Field Test by Ben Myers
(Reprinted with permission from Western & Eastern Treasures, July 2002, pages 42-48.)

Since Tesoro introduced the Golden µMax, detectorists have been using it to recover coins and similar targets from trash-laden parks. In this field test you will see how finding good targets among the bad is made easier with the ingenious features of the Golden µMax. Like its predecessors, the Golden Sabre and Golden Sabre Plus, the Golden µMax utilizes notch discrimination to zero in on the good targets while eliminating many of the bad. Additionally, four tones of audio target identification have been added to separate targets by pitch. This combination saves a good deal of time, requiring less adjustment of the DISC knob to identify targets and avoid many pulltabs. Since I first held a µMax metal detector, I have been amazed at the number of features that Tesoro is able to build into such a feather-light design. With a three-piece pole and "S" handle design, this 2.2 lb detector is made for hours of fatigue-free hunting and can even be carried in a backpack. Although it is possible to use the Golden µMax for nuggets and relics, I see its features best used as an effective tool of the coin hunter. Read further to learn more of this machine's controls and functions.

CONTROLS

The controls on the face of the small metal housing consist of four rotary knobs and two toggle switches with the headphone jack on the back. I found them very easy to access for finger-and-thumb manipulation. This means there's no need to stop hunting in order to make two-handed adjustments.

You will find that all but two of the controls are nearly "set and forget." This translates into less time fooling with controls and more time hunting. For example, even a new detectorist will have no anxiety about ground balance, as it is preset at the factory.

THRESHOLD, the top right rotary knob, sets the background hum prior to hunting and then is mostly forgotten.

SENSITIVITY, the next knob down, adjusts the amount of gain for depth of detection. Within a given area, this control will need little changing and is thus another "set and hunt" control.

Straight across the face is NOTCH WIDTH, which, when employed, is usually set to avoid a particularly troublesome type of pulltab. This setting will not likely change until you move to another location and encounter a different trash problem which you wish to avoid.

Located between the NOTCH WIDTH and SENSITIVITY controls is the NOTCH toggle, used to activate the notch to either a Wide or Narrow window, depending on the prevalent type of trash. The center position leaves the notch feature off.

The controls previously mentioned, once set, will get little or no adjustment during actual hunting. That brings us to the real "workhorse" controls, wisely placed by Tesoro at the bottom of the control panel where the finger and thumb can easily manipulate them.

The first of these is the MODE toggle with three positions. Extreme left does a battery check, the center position is Motion "All Metal" for auto-tuning, all metal or pinpointing, and the right position (DISC) is for Motion Discriminate Mode.

The other "workhorse" is marked DISCRIMINATE LEVEL. This rotary knob sets the 120 ED discrimination circuit for avoiding levels of trash targets.

Tesoro's well-planned design minimizes the number of control adjustments needed, then places those controls that do need more adjusting close to the fingers. Now let's take a more detailed look at those controls and what they mean.

THRESHOLD-With the Mode toggle set to All Metal, turn this rotary knob clockwise until a hum is heard. Next, back it off a bit, until you can just hear the tone. The mark on the knob will end up around the 1:00 o'clock to 3:00 o'clock area. Once it's set, you will be able to monitor what is going on beneath the coil. The response coming from the target will produce an audio tone; however, if the threshold is too low or too high, the changes in audio will be difficult for the ear to pick up. A deep or small target will produce a weaker signal that must cause the audio to increase enough to be heard. If the threshold is set too low, it makes it that much more difficult for the weaker signal to sound off. A barely audible threshold is generally the best one to use.

SENSITIVITY-As this knob is adjusted upward, the gain is increased to magnify the signal. Higher sensitivity means more depth of detection and the ability to locate tiny objects. But this capability comes with a price, as experienced hunters know. The best comparison I've seen is the one to driving in fog. In heavy fog (heavy mineralization) the high beams of the headlights (higher sensitivity setting) cause the light to reflect back into the eyes, resulting in poorer visibility (poorer operation and depth of detection). Often low beams (lower sensitivity) actually provide better vision in heavy fog (better detector operation in heavy mineralization). Additionally, too high a sensitivity setting can receive interference from outside sources such as power lines and other detectors close by. The best method is to advance this control until the detector begins to produce false signals (becomes unstable) and then back it off to the point where it just quiets down. The markings around the knob run from 1 to 10 and then into the Max Boost area. When mineralization for other interference is low, the Max Boost will allow even greater penetration into the soil for deeper targets.

DISCRIMINATION, NOTCH & NOTCH WIDTH-If you are plagued by a certain type of pulltab you will grow tired of digging them and turn the DISCRIMINATE LEVEL up to "Pull Tab" to knock out the signals. As you issue a sigh of relief with the quiet from eliminating pulltab signals, don't forget that this silence also represents a loss of signals from nickels and gold rings in the range from pulltab down to zero. Of course, this holds true for any metal detector with a normal discrimination circuit.

