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Frequently Asked Questions & Answers On Metal Detecting & Metal Detector Choices
How Do Metal Detectors Work?
Illustration 'A' shows a typical metal detector user. He has followed the instructions supplied by the manufacturer and has his metal detector turned on. After testing his detector on some surface targets (coins) to make sure it is working, he now starts searching for buried coins and treasures.
Notice the "red" signal pattern being transmitted from the search coil into the ground. (Note: we have enlarged the illustration of the signal pattern for easier understanding). As long as the signal entering the ground does NOT come in contact with metal, there will be no audio signal, no flashing light, no vibration, nothing will happen.
Illustration 'B' shows what happens when the detector user's metal detector search pattern comes in contact with metal objects, in this case both shallow and deep coins. When the search pattern touches metal it interrupts the transmitted signal and this interruption or disturbance of the search pattern will cause the metal detector to alert the detector user (you) with an audio signal, usually a distinct loud sound. In some cases flashing or blinking lights will accompany the audio signal.
Simple isn't it?
Can one detector really do it all?
Most detectors are designed to excel at one type of hunting or another but can be used for other types of hunting as well. For example, most gold prospecting machines use some form of higher gain in the circuitry to get better sensitivity to small gold nuggets in the ground. While this is a good thing for prospectors, coin hunters may find it annoying that their detectors are picking up every bit of a pull-tab that has been run over with a lawnmower.
The art of metal detector design is the art of compromise. By accenting certain characteristics of any detector, you take away from other features. Any detector that does it all may not work as well for certain very specific treasure hunting. Talk to as many people as is possible and be realistic about your hunting needs. Finding a detector with the features that will best suit your hunting style is the most important choice you can make when deciding on a new detector.
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What is the best metal detector?
This is probably the #1 question that I get asked. Unfortunately, there is no one single answer. Each metal detectorist has specific needs that cannot be answered by one single detector. The easiest way to find the "best" detector is to evaluate your detecting style, your experience level, and the time that you will spend hunting. After taking all of these things into consideration, then you will be able to find a detector that fits your needs and your budget.
How much better is a $1000 detector than a $200 detector and in what ways?
The answers to these questions are connected, so I will try to answer them together. Generally speaking, the higher the price of a detector, the more features that it will have. More features translate into more knobs. The more features and/or knobs that a detector has, the more you are able to tune the detector to the type of hunting conditions that you are likely to encounter.
Will metered detectors find coins deeper than non-metered?
The use of a meter on a detector is no longer any indication of its depth capabilities. When metered machines were the top-of-the-line machines, engineers matched the detectors with the best possible circuitry. With the advent of more cost effective digital signal processing and LCD displays, there are a number of units available that are inexpensive and have meters. While these detectors have acceptable depth, there are plenty of other machines that have better.
The main thing to remember is that a metered machine will give an accurate audio signal on a target much deeper than an accurate meter reading. Air tests are a good indication of the ability of any display-type detector, but once the target is in the ground, there are several variables that may come into play affecting the reading. The most common is the fact that pull tabs and gold rings fall into the same area based on the mixing of alloys. The orientation in the ground can also cause some confusion for the detector. If you choose to get a metered machine, dig any target that gives a good audio signal regardless of the meter reading. You may dig up more trash, but in the long run, you will find more desirable targets.
Is a crystal-controlled detector better than one that is not crystal-controlled?
Most manufacturers use crystal resonators in their machines because of the tight tolerances of the resonator. If the part is listed as 15.7 kHz, all parts will be exactly that frequency. The downside of these super tight tolerances is that the detectors are more likely to crosstalk with each other. In other words, transmitted and received signals from two or more different machines will start interfering with each other.
Tesoro detectors use an LC or tank circuit to generate operating frequency. A capacitor and an inductor are paired together and create a naturally occurring efficient frequency. Variation in the capacitor and inductor cause slight variations in the operating frequency, which reduces the likelihood of crosstalk with other Tesoro machines. The variation is small enough that it does not affect the performance of the detector.
Are multi-frequency detectors better than single frequency types?
