trash (tap Nail button).
Lower the search coil to the ground, then “pump” the coil up and
down a couple of times and XGB will automatically balance or
track out the ground mineralization. Or you can Lock the tracking
(Lock button) and perform a ground grab (Bullseye button).
Start swinging the search coil in wide sweeps that overlap each
other.
If you experience false signals or constant beeping or popping,
turn the SENSITIVITY down a bit, adjust the SAT up, or enable
IRON CANCEL.
SPECIAL NOTICE
*
If you attempt to demonstrate or test the
GMX by waving targets in the air in front
of the search coil, it is ESSENTIAL to have
the GROUND BALANCE button in the
LOCKED setting.
This is necessary because when the GMX
is in the XGB setting, the search coil must
SEE ground while it is passing over the
target or it will think that the target IS
ground and will attempt to track it out.
This is the case whether you are demonstrating with or without Iron Cancel.
You may, however, demonstrate the fast
ground balancing feature of XGB or
GRAB by waving or pumping a mineralized rock in the air in front of the search
coil.
Thus, testing the GMX with targets while
in XGB mode must be done in or on the
ground.
7
GMX Controls
Controls
Current
Sensitivity
Level
Sensitivity
Increase
Sensitivity
Decrease
Sensitivity Control
With the SENSITIVITY control, you
increase the signal strength coming from
the ground. You might expect increased
signal strength to always nd more nuggets
at greater depths. However, high ground
mineralization will “bounce” the signal
back and mask good targets. It is therefore
necessary to ADJUST the SENSITIVI-
TY to give you the maximum allowable
SENSITIVITY without masking targets or
over-loading the circuit and at the same
time allowing you to operate the detector
with a constant threshold hum so that faint
signals can be detected.
This is where the GMX can help you out.
When ground mineralization is too high for
the current SENSITIVITY control setting,
the display shows you a series of lines
along with an audible “alert”. Reduce the
SENSITIVITY till the overload warning
ceases. On occasion, while searching, you
might go over a very large or very shallow
target. This will result in the same type
of behavior. Lifting the coil higher may
reveal some information on the target. You
still might want to dig it up!
Sensitivity Adjustment
1. The UP and DOWN buttons control the SENSITIVITY. Each press on the UP button increases from a minimum level of “0” to a maximum level of “10”. Please note that levels 0-9
adjust the system gain, and that setting 10 enables an Audio Boost for maximum sensitivity.
2. Average ground conditions will generally allow for settings of 5-7 on the SENSITIVITY
setting. In mild ground you may be able to run as high as 10, and in extreme ground you may
need to lower the sensitivity to under 5. If the GMX overloads, the sensitivity is set too high!
3. One way to look at the SENSITIVITY control is like the accelerator in your car. Sometimes
you have to ease off for better control, and other times you can go “full throttle” for maximum performance.
8
GMX Controls
4. The object of increasing the SENSITIVITY is to get the maximum available depth
from the detector WITH-OUT causing the overload message to appear, which indicates an overload of the circuit.
5. In addition, any increase in SENSITIVITY adjustment should NOT BE at the
expense of maintaining a smooth and constant THRESHOLD “hum”. False signals,
beeps and bops from bits of mineralization, erratic behavior, and lapses in THRESHOLD all can be the result of running with too much SENSITIVITY.
6. The use of the VSAT (variable self-adjusting threshold) control will also help to
maintain a smooth THRESHOLD “hum” and will be covered in a later section.
7. While using a steady slow search coil sweep speed, advance the control towards “10”
while maintaining a quiet smooth background THRESH-OLD “hum”. If ground
noises are still a problem reduce SENSITIVITY.
8. The TARGET ID capability of the GMX also functions more accurately when the
SENSITIVITY is set at a level which allows for smooth operation. Too much gain
can cause bad ground to distort the proper identication of iron and non-iron targets.
9. Just as a slow, broad search-coil speed will maintain smooth threshold, it will also
allow the search-coil to get clear off of the target with each pass, thus insuring that
the GMT “sees” ground as well as target. This is essential for the accurate operation
of Target ID.
With the right combination of sensitivity,
SAT, and patience, your GMX can nd
gold down to the sub-grain size
9
GMX Controls
Volume/Threshold Adjustment
The VOLUME control on your GMX only
adjusts the sound level of target sounds and
conrmation beeps. It is used in conjunction with the THRESHOLD to give you
the most control over the dynamic range
of you detector. This control is adjusted
by tapping the SPEAKER icon and then
using the UP and DOWN buttons to adjust
it louder or quieter. Note that holding the
SPEAKER button adjusts the threshold,
Volume,
Threshold
Level
Volume Adjust
(tap)
Threshold
Adjust (hold)
which will display the letters “th” on
screen. Adjust the THRESHOLD so you
can hear a faint hum - this will allow for
best performance on small targets.