Tesoro enjoys a wonderful reputation for its discrimination circuits. Now they've carried it further with an added NOTCH window feature to save nickel-range targets from being rejected by the normal discrimination circuits. (The DISCRIMINATE LEVEL knob of the Golden µMax is marked MIN, IRON, Preset, PULLTAB, ZINC CENT, and MAX). In fact, the Golden offers an adjustable Wide or Narrow notch window.

If this is new to you, try to picture a horizontal scale of numbers from 0 to 100. This is a conductivity scale, and targets identify themselves along that scale by how well they conduct electricity. The detector's circuitry will measure each target's conductivity from its return signal. Although the target's identification can be altered by such factors as mineralization, corrosion, and other circumstances, they generally fall in around the same numbers. Due to a number of factors such as alloys used and size of object, gold jewelry can show up anywhere on the entire range of targets.

Now let's take that scale, which represents the normal discrimination line, and assign some numbers such as iron at 0, nickels at 28, round pulltabs at 32, zinc or Indian Head cents at 50, Wheat cents at 62, silver dimes at 64, silver quarters at 76, and a Kennedy half dollar at 82. Given that the numbers on the scale are not absolute, just look to see nickels at 28 and pulltabs at 32. With discrimination set at pulltab rejection, the rejected targets run from pulltab down through iron. Inside that range is a separate nickel area that also includes many gold rings (the nickels are not worth much, so gold is the real target). Utilizing NOTCH allows those "nickel" area targets to come beeping in, right along with highly conductive targets such as silver coins, while most pulltabs are eliminated.

Not content with just a nickel-range notch, the Tesoro folks also allowed for that Notch to cover a WIDE or NARROW window on the scale, and then added a NOTCH WIDTH control to adjust to suit your needs. In this way you can fine-tune your own notch width to decide how much trash to eliminate. Notice the toggle control to select either WIDE or NARROW, or OFF for no notch at all. Then notice the rotary knob called NOTCH WIDTH that further adjusts the size of the notch window. Thus, the detectorist can eliminate one particular type of pulltab or a wider range of targets such as pulltabs and screwcaps. The choice is yours.

MODES-As mentioned earlier, this toggle has three positions. If it is pushed to the left, the battery condition is checked: seven or eight beeps indicate full strength, while two or less means the batteries are low. It is a good idea to do a battery check at least ten minutes into hunting, after they have been under load.

The center position is ALL METAL. This mode will provide great depth, but of course will pick up all metals since no discrimination is used. It can be useful in beach and relic hunting or prospecting. In the old days, it was necessary to constantly hit a retune switch or button to adjust for drift due to changing conditions. The Golden µMax utilizes an automatic tuning, all metal mode to keep itself tuned.

This is also the Pinpoint position. I didn't think I would like this motion mode for pinpointing, compared to a totally non-motion, all metal mode, but was quite surprised to find that the Pinpoint function required just a tiny amount of coil movement. In fact, I found myself admitting that this VCO pinpointing (260 to 420 Hz) was actually easier to use than the totally non-motion Pinpoint. It detuned the target signal automatically, so that the center of the target was found quickly and easily, yet not so fast that target size could not be ascertained. Time and again, I was able to bring my coin probe right down on top of a coin at several inches. I have to say I was amazed that the Golden µMax had such precise pinpointing ability.

Note: Moving the coil front to back is just as important as left to right to pinpoint the location of the target (the shape of a cross). I also noticed that lightly pressing the coil to the ground over the target area revealed the exact center of the target.

By pushing the toggle to the right, you can place the detector in the Motion Discriminate Mode, the one most often used by most people. It requires very slow coil motion and provides the discrimination abilities (trash elimination) and audio tones needed to handle areas where trash can be a problem. The slow motion is a real help in trashy areas, to separate good targets from bad. This is a silent-search mode, so a threshold hum will not be heard.

TONE ID-As mentioned earlier, the Golden µMax provides additional tools for identifying targets in the form of tone ID. Although it is best known for the four-tone ID, there are actually six tones. The additional two are the "saturation tone" and a "rolling tone." The saturation tone has a double-beep sound to it. When you hear that, it means the target is near the bottom of the coil, depending upon the size, shape, and composition of the target. A large target near the surface can overload and cause problems with a target ID circuit. The saturation tone alerts the detectorist that a target is near the bottom of the coil, and that goes for coins as well.

I wasn't sure I would like this feature until I realized that I could use it to my advantage to determine target depth. On average, an ordinary size, current U.S. coin will give the double beep at 2-3". A dime can get a bit closer to the bottom of the coil than a nickel before causing the double beep. A person who gets to know the saturation point of coin targets can raise the coil for a normal beep to get a good idea of target depth. A large piece of surface junk like an aluminum can will still be sounding the double beep at the coil height where a coin goes to the single beep. I think you can see how this can be used to advantage in estimating target depth.