The tank circuit described above generates a sinusoidal or SINE wave form. The SINE wave is efficient to generate and has no harmonics.
Two frequency machines may combine a pair of SINE waves but are more likely to use a square wave.Multi-frequency machines almost always use a square wave or modified square wave. Square waves are rich in harmonics and take more battery power to generate. Harmonics generated by a square wave can be counted as individual frequencies and can be used to give more information as to target type and depth.
Why are there so many types of search coils?
There are two main types of search coils currently on the market—the concentric and the wide scan. The concentric coil uses two round antennas, one inside the other. This coil is used on most detectors that are designed for coin, jewelry, and relic hunting. Concentric coils discriminate very well and pinpoint very easily due to the fact that the strongest signal is always in the center of the coil. Wide scan coils use two D-shaped antennas that are placed back to back. Because of this configuration, they are also called "double-d" coils. The wide scan coil is less affected by mineralization than the concentric, so it is generally used for gold prospecting or relic hunting in bad ground. Pinpointing is done with the heel or toe of the coil. After determining the type of coil that is best for your type of hunting, the next thing to consider is the size.
There are many different sizes of coils available and each one may fine tune your hunting but only if you get the correct size. Larger coils go deeper than smaller coils but only on larger targets. When using a large coil, you may lose sensitivity to small targets. A large coil is also more susceptible to masking. Masking happens in the Discriminate mode when a good target and junk target are both under the coil at the same time. If the targets are close enough together, the bad target will be discriminated out, and at the same time, the detector will not be able to pick up the good target. Masking is very common in junky playgrounds and in-and-around old house sites.
Smaller coils will concentrate the signal and make the detector more sensitive to the little targets. Unfortunately, smaller coils tend to lose depth when compared to their larger cousins. Being that these coils don’t have as wide a search pattern, they are also less likely to mask targets in trashy hunting situations.
Knowing where you are going to hunt and what you are hunting for will go a long way in helping you choose the right coil for your needs. A larger coil is needed when hunting in a clean area or when hunting for relics that may tend to be deeper. A small coil will help find the smaller targets such as gold nuggets or fine jewelry or can be used when coin & jewelry hunting extremely trashy sites.
What is the difference between a wading coil and a regular coil?
When hunting in water, most coils tend to float. As customers want lighter and lighter coils, most manufacturers will fill coils with some type of foam or other lightweight hollow material. This naturally creates air pockets inside the coils and tends to make them float.
A wading coil is filled with one or more materials that have neutral buoyancy when placed in water.This keeps the coils from either floating or sinking and makes water hunting easier for the detectorist.
Are aftermarket "hot" coils that are advertised any good and why don't the manufacturers make them?
If you look closely at the advertisements of most so-called hot coils, you will find that they are slightly larger than the stock coils that they are replacing. As noted above, a larger coil may go deeper, but it has other drawbacks that may make it unsuitable for your particular style of hunting. Most manufacturers already make coils that are larger than the stock coils. These coils are specifically designed by the company engineer to match the circuitry of the particular unit that you are using.
How deep do detectors go?
The answer to this question comes in two parts. The first part has to do with the detector circuitry and coil design. Environmental factors make up the second part of the answer.
Coil and circuitry design determine the overall ability of a detector to find targets. During the design phase of any detector, the engineers decide which features to include. The things that they consider are the type of hunting and who will be using it. A beginner's model may not have the bells and whistles of the more professional models, but it will be easier to use. The more specific a detector's design, the narrower set of features it will have. Some detectors designed for The ultimate depth will be hard for a beginner to use or may be too sensitive to use in trashy areas. Coil size will affect the depth of the detector but may not be suited for a particular type of hunting.
Environmental factors include just about everything except the detector and coil. Just a few of the things to take into consideration are the following: size and shape of the target, soil conditions, orientation of the target in the ground, content of the target, and any outside interference, such as electrical wires and radio or cell phone traffic. Weather conditions, such as rain-soaked ground or even an incoming thunderstorm, may also play a part in the depth and sensitivity of any detector.