For example, with a low THRESHOLD
and a high VOLUME, there is a large
range of signals you might hear. Some will
be just above the threshold, others will
bang out loud and clear. You can adjust
the VOLUME and THRESHOLD to your
own preference, but in general the best
range of target sounds will be available
with a high volume and low threshold. At
volume levels 9 and 10, you will see b1
and b2 on the display as these two levels
enable consecutive audio boosts for low
signals.
External Speaker or Headphones?
There are advantages to running your GMX with headphones. Battery life will be increased
and it will be much easier to hear the faintest signals. Wind especially can cause issues with
using the external speaker on a gold detector, as the buffeting in your ears can mask small
target sounds.
However, in snake country or in hot and humid conditions headphones may not be an option. The GMX has independent volume settings, meaning that you can adjust the volume
for the external speaker as well as the headphones, and these settings are saved when you
power the machine down. The GMX automatically senses when headphones are plugged
in, and the machine will switch to the saved headphone volume level. It then returns to the
saved speaker volume level when the headphones are removed.
10
GMX Controls
V-SAT Speed Control
The Variable SAT (Self Adjusting Threshold) Speed control adjusts the speed that the
GMX recovers its threshold hum when the
search-coil passes over changes in mineralization. This setting is adjusted by holding the
MUSIC button and then adjusting the SAT
up or down between 0 (off), 1 (medium), or
2 (fast). The letters “Sa” will display when
adjusting V-SAT.
SAT Level
SAT adjust
(hold)
Hot rocks are mineralized rocks.
They can be heard because they are different in mineralization than the surrounding
matrix or body of ground. Negative hot rocks,
such as magnetite, tend to give a “boing”
sound when the search-coil is passed over
them. The greater the difference between
them and the ground, the louder the “boing”.
Positive hot rocks, such as maghemite tend
to sound just like any other metal target,
such as a nugget and can give a zip-zip
sound. Positive hot rocks will test any prospectors patience. The GMX will reduce the
effect and help to identify many hot rocks.
V-SAT Adjustment
The Initial Setting is 1 (medium), appropriate for mild-to-moderate ground mineralization. When you encounter fast changes
in ground mineralization or deeper, larger
hot rocks, you may either get false signals
(positive ground) or lapses in the THRESHOLD hum (negative ground). Increasing
the V-SAT control setting to 2 will speed up
the auto adjustment of the THRESHOLD
“hum” and reduce this interference. At the
same time, you should slow down your
sweep speed to help SAT do its job to main-
tain a smooth threshold.
Remember, overall depth will be diminished
with a faster V-SAT speed, but if the ground
is too noisy to separate a good target from
a false signal, it is better to operate with a
little more V-SAT speed than to lose a target
altogether. This is the same logic that was
used in describing the SENSITIVITY control. Lowering the gain will reduce overall
depth, but by doing so you can also improve
your performance and nd more nuggets in
the long run. For best results, set your V-SAT
speed JUST high enough to cancel out false
signals from ground mineralization and
set the SENSITIVITY control JUST high
enough to maintain maximum depth without
having false or erratic behavior.
11
GMX Controls
Target ID
The GMX features two types of Target ID. The most obvious is the large numbers
displayed in the center of the screen when the coil passes over a target. These two digits
represent a scale from 0 to 99, with higher numbers equalling a higher chance that the
target is non-ferrous.
In challenging ground, or when gold is located in host rock, it’s important to dig every
questionable signal. Sometimes very small gold can produce a low Target ID number,
or in the case of sub-grain-sized nuggets, no number at all. This is why many electronic
prospectors hunt mostly based on sound.
In addition to this, the top most bar of the screen displays a general scale of targets. You
can see that gold has a large range, due to the many different sizes, shapes, and consistencies of gold nuggets. When in doubt, dig it out!
Target ID #
Higher number,
Better chance of gold
Visual Target ID
“Beep” Mode
Audio Mode
Selection
Audio Mode
Tapping the Music button toggles between two different audio modes. With the Music
Icon ON, the GMX will produce 2 distinct beeps, one high and one low, for different
types of targets. The higher tone has a better chance of being a non-ferrous target (gold,
aluminum, silver, brass, etc.), and the lower tone has a better chance of being ferrous
(iron, hot rocks, etc.).
With the Music Icon OFF, the GMX will produce a standard VCO all-metal “zip” sound
on targets. This mode is generally preferred by experienced prospectors due to the nuances of the sound and perceived sensitivity to small targets.