Now combine that information with the four-tone target ID and you will have additional information on what the target is before digging. The lowest tone (240 Hz) signals iron and smaller pieces of foil. The next higher pitch (315 Hz) is for nickels, larger foil, many gold rings, and some pulltabs. The second highest tone (370 Hz) covers more gold rings, most pulltabs, and screwcaps. The highest tone (500 Hz) sounds off for higher conductive targets such as pennies, dimes, quarters, and larger coins. You will find that most pulltabs fit into the 370 Hz tone, but some can also lap over into the lower 315 Hz tone. The reason is that manufacturers of pulltabs produce a wide variety in both size and composition to delight the detectorists.

IN THE FIELD

A number of school grounds and parks gave up a good number of coins to the Golden µMax during testing. The first stop was a school I had never seen before. It was one of those times where you just drive out into the country to see what is there. The first target was a clad dime at 4" that came through with a very strong, high tone. There was no doubt that it was a high conductivity coin. Further scanning had clad coins popping out with little effort. The Golden was pinpointing like a champ. A rusty iron ring produced the first "rolling tone," so I had to dig to investigate. After a few such items, I started to believe the detector and ignored such signals, as well as the low tones that always meant a nail at this location. After a run through the playground area, I headed up a slight incline until a high tone stopped me. From 3" deep came a target that made me laugh, a Disney key fob with a person's name on it-mine! I was flabbergasted to see the name Benjamin at the bottom. What are the odds of a detectorist finding a key chain with his own name on it? Heading back to the car, I walked a little to the right to cover the flagpole area. The poles were old looking, and I thought I might turn up some old coins to match them. Sure enough, a Wheat cent at over 5" gave a good, strong and high signal. Unfortunately, by then it was getting late, and there was no more time to check the area further.

The next trip was to a historic farm where I had gotten permission to search between the house and barn. Low tones indicated a good amount of iron in the ground. By the way, I often hunt with low or no discrimination, which produces more signals and information. At this location the iron signals did get to be a bit much, though; so I turned up the discriminator to knock them out. Near the barn I dug a toy Volkswagen car with a smashed-in roof and a shotgun shell nearby. My luck improved along the path between the house and barn, where I found a mercury dime at about 6" and two Wheat cents at about the same depth. The signals were good, repeatable ones. My best find at this location was made out behind the barn, where an Indian Head cent came to light. Silver is always nice, but there is something special about finding Indian Heads.

One weekend I went to a local park with two friends. Of course, they had to check out the Golden µMax and were quite impressed with its weightless feel. They were even more impressed when they saw a Wheat cent, Mercury dime, and Buffalo nickel after only an hour of hunting. In an area where people play touch footfall, a junk earring showed gold that turned out to be only gold tone, so that excitement didn't last long. Not far away a Susan B. Anthony $1 coin at a good 5-6" gave a strong, high signal. For some reason, I've been finding a number of these coins lately.

This part was a good test site, as there was an assortment of both good targets and junk in the form of pulltabs. Most of the tabs were the round type with the tab attached to the end of the ring. Coins near the surface gave themselves away with a high tone and double beep. Raising the coil an inch or so also told me how deep they were when the beep became a single tone. A slow, precise sweep over the target area gave good target separation. In mineralized areas a slow sweep is essential for good depth.

I was able to identify targets with a high degree of accuracy by noting where the signal started to break up or disappear as the Discriminate Level was raised. Most pulltabs were eliminated or just past the pulltab mark, while a signal disappearing at ZC CN (zinc cent) was usually a modern Memorial cent. Copper centers stayed in past this point, as they cannot be eliminated even at Max discrimination. The detector seemed to go especially deep for dimes.

In an area of the park where round pulltabs were quite a nuisance, it was time to use the notch discrimination. I didn't want to use the Wide Notch since the main pulltab type was always the same. By using Narrow Notch and adjusting the Notch Width just to eliminate the pulltab, metal detecting suddenly became much easier and quieter. Often, though, I would hunt at the preset discrimination mark, then flip the toggle from Off to Narrow to see if an interesting signal still beeped.

The final stop was at a school where the grassy back area ran into an adjacent part. Once again, clad coins were easily detected and pinpointed at various depths. A silver Roosevelt dime was found where bushes had been removed behind the school and a deep Indian Head cent in an older section of the park.

SUMMARY

There is much more to say about the Tesoro Golden µMax, such as the extra depth and wider sensitivity of the new concentric 9 x 8 coil and the latest microprocessor circuitry that makes everything work together. The fact that it only takes one 9-volt battery to provide 10-20 hours of detector operation should be mentioned as well. The Tesoro Golden µMax possesses a number of interesting features, but the most impressive are the target ID tones, the ability to set one's own notch width, the excellent pinpointing ability, and the famous Tesoro discrimination-all neatly packaged inside a super lightweight yet rugged design. Top that off with a limited lifetime warranty, and you've got one valuable coin hunting machine! When looking for a new metal detector, be sure to add the Golden µMax to your list of machines.