With all that being said, an average detector using a stock coil in moderate ground should see the following targets with these ranges:
Target Size Depth
Dime to nickel: 4 to 8 inches
Quarter to half dollar: 6 to 12 inches
Dollar to fruit jar lid: 8 to 16 inches
Knowing your detector and using it properly are the two most important things that you can do to get the best depth and sensitivity out of any machine.
How do you set up and use a metal detector?
Whenever you are using a detector, comfort should be your primary goal. A detector that is easy and comfortable to use allows you to be in the field longer and to find more targets.
The shaft of the detector should be adjusted so that the search coil is just off the ground when your arm is in a natural and relaxed position. Your hand should be lightly on the grip and your elbow straight but not locked. This initial setup allows you to swing the detector with an easy shoulder movement. The coil should move in an approximate three foot arc in front of you. This is called the sweep. While sweeping your coil, try to avoid swinging from the elbow.
How do I know where to dig?
Once your detector beeps, you have to pinpoint your target. Pinpointing your target is a skill that is very important to practice and learn. The faster that you can locate your target, the more time you can spend searching for treasure. The technique for pinpointing varies depending on the type of coil that you are using. But the basics are the same.
"Xing" the target with your coil is the most common type of pinpointing. To "X" a target, run your coil over the target and make a mental note of where the audio signal is the loudest. Start with your normal right to left sweep to find the loudest audio signal. You should shorten your normal sweep down to about two to four inches. Once you have a good idea of where the target is, run the coil 90 degrees over the target to tighten up the pinpointing. You can do this one of two ways. First, you can physically step to the left or right of the target so that the coil goes over the object using a normal sweep but turned 90 degrees. Second, instead of stepping to the side and sweeping the coil left to right, you can push and pull the coil forward and backward over the target. Try using both methods to find the one that works best for you.
Pinpointing with a concentric coil: Most coin and relic machines use a concentric coil. These types of coils pinpoint in the physical center of the coil housing. Most concentric coils will have a hole in the center of the coil so it is easier to make the mental note of the location of the target.
Pinpointing with a wide scan or double-D coil: The wide scan coil is slightly different from the concentric coil. By design, there is no center spot on the coil but a center strip of pinpointing area. The best pinpointing method is to use the very front of the coil or toe or the very rear portion or heel of the coil. Once you have gotten the signal, back the coil away from the target and use the toe of the coil to find the best signal. Pinpoint in the usual manner after that. To use the heel of the coil, push the coil past the target and use the end of the coil closest to you for the pinpointing.
Regardless of the type of coil or the pinpointing method that you feel most comfortable with, practice will make you a better pin pointer and save you time and effort in the field. How much discrimination should I use?
In the late sixties and early seventies, as metal detectors became more popular, most of them on the market were all metal machines and could not discriminate any junk targets. As detectors became more sophisticated, the ability for discrimination got better and better. Now coin hunters can knock out the junk targets and keep the good ones in, or so they thought.
Metal detectors judge targets based on their conductivity. Iron and silver targets are easy to separate because they are on opposite ends of the conductivity scales. However, the real struggle comes in the area of nickels, pull tabs, and gold rings. All of these targets are in the same area on the conductivity scale and can change due to the size, shape, and alloy of the target.
For most coin and relic hunting situations, I recommend a setting just high enough to knock out the iron and foil. This allows you to get all of the other valuable targets without fear of having them discriminated out.
How do I set my Sensitivity control to get maximum depth?
The Sensitivity control on most detectors is used to set the trigger point of any signal. The higher the Sensitivity setting, the smaller amount of signal a target needs to produce to have the detector give an audio signal. A very small or very deep target will not produce the amount of signal that a large or shallow target will. By increasing the sensitivity, the machine will give an audio signal to the smaller and deeper targets, but the detector may become too sensitive and start picking up ground effect or outside interference such as electrical lines or radio frequency noise.
The easiest way to set your Sensitivity is to turn it up until the machine starts to chatter. When the machine chatters, turn the Sensitivity control back until the chatter just goes away. This will give you the maximum sensitivity without any excess noise. If you can turn your Sensitivity control wide open without chatter, leave it there. Your machine will be operating at its maximum power capabilities.