All settings (SAT, Volume, Threshold, Iron Cancel, etc.) have the same effects in both
audio modes. This allows for maximum exibility for different users.
12
GMX Controls
Disc Setting
(2 bars)
Iron Cancel
When detecting for gold nuggets it is often
best to “dig it all.” Gold can have various
shapes, sizes, be embedded in iron rock, so
it’s impossible to account for every nugget
in the ground and only dig gold. However,
in challenging conditions the electronic
prospector may need to adjust the GMX
to cancel out unwanted targets or heavy
ground mineralization. This is done at the
expense of some sensitivity, but in extreme
conditions the amount of signals can overwhelm your senses, causing “ear fatigue.”
In these cases the real battle is in nding
good targets, not raw depth.
Situations where you might need to use
Iron Discrimination are: rapidly changing
ground minerals, high concentrations of
hot or cold rocks, old mining camps with
iron trash, highly variable ferrous ground
conditions.
(Discrimination)
Iron Cancel (tap)
Disc. Adjust (hold)
Iron Cancel Adjustment
To enable Iron Cancel in either Beep or Zip mode, tap the Nail Icon. This will engage
the Iron Cancel feature at the default setting. You can adjust this setting up or down
by holding the Nail Icon, then using the Up and Down buttons to set the discrimination
range. Best practice is to only use what is required for smooth operation of the GMX, as
too high of an Iron Cancel setting will decrease the detector’s sensitivity to small gold
nuggets. Again, this is a trade off - it is up to the operator to pick the balance between a
smooth threshold and maximum sensitivity. If you are getting a lot of high signals from
hot rocks, tap the LOCK button while in the Iron Cancel adjustment mode. This will
block out a range of signals from 94-99.
Please note that unlike coin detectors, the threshold will not go silent over discriminated
targets in the “Zip” (all-metal) audio mode. This is to ensure smooth operation and combat ear fatigue. You may nd that it is best to detect with Iron Cancel off, and then toggle
it on to check a target. Very small gold will often report a very weak target ID number,
or none at all, so this setting is best used as a last resort in only the most challenging
conditions.
13
GMX Controls
Ground strength
Ground Controls
Gold is usually found in min-
eralized ground, and the GMX
has XGB enabled by default
when the machine is powered on.
This makes it easy to get started
prospecting, as the machine au-
tomatically cancels out unwanted
mineralization so you can focus on
listening for targets.
However, there are times when
you may want the option to LOCK
the ground balance control, or even
display the ground information on
screen. The comprehensive ground
options on the GMX allow you to
do both of these things quickly and
easily, without menu-diving.
Ground Phase
in Ground Scan
Ground Grab
in GroundScan
TracLock ON
TracLock ON (tap)
Ground Scan (hold)
XGB
The original Goldmaster® featured a revolutionary ground lter system that was quick
to respond to mineralization changes. But even this industry standard had its limitations.
XGB is the automatic ground tracking method used by the GMX, and features an all-new
method and algorithm thanks to modern processing speeds and updated Digital Signal
Processing. For users this means that they can use this detector in a wider variety of
ground conditions with more stable operation and less ground noise. When coupled with
the Iron Cancel and SAT settings you have a truly versatile set of tools to combat nasty
ground.
XGB is the default setting on the GMX, and recommended for most users in most conditions. It has the ability to track a wide range of ground, from ferrous to alkali, and features
an increased tracking speed over previous models without hurting sensitivity to small
nuggets. The arrows above and below the LOCK icon indicate whether XGB is tracking
up or down in values.
The algorithms used in XGB also give the GMX an edge due to the ability to track multiple ground points simultaneously. In highly variable grounds this is a huge benet, as
you may encounter wide enough swings in ground phase to render other machines almost
unusable.
Even though XGB is the suggested ground setting, advanced prospectors know that there
are times when more control over the ground settings can equal more gold in your pouch.
Details on these settings follow.
14
Controls
TracLock
TracLock on the GMX is the locked, “manual” ground setting. It functions similar to the
original GMT.
To LOCK the ground tracking to the current setting, TAP the LOCK button. A padlock
will display on the screen. This will put a hold on XGB and lock the current ground
phase and strength setting. This can be useful in those cases where you may nd extremely tiny gold, or when you have located a faint target. In some cases automatic ground
balance has the potential to track out tiny nuggets as you zero-in on your target. You may
nd it useful to enable XGB while searching, and then LOCK the tracking right after you
get a target.
Ground Grab
While the tracking is locked, you can press the CROSS HAIR button to perform a
Ground Grab. This updates the ground setting to what is currently under the coil. With a
combination of LOCKED tracking and Ground Grab you can easily update the ground
balance point as you swing, which serves as a sort of hybrid method of operation.