What is ground balancing?
Ground balance is a form of discrimination that cancels out the effect of mineralization. Ground balancing is the physical act of finding the balance point where the effects of the ground are neither too positive nor too negative. When a detector is set with a positive ground balance, it will react to the mineralization matrix just like a target. When this happens, you will get an audio signal and targets in the ground will be masked by the mineralization. If a detector has been set up with a negative ground balance, the detector is discriminating out the ground and will go silent. A severe loss of depth and sensitivity are the results.
Finding the balance point between these two extremes is very important for the best operation of any machine. Most factory preset detectors are set just slightly positive. This will allow the user to work different types of soil conditions. A slight positive setting will also keep the detector from reading small ripples in the dirt and the hole you are digging to retrieve a target.
What is the difference between Preset, Manual, and Automatic Ground Balance?
All VLF-style metal detectors have some form of ground balance or mineral rejection. This keeps the detector working as close to its peak as possible and not be affected by mineral masking. When reading literature on all of the detectors, it can be confusing as to what the detector is actually doing.
Factory preset is the most common type of ground balance. It is used on most machines that are called "turn-on-and-go." The ground balance is set internally by a technician at the factory. It will work fine for most coin, jewelry, and relic hunting needs almost anywhere in the world. Factory preset does not require the user to do anything to set the ground balance.
Manual ground balance is used on detectors designed to work in highly mineralized conditions. The ground balance is set by the user and is tuned to the local ground conditions. In bad ground, a manual ground balance can give you better depth and sensitivity than a factory preset. Unfortunately, if the ground balance is set incorrectly, a loss of depth and sensitivity will result. When working with a manual ground balance, constant attention is a must. If the ground conditions change, the detector must be returned to the ground matrix to ensure the best operation of the machine. Manual ground balancing is a learned skill and must be practiced for best results.
While manual and preset ground balance are pretty clear, automatic ground balance causes some confusion. In the earlier days of metal detecting, any machine that was not a manual ground balance was referred to as an automatic ground balance. The term was used because the detectorist did not have to tune the machine; it was "automatic." In the late 80s, several detectors were introduced that had microprocessor controlled ground balance. That is to say that the detector sensed the ground condition and reacted to change by adjusting an internal electronic potentiometer. True automatic ground balancing had arrived. Some manufacturers and dealers still use the automatic title for factory preset machines. If you have a question about whether or not any detector is truly an automatic ground balance or not, check the machine with a mineral sample. If the machine actively tunes to the sample, it is an automatic.
What is the best type of ground balance?
This is another question that involves an honest evaluation of your detecting needs. Most detectorists who hunt a few hours here and there for fun or those who are novices would probably benefit from a preset type of machine. There are fewer knobs to worry about and the setup time is very short. This means more time swinging the coil and more chances of finding targets.
The more advanced detectorist or one who is hunting in much mineralized soil (gold prospecting or relic hunting) should get some form of adjustable ground balance. Manual ground balance is good for the avid hunter who wants to be able to tune the detector to his exact specifications. Depending on ground conditions and personal hunting habits, a slightly positive or negative ground balance can help the detectorist find targets. An automatic ground balance will always tune to its programmed parameters and can't be fine-tuned to the user's specifications.
Matching your detecting style and hunting habits to the type of ground balance of the detector will result in better finds.
How do I set up a manually adjusted ground balance detector?
Most manually adjusted machines are easy to set up, once you have practiced the skill necessary. Start with the machine in the All Metal mode with the Threshold hum set low and steady. Lift the coil straight off the ground and allow the threshold to retune. Do not swing the coil in an arc off the ground. Moving the coil in an arc causes the machine to read the ground in an uneven manner and will complicate the ground balance procedure. Once the threshold has retuned, push the coil down to about one inch above the ground. One of three things will happen. The threshold noise will get louder; it will get quieter; it will stay the same. When the threshold sound stays the same, the detector is telling you that it is no longer being affected by the mineralization in the ground and you are ready to hunt. If the sound gets louder, you will need to turn the ground balance knob counterclockwise. If the sound gets quieter, turn the ground balance knob clockwise. Repeat the above steps until you find the spot where the detector no longer reacts to the ground and the threshold hum stays the same on the way down.