When you perform a Ground Grab the current ground phase reading will briey display
on the screen. This is a good way to keep track of the type of mineralization you are
walking over. More ferrous soils tend to produce a larger ground number, whereas more
alkali soils will produce a smaller number.
Ground Grab will also display the ground phase when the GMX is in XGB (automatic)
mode, but does not interrupt the automatic tracking processes.
Ground Scan
Ground Scan is enabled by holding the LOCK button. The display will change to display
the ground strength on the top bar, increasing from right to left. Full bars equates to
very strong mineralization, and one ashing bar alerts you that no ground information is
present.
The two-digit numbers displayed are the ground phase. Solid ferrite will read around 81,
alkali will read between 50 and 30, but you may encounter any range of phase numbers
depending on the area you are in.
Ground Scan is very useful in prospecting dry washes or creek beds for black sand
deposits. One trick you can use is to carry some landscaping ags with you, placing one
down where the mineralization is the strongest about every 10 ft. After making a pass you
can look back at the ags to identify the highest concentration of minerals. That is where
you would want to process material through a sluice or dry washer.
To return back to the regular search mode, tap the LOCK or CROSS HAIRS.
15
GMX SPORT Searching
Searching
Pinpoint Technique
Due to the wide scan nature of elliptical
search-coils it can be difcult to locate
small targets under the physical center
1 2
3
Again, the procedure is to sweep over the target from side to side noting the side to
side center (see step 1 in diagram). Then turn 90 degrees and sweep the coil side to side
noting the center from this new direction (see step 2 in diagram). “X” marks the spot that
you need to dig (see step 3 in the diagram). You can practice with a small pieces of lead
or gold on top of the ground to become acquainted with the technique. It’s a good idea to
have a magnet handy, preferably in the handle of your digging pick, to pull iron out of
the dirt pile. It will speed up your recovery time. It will work on small almost invisible
hot rocks too.
of the loop. Use an “X” marks the spot
technique as shown in the diagram to
identify the portion of ground the nugget
is in. Because most nuggets are too small
to isolate to an exact location as in coin
or relic hunting, remove the soil under
the center of the “X” until the target is no
longer in the hole, but in your pile of dirt.
Techniques for examining the pile of dirt
are discussed later in the manual. (page
20)
Non-Motion Pinpoint Mode
In addition to this traditional method of pinpointing, the GMX also features an all-new,
non-motion pinpoint mode. This is engaged by holding the cross hairs button (large button in the middle of the keypad). With this button held down the detector will sound off
on targets whether the search coil is in motion or not. Non-motion pinpoint mode disengages the XGB ground tracking, Iron Cancel, and SAT, so in very challenging conditions
you may nd that this pinpoint mode struggles to counteract mineralization. But it can be
very useful in sizing targets under the coil and giving you an idea of their shape. For example, nails can often pinpoint as an oblong shape with a stronger sound on the at head.
While in non-motion pinpoint mode the screen will display the signal strength using the
two bottom “swoop” segments as well as the two-digit numeric display. The numeric
display reads from 0-30, with 0 representing a target close to the surface and 30 a target
at the edge of detection. Due to the various size, purity, and mineral content of gold nuggets, this scale is not capable of giving absolute depth readings and should only be used
as a reference point for signal strength. It also may give strong readings for extremely
large iron items that can surprise you with how deep they really are. The opposite is also
true- very small nuggets may read as weak targets. So it is best to look at the readings
and sound of the non-motion pinpoint mode as a signal strength, and not a depth reading.
16
GMX SPORT Searching
Headphones
The headphone jack on the GMX is located on the rear of the battery box. There
is a dust cover for the headphone jack (in
your parts kit) that should be used when
not running headphones. Most prospectors
prefer high quality stereo headphones so
White’s has chosen to wire the headphone
jack for stereo. If you have a mono head-
phone, you can purchase an adapter that
will allow sound in both earpieces. Some
headphones come with a switch for stereo
or mono jacks.
In choosing headphones, make sure they have a VOLUME CONTROL. This is an important comfort and safety issue. Remember that you want the faintest THRESHOLD “hum”
possible but a strong comfortable target signal. With headphones you will be able to work
with a lower THRESH-OLD “hum”, hear fainter target signals, avoid bothering others
with a “beeping” box, and save on battery life. Many high quality headphones from full
ear enclosure to lightweight summer models that offer a bit more safety in snake and bear
country are available on the market. Higher impedance headphones (60 Ohms or greater)
give the most sensitivity and are better for hearing the tiny targets most likely to be heard
while prospecting. Properly balanced impedance is important as well as low distortion.