If you have a manually adjusted machine, it is very important to make sure that you are very comfortable setting the ground balance. You can practice this in your backyard or anywhere you can find a small area with no metal targets in the ground. Spinning the knob one way and setting the balance, then spinning it the other and resetting the balance is a good way to practice this skill. If you practice these just five minutes a day, you will get very good at ground balancing.
What is Super Tune?
Super Tuning is a technique to get better depth and sensitivity out of any machine that has an adjustable Threshold control.
The Threshold control is normally used to set the level of hum in the All Metal mode. A light steady hum is usually desired so that any small or deep target will cause a change in the audio sound. To Super Tune a detector, put it in the Discriminate mode and turn the Threshold knob all the way to the clockwise position. At this point, the All Metal mode will no longer operate correctly, but you will see an increase in depth and sensitivity while hunting in the Discriminate mode.
What is High Output Technology?
Most metal detectors work by sending out a signal, receiving it back, amplifying the return signal, and deciding whether or not to beep. One way of making the detector more sensitive is to increase the amplification of the return signal. This works well up to a point but can cause a machine to overload the circuits and become chirpy. Another way is to increase the initial signal going out, but once again, too much power and the signal will become unstable.
High Output Technology combines the increased transmitted signal and the high gain amplification of the return signal to get the best depth and sensitivity out of our lightweight, compact detectors.When a detector becomes chirpy, the most common reason is the noise to signal ratio. Signal refers to the information being passed through the circuitry and noise is any type of other interference. As the signal is amplified, the noise gets amplified as well. At Tesoro, we use high tolerance components and design them into the circuit to create a lower noise to signal ratio.
What is Target ID and how does it work?
Target ID is a feature that will give the metal detectorist more information about the target while it is still in the ground. It cannot tell you exactly what the target is due to the many variables present in an unknown target. A short list of these variables are as follows: the metal content of the target, the size and shape of the target, the target's orientation in the ground, the mineralization matrix of the ground itself, depth of the target, detector settings, and outside interference such as weather conditions, cell phone traffic, and electrical lines. All of these things can cause changes in the meter readings.
A basic detector works by transmitting a signal and receiving it back. This creates a field of electromagnetic flux lines around the coil. As metal passes through the field, it breaks or distorts the flux lines. A simple discrimination circuit measures the amount of distortion or shift and beeps or doesn't beep based on the settings of the machine. During the design phase of any metered-style machine, the engineer measures the amount of shift that the most common targets cause and programs a microprocessor to respond with a meter reading for those types of shifts. The testing can include simple air tests, field tests in a controlled environment, such as a test garden, or even complex reports from several different field testers. But at some point, someone decides that a type of target shift represents a specific meter reading. While this information can give a detectorist a basis to dig or reject a target, it is in no way perfect.
Is there a way that I can get more target information from a non-metered machine?
There is an easy way to find out more information about any target while it is still in the ground. When you get a target, shorten your sweep to about two to four inches over the target. As you move the coil over the target, slowly turn up the Discriminate knob. Check to see where the target goes away. Most detectors now have icons on the discriminate control representing the targets knocked out. This gives you the ability to make better decisions about digging any given target.
The best way to start practicing this method is to do several air tests and see how your detector responds. When you have a good feel for what your detector is telling you, try it in the field. For the first couple of months, check the target with your Discriminate and see if you can identify the target. Dig every target and verify how correct you are. After a while, you will become very good at identifying targets while they are still in the ground. You will dig less junk and be a more successful treasure hunter.
If you choose to use this method, always remember to turn your Discriminate knob back to the low setting before continuing to hunt.
What is Notch Filter Discriminate and how does it work?
Notch discriminate differs quite a bit from regular discrimination. When using standard discrimination, the higher the knob is turned up, the more items that are discriminated out. As discussed before, when pull tabs are totally discriminated out, so are gold jewelry, rings, and nickels. Notch filter discriminate is designed to knock out some pull tabs and to keep the good targets in. It is virtually impossible to knock out all pull tabs and keep all gold jewelry. The reason is due to the conductivity of the targets in this range.