Headphone Volume
Since the GMX has a volume control (accessed by tapping the speaker button and adjusting the audio volume up or down), with an in-line volume control on certain sets of
headphones you have an added adjustment. This is due to the fact that the GMX’s volume
control only affects signal sounds, not the threshold level.
For a maximum range of audio sensitivity, a user would set their GMX volume at the
maximum level, and then adjust the in-line headphone volume to suit their preference.
This will allow for both very subtle, quiet signals as well as very loud signals, giving you
a wide range of target volumes.
For a more moderate range of audio sensitivity, a user would set their GMX volume at a
medium level and adjust the in-line headphone volume up. This will make quieter signals
seem a bit louder and give less dynamic range, which may aid in target acquisition for
some users.
17
GMX SPORT Searching
Field Use & Tuning Tips
Putting it all together:
Once you have achieved the initial ground balance, you are ready to start searching.
Move the coil just over the ground and listen for the distinct zip-zip sound produced by
a target. It is wise to plant a nugget just under the soil to practice on in order to learn
to recognize what it will sound like. If you don’t have a nugget, use a nickel or piece of
lead (sinker or bullet). A very shallow bird shot sounds just like a tiny piece of gold. You
can practice with different sized nuggets and at different depths. Remember, planting a
target disturbs the ground mineral, which usually reduces the depth it would have been
found in undisturbed ground. It will take practice to determine the proper search speed
and technique. Do not go too fast. Try to overlap your sweep path so that you won’t miss
the tiny and deeper nuggets. When you hear a zip-zip, perform the “X” pinpoint technique
or use the non-motion pinpoint feature (page 16) over the loudest portion and eyeball the
center.
Rather than concentrating on all of the controls of the detector, think of the detector’s
systems as an extension of your senses that are working together to tell you what is below ground. You will be tuning yourself to the search area. The SENSITIVITY, the GROUND
BALANCE, the VSAT speed, the THRESHOLD, the IRON CANCEL, all working together at
the same time. Soon the detector will not even be noticed and your senses will take over,
painting a mental picture of what lies below.
Dig ALL Metal Targets at first, then Reject Iron:
At first, dig all targets until you get used to the sound of various items. As with other VLF
detectors, a nail or oblong piece of iron laying horizontally will produce a double beep. A
“good target” is considered anything that is not IRON. You want to detect lead, brass,
copper, aluminum and silver. Any of these metals can simulate the sound of a gold nugget and must be dug. Keep a particular lookout for the tiny lead bird-shot so common in
mining areas. If you are detecting these tiny targets, you are doing everything right and
will eventually find gold.
Locked GROUND BALANCE tuning for very small nuggets:
While the XGB automatic ground balance makes nugget hunting easy for prospectors of
all experience levels, a LOCKED ground balance can greatly improve your odds of finding
gold in some situations.
The reason for this is simple - the smallest nuggets can produce only a slight threshold
raise, and often vary only a few phase degrees off of the ground due to their tiny size. If
small gold is your gold, locking the ground tracking allows those faint variances to push
through the ground balance point and create a target signal for the GMX.
However, in challenging ground conditions this is not always an option. This is where
using the Ground Grab feature is useful, as you can manually update the ground balance
at any point as you detect.
18
GMX SPORT Searching
Another option is to run the GMX in XGB mode, and after hearing a faint target signal,
immediately locking the ground balance. Now you can double check the target from
different angles without the XGB “tracking out” that target. This provides the best of both
worlds - automatic tracking but the option to freeze it after acquiring a signal.
If hot rocks are driving you crazy, you can also ground balance directly over the hot rock,
then lock the tracking. If the rest of the ground matrix does not give you a false signal
after doing this, you have successfully cancelled not only the ground but also hot rocks!
Backlight and Battery Life
With a short tap of the power button, the GMX’s backlight will turn on, giving increased
visibility in low light conditions. In bright sunlight it will not be obvious this backlight is en-
abled, so there is a light bulb icon to indicate the status as well (icon on = light on). This
light consumes a great deal of power so it is best used only when necessary, as it may
lower the operating time by 50%.This backlight is on for a few seconds when powering
on the GMX, but only to allow for those situations when the unit is turned on in total
darkness. It will turn itself off after a few seconds and the icon will disappear until the
backlight is enabled or the detector is powered back on again.
Operating the GMX in Extreme Mineralization: Thanks to the combination of XGB
ground balance, SAT, and Iron Cancel, the GMX is able to operate in a wider variety
of conditions than many other VLF detectors. However, it takes some knowledge of
how to use each setting to combat bad ground, and the differences between types
of ground. In very strong mineralization, such as heavy iron stone or serpentine, it will
be necessary to lower the sensitivity. There is enough voltage at the search coil to
cause the GMX to overload in bad ground, so take some time to find a good setting
for sensitivity before making other adjustments. To check the ground strength you
can enable Ground Scan by holding the LOCK button. Another issue you may run into
is highly variable ground mineralization. In these conditions you will not get an overload
response, but will have to contend with lots of false signals with your coil sweep. This
is a result of the ground phase shifting rapidly under the coil. The first step you should
take is to increase your SAT setting by holding the Music Note button, and then tapping
the Up button to set the SAT to a higher setting. This will allow the detector to adjust
more quickly to the rapid ground changes. As a last resort, enable the Iron Cancel fea-
ture (the crossed-out nail button). This will not allow those low-range signals to break
through the threshold in either audio mode. Only in the most extreme conditions should
you adjust the Iron Cancel (by holding the crossed-out nail button) to higher settings.
19
Problems from Low Ground Mineralization:
The GMX is designed to work in an environment of heavy iron mineralization. In some
instances there may be so little mineralization that the search-coil will never go quiet as
it approaches the ground. In other words, there never seems to be any change or only
a faint increase in hum as the coil is pumped. In this instance, lock the ground balance
(lock button) and perform a ground grab before detecting.
Hot Rocks
The ever-present “hot rock” has caused frustration with almost every electronic pros-
pector. Most large ones are on the surface and can be kicked aside when identified.
You will soon learn what they sound like. The “overshoot” or “boing” sound will soon
become familiar. XGB is really a good option when they are plentiful. We find it best to
tune to the majority of the ground matrix and learn what a “hot rock” sounds like. The
XGB of the GMX will recover quickly upon leaving the vicinity of a “hot rock” and will
remain sensitive to gold nuggets. Since there are different kinds of “hot rocks”, it is al-
most impossible to eliminate all of them with one setting. Some will be identified by the
Target I.D. system as if they were iron. In every instance, practice makes perfect.
Negative Hot Rocks:
Negative hot rocks are ones that sit below the ground balance point of the GMX. They
actually produce a null or no sound when directly under the coil, making a sound once
the coil passes them. This sometimes sounds like a “boing” when the ground mineral
and the rock mineral are far apart in mineral TYPE, making them easy to recognize. At
any rate, these are usually black or grey in color and usually magnetic. When hunting
in LOCKED ground balance, they can often be tuned out by performing a Ground Grab
right over them and then proceeding to search with the GMX “over tuned” to the
ground. When using this procedure, be sure to search slowly and keep the coil close to
the ground and level. This will eliminate the bother of such “hot rocks.”
In some parts of the world these specific types of rocks are called “cold rocks,” since
they ring up beneath your current ground balance setting. They are usually easy to
identify thanks to the “boing” sound and difficulty in pinpointing them. If the ground is lit-
tered with these negative hot rocks, not just an occasional one, the XGB will track near
the hot rock balance point, lowering the GMX’s response. You may be forced to dial in
more SAT speed and/or reduce SENSITIVITY to keep a workable THRESHOLD “hum”.
20
Positive Hot Rocks:
Positive hot rocks are usually red or various shades of red to almost black. They sit
above your current ground balance point. They are sometimes as small as BB’s and
sound just like nuggets. These positive “hot rocks” are difficult to tune out and ring up
very low on your Target I.D. scale. They actually give a positive signal like metal and that
is why they are so hard to differentiate. The XGB will track some of these out automat-
ically. Using a higher SAT setting can also decrease your GMX’s response to these
positive hot rocks. Using a Double D coil on the GMX will allow the detector to operate
amongst hot rocks better than a concentric. And as a last resort, the Iron Cancel fea-
ture should all but silence any remaining hot rocks.
Wet alkali washes can be extremely difficult to work due to the sensitivity of high
frequency gold detectors to conductive dis-solved salts and their similarities with the
responses of small gold. But you can use the same techniques for alkali as you use for
positive hot rocks.
Field Use & Tuning Tips
Adjusting SENSITIVITY with XGB:
If while searching with XGB you experience erratic behavior such as false signals or
constant beeping and popping, you may be using a SENSITIVITY level which is too high
for the ground mineralization. This is often the easiest thing you can do to increase
your ability to hear gold in bad ground. Simply tap the down button to lower the sensi-
tivity on your machine. Try searching again. Continue this until you can hunt without
having erratic signals. Your detector is cancelling ground mineral as you sweep, so you
may notice a slight fluctuation in the threshold hum as the various ground minerals are
tracked out.
Even though it may seem counter-intuitive, adjusting the sensitivity down in tough
ground conditions can actually increase your chances of finding a nugget. This is due to
the fact that your ears are an extension of the metal detector. Hearing one faint signal
against a smooth threshold is much easier than hearing a medium signal against hun-
dreds of smaller ones.