A notch discriminate works by filtering or discriminating a band of target signals out without affecting targets higher or lower than the band. This can be done either with an analog or digital circuit.
When using a notch filter, check the setup by doing numerous air tests before taking it out to the field. It is to your advantage to make sure you are aware of how your detector reacts to both good and junk targets. If your Notch can be adjusted, tune it to knock out the most common types of pull tabs in your area while keeping in the targets you wish to find. The initial setup can be a bit time consuming, but once it is done, you will be able to find less junk targets and keep the good finds.
Can iron be rejected and gold nuggets still found?
Generally speaking, the best way to hunt for gold nuggets is to hunt in the All Metal mode. Nuggets, depending on their size, shape, purity, and orientation in the ground, will all create different signals. If you hunt in the Discriminate mode, some nuggets may be lost. The best way to get rid of iron is to search in the All Metal mode and then check the targets in the Discriminate mode. This allows you to search and find all of the possible gold nuggets. Checking the targets with the Discriminate mode turned up just high enough to knock out the small iron will give you much more information before you decide to dig. Practice this by doing air tests to see the best setting for your particular detector.
My detector still finds large iron targets, even with the Discriminate set high. Is this normal?
Most detectors can be fooled by some iron targets. There are two different ways that the machine can be fooled.
Circular iron can fool a detector because of its shape. Any iron, such as a ring or washer or even bent nails, are hard for the machine to identify accurately. As the iron starts under the coil, it gives the same type of signal as a coin. When the target is directly under the coil, it reads as iron, then reads as a coin as the coil sweeps over it. In most cases, the detector may give a signal, but it will be a broken or chirpy signal. With a little practice, the broken signals will start to stand out from good repeatable signals.
Large rusty iron can also give off signals no matter where the discrimination is set. When iron or any ferrous target is in the ground long enough, it starts to rust and break down. This causes a large halo of super mineralized dirt around the target. The halo is different enough from the surrounding ground matrix that the detector picks up a signal. The strength of the signal is so large that it momentarily overdrives the detector and it beeps. Signals of this nature usually seem bigger than the size of the coil.
The best thing to do when getting either a broken signal or a very large signal is to dig the target. Most of the time, it will probably be junk, but every now and then, you will be happily surprised by a very unique target.
Why do some pennies read differently than others?
The big difference is in the makeup of the actual penny itself. Older pennies, ones made before 1982, including the wheat back-style, are almost pure copper and will read up in the range of dimes and some other silver coins. The newer pennies are made mostly of zinc and tend to read in the screw cap range.
What is the best frequency for my type of hunting?
Contrary to popular belief, there is no one best frequency for any specific metal or metals. Any VLF-style detector that is operating between 3 and 30 kHz will do a fine job for any type of hunting that is done. This frequency range gives good depth, target separation, and is not overly affected by ground mineralization.
The ability to pick up good targets and separate trash from goodies is more due to the design of the detector, type of coils used, and several other engineering points that are brought up during the R&D phase. Comparing feature points of the detector model to the type of hunting you are planning to use it for will help you more than just comparing frequencies.
What is "crosstalk" and how can I avoid it?
Crosstalk is the interference that is caused by two detectors operating on the same frequency being in close proximity to each other. Depending on the gain and signal strength of the detectors, crosstalk can happen anywhere from 3 to 15 feet of the two detectors.
Crosstalk is most annoying when at a seeded treasure hunt. When you have a field with 50 to 100 or more hunters in it, you are bound to get at least one detector that is close enough to your frequency to cause crosstalk. Most manufacturers offer some sort of frequency shifter for coin hunt situations.
Frequency shifters change the transmitted and receive signals just slightly enough to keep another detector from interfering with yours.
How much does the moisture in the ground have to do with detection depth?
Moisture in the ground by itself has very little effect on the operation of a metal detector. Fresh water, such as rain or irrigation, is not much more conductive than the dirt it soaks into. Most metallic items in moist soil will start to corrode. As these items start to break down, they create a halo of super mineralized soil around the target. The halo effect makes the target appear bigger to the metal detector. Iron and other ferrous targets will corrode faster than other targets. Gold does not corrode, and silver, copper, and brass corrode more slowly than iron. So, while the halo effect will work on some targets, it will not work on all.
Saltwater is a little different than freshwater. Due to its nature, saltwater is more conductive than fresh. This may give a little extra punch down into the ground but will also cause most machines to chirp and chatter quite a bit more. It is especially bad at the surf line on a wet saltwater beach. You can effectively tune out most saltwater effects when the saltwater is consistent (when the coil is covered by a foot or so of water, for example). Along the surf line, the waves are still washing up on the shore and the sand is drying out. This causes pockets of sand that may be higher or lower in conductivity than the surrounding area and can play havoc on your detector. It is best to hunt in the Discrimination mode with the Discrimination knob turned up high enough to knock out iron and foil. This will cancel out a good portion of the saltwater effects. You may also have to turn down your sensitivity to stabilize the detector.
What are the best headphones to use?
Every detectorist has a slightly different style and likes a different type of headphone. For each style of hunter and hunting, there are several headphones.
The most obvious difference is the earpiece. A lot of detectorist like the full-cup style. These phones fit completely over your ear and block out most of the background noise. They work well for when you are trying to hear the faintest of signals. The downside is that if it blocks out the surroundings, you may not hear snakes or other predators around you.
On the other end of the scale are Walkman or ear bud-style headphones. They will concentrate the signal in your ear but will allow you to hear the surroundings around you as well. Ear buds are also much cooler to wear during the hot summer months.
Along with the types of cups are the ohm ratings and frequency ratings to consider. Headphones that are designed for listening to digital music have very high ohm and frequency ratings. They will allow you to hear greater nuances in the detector signals but are very expensive. Lower-priced headphones may not have the range of their higher-priced brothers, but considering that you are only listening for a beep, they work very well. If you are out in the field and accidentally break your phones, the inexpensive ones are much easier on the pocketbook.
There are a number of headphones that have active electronics inside them as well. Most of these types of phones have some form of compression/limiter circuit in them. They work by amplifying weak signals and limiting the strong ones. They will work well for chasing some of those elusive small, deep targets but may make shallow and deep target signals sound the same.
With all of the headphone choices out there, try as many as you can, think about the type of hunting that you do, and where you will be doing it. When you consider all of these factors, you will find the headphones that work best for you and your detecting style.
How much will using headphones increase the battery life?
Headphones take much less current to drive than the speaker in the detector. This fact by itself would tend to show that you will increase your battery life by using headphones. But you have to remember that even though the detector is not making any noises, the electronic circuits are still running. A detector that generates a square wave or has a display will be using more power than a detector that is using a sinusoidal wave and has no display. The increase in battery life will depend on your detector and hunting style.
Are rechargeable batteries better than alkaline?
There are two aspects of rechargeable batteries to consider. The first is cost. Rechargeable are quite a bit more expensive than regular batteries, but the cost is offset so that you will not have to buy them as often.
The second consideration for rechargeable batteries is the voltage. Most rechargeable have slightly lower voltage than their counterparts. Alkaline batteries have a voltage of 1.5 volts per AA cell. Most rechargeable batteries have a voltage of around 1.2 volts per AA cell. If your detector uses 8 AAs, you will have 12 volts with the alkaline and roughly 9.6 volts with the rechargeable. This should not affect your depth and sensitivity, it but will affect the time that you are able to hunt.
Are there any good places left to hunt?
Most places that come easily to mind have probably been hunted to death. If you thought of that site, chances are someone else has thought about it as well.
Doing research is the best way to find new places to hunt. Every city has some form of museum or historical society. This is a great place to start.
Joining a local treasure-hunting club can help as well. Check with your local dealer to see if there is a club near you. You may also want to contact a national club such as the "Federation of Metal Detector and Archaeological Clubs," "American Metal Detecting Association," or the "Gold Prospectors Association of America." A national organization will have several local groups that will allow you to contact hunters that share the same interests as you do.