Even though the GMX comes with advanced features like SAT, Iron Cancel, and XGB,
don’t overlook the first step you should take on any outing - finding the right sensitivity
level for the ground your are walking over.
21
GMX SPORT Searching
Pinpointing or “X” ing the target:
In most cases, pinpointing is easily performed by merely “X-ing” or criss-crossing. You
can also use the new non-motion pinpoint mode on the GMX. The loudest part of the
target will be under the center of the coil, just as with any detector. After the approximate location of the target is determined, take a handful of soil and check the hole again.
Continue this process until the target is no longer in the hole, but in the hand. Try putting
the handful of soil in a plastic container (pan, tray, cup, or scoop). Passing the container
over the coil will determine if the target is really in it. If so, a series of separations will
quickly expose the nugget. This is called “the 50-50” process. You take half the dirt out
of the scoop, and pass it over the coil. If the machine beeps, it’s in the scoop. Dump the
empty dirt and repeat until you have the nugget in hand.
Handful Of Dirt:
Some prefer to pass the handful of dirt across the coil directly. Caution must be exercised
if this is done. The GMX is sensitive enough to pick up the salt in your hand and respond
with a signal. Try this with nothing in your hand and you will see how close you can
come to the coil using this method. One way around this salt sensitivity is to pinch the
soil in small amounts and wave only the ngers over the search-coil. The condition of
the soil - dry, wet, ne, coarse, etc. - will have a lot to do with the best method for you.
SENSITIVITY and VARIABLE SAT (Self Adjusting Threshold):
XGB compensates for common ground minerals in the area. The V-SAT control compensates for the consistency of that ground mineralization (accessed by holding the Music
Note button). The greater the degree of inconsistencies, the more SAT is needed to quiet
ground noise. If the THRESHOLD becomes too erratic or noisy, it might be necessary
to use the SAT feature and/or reduce the SENSITIVITY control. This noisy behavior
will make it difcult to recognize a true target (possible nugget) from pieces of mineral,
commonly referred to as “hot rocks.”
It is not wise to keep a high level of SENSITIVITY if the detector will not operate smoothly. If you have been operating your GMX at full sensitivity and you determine that this is
too high because either the threshold is erratic or the detector is giving false signals, always
begin by reducing the sensitivity to a more stable range. If this does not correct the problem,
start adding some SAT speed by holding the Music Note button and using the up arrow. If
this does not correct the problem, go back to the SENSITIVITY and reduce it a little more.
Any drop in SENSITIVITY below 7-8 will result in some loss of depth. Any increase in
SAT speed above the default setting of 2 will also reduce overall depth. However, every
ground condition has its optimum setting.
Overall depth is not the ultimate goal. Finding nuggets is! Unless your threshold is constant and as smooth as possible, and free from false targets which confuse the picture, you
will never be able to tell the ground from the gold.
22
GMX SPORT Searching
Overload:
The GMX will overload when the coil is over a large object or extremely heavy iron mineralization. Lowering the SENSITIVITY will usually cure a mineralized area, but will
not do much to eliminate a real target. If the overload seems everywhere it is probably
mineralization and lowering SENSITIVITY is essential.
Target I.D.:
The GMX has three different target identication systems. First and foremost is the audio
response. In the All-Metal (or ZIP) audio mode, the detector sounds off with a scaled
pitch and volume raise over targets. In Beep mode, the detector will give a high tone for
mostly good targets like gold, silver, brass, and aluminum, and a lower tone for targets
more likely to be iron junk. It also displays a Target I.D. number, using a scale from 0-99.
You might think of this as a “dig percentage” meter, with higher numbers being more
likely to be a good target to dig. There is also a Target I.D. Bar, which gives you a block
in the Iron, Gold, or Alloy ranges. Segments farther on the right of the screen are more
likely to represent good targets.
Misclassifying Iron:
The Target I.D. will consistently identify some types of Iron and Steel objects as non-ferrous, particularly at thin steel such as a can lid, very large pieces of iron, and small
solid pieces of iron like heavy washers. Because this is a gold detector, it was essential to
design it so that it would tend to call doubtful targets “non-ferrous” or “possible gold”. In
this way, eliminating the possibility of mistaking gold for iron.
Ground Scan mode tips:
Prospecting takes patience.There are certain areas where the gold is so ne that metal detecting is not an efcient recovery technique You can use the GMX’s Ground Scan mode
to track mineral deposits.This is excellent for dry washes, creek beds, and old channels
where you might want to process the dirt using a sluice, dry washer, or gold pan.
Hold the Padlock button on your GMX and the screen will show you the ground phase
(two digit number) and strength (top Target I.D. bar). Find an area likely to contain black
sand (and therefore more likely to have gold) and sweep the coil over the stream bed normally. Wherever the concentration of minerals are the strongest (Target I.D. bar fullest),
drop a marker. As you continue down your path you will end up mapping the pay streak
with your markers, giving you a lane to work with your recovery equipment. The sensitivity control works in this mode as well. If there is no ground present, the rst Target I.D.
segment will ash.
Frequency Shift:
If you nd yourself detecting with others, or underneath power lines, you may encounter
EMI (electro-magnetic interference). Turn your GMX off and hold the Iron Cancel button
while powering it back on. Select a different frequency, listen to see if the interference is
gone, and then power the unit off to save the setting.
23
GMX Sport Information
Proper care
Cleaning
• All elements on the GMX Sport are waterproof to a depth of 10 ft.
• The detector can be cleaned with mild soap and water.
Weather
• Do not expose your detector to the conditions of a car trunk during
winter and/or summer extremes.
• Protect it from direct sunlight during storage.
Storage
• When the instrument is not in use, make sure it is turned OFF.
• If you plan on storing your detector for long, remove the battery
holder from the instrument and remove the batteries from the hold-
er.
• Store the instrument indoors, in an area where it will be protected
from abuse. Over the years White’s has noted more service repairs
and physical damage, on units in storage than those experiencing
daily use.
Additional Precautions
• Avoid dropping your detector while attempting to set it down to
dig.
• Avoid using your detector for leverage when standing up from a
dig.
• Do not use any lubricants, such as WD-40, on any part of your
detector.
• Do not modify your instrument during its warranty period.
24
GMX Sport Information
Service
White’s reputation has been built on quality products backed by quality
service. Service before and after the sale is the cornerstone of our cus-
tomer relations.
Before shipping detector for service:
1. Contact the dealer where you purchased. There may be a quick, simple
x or explanation that will prevent having to send the detector in for
service.
2. Double check the obvious, such as batteries, and try the detector in
another area to be sure there is not interference.
3. Be sure to send all necessary parts with your detector, such as search-
coil, batteries and holders.
4. Include a letter of explanation about your concerns, even if you have
talked to the Service Center by telephone. Make sure you get timely
updates on your repair status by including your e-mail address.
5. Take care in packaging instruments for shipping and always insure
your package.
White’s Authorized USA Service Centers:
Centerville Electronics
9437 Main Street
Manassas, VA 20110
Toll Free 1-888-645-0202
e-mail: bobnpaul@centrevilleelectronics.net
centrevilleelectronics.net
White’s Electronics, Inc.
1011 Pleasant Valley Road
Sweet Home, OR 97386
Telephone: 1-541-367-6121
e-mail: repair@whiteselectronics.com
whiteselectronics.com
25
Warranty
If within two years (24 months) from the original date of purchase, your White’s detector
fails due to defects in either material or workmanship, White’s will repair or replace at its
option, all necessary parts without charge for parts or labor.
Simply return the complete detector to the Dealer where you purchased it, or to your
nearest Authorized Service Center. The unit must be accompanied by a detailed explana-
tion of the symptoms of the failure. You must provide proof of date-of-purchase before
the unit is serviced.
This is a transferable manufacturer warranty, which covers the instrument two years from
the original purchase date, regardless of the owner.
Items excluded from the warranty are non-rechargeable batteries, accessories that are not
standard equipment, shipping / handling costs outside the continental USA, Special De-
livery costs (Air Freight, Next Day, 2nd Day, Packaging Services, etc.) and all shipping /
handling costs inside the continental USA 90 days after purchase.
White’s registers your purchase when the Sales Registration is completed at: www.white-
selectronics.com/device-care/warranty-registration/The warranty does not cover damage
caused by accident, misuse, neglect, alterations, modications, unauthorized service, or
prolonged exposure to corrosive compounds, including salt.
Duration of any implied warranty (e.g., merchantability and tness for a particular pur-
pose) shall not be longer than the stated warranty. Neither the manufacturer or the retailer
shall be liable for any incidental or consequential damages. Some states however, do not
allow the limitation on the length of implied warranties, or the exclusion of incidental or
consequential damages. Therefore, the above limitations may not apply to you.
In addition, the stated warranty gives you specic legal rights, and you may have other
rights which vary from state-to-state.
The foregoing is the only warranty provided by White’s as the manufacturer of your
metal detector.
Any “extended warranty” period beyond two years, which may be provided by a Dealer
or other third party on your detector, may be without White’s authority involvement and
consent, and might not be honored by White’s Electronics, Inc.
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