There is a popular misconception that when finding the best metal detector for the money it should be a multi-purpose unit – one which can be used for gold prospecting, treasure hunting and also possibly as an underwater machine. In reality there is no single detector that is first class for all these things. There are different detector circuits designed for various specialised jobs. There are basically several categories of detectors:
1. Gold prospecting detectors 3. Treasure hunting detectors
2. Dual purpose detectors 4. Underwater detectors
These are by far the most popular types of detectors sold in Australia.
There are three basic types currently available:
Multi Point Sensing
This technology has only been released since mid 1995 and is currently known as the Minelab SD2100 v2 and SD2200 v2. Minelab has the exclusive patent, which was invented by Australian electronics genius, Bruce Candy. They are very efficient all-round prospecting detectors. They detect at far greater depths than all VLF detectors in the typically mineralised soils of this country. This is because they ignore soil mineralisation to a far greater degree than VLF types of detectors. Soil mineralisation continues to be a barrier to obtaining detector depth penetration for other types of detectors. The SD detectors also operate more quietly. With other machines, ground noises are created by soil mineralisation, which can sound like a gold signal. The SD series mostly eliminate those noises and also doesn’t signal “hot rocks” nearly as much as other machines. “Hot rocks” are rocks containing minerals which can trigger off a signal.
- · Best points – Greatly superior depth over VLF machines. Quietness of operation. Speed of ground coverage.
- · Worst points – More expensive when compared to VLF detectors.
- · Who buys them? – Professionals, serious amateurs and some hobby detectorists.
Dual Voltage Technology
Minelab GP Extreme and GP3000 incorporate DVT which has all the advantages of Multi point Sensing and is based on it, however it incorporates the latest technology which has the added advantage of even greater sensitivity.
VLF Prospecting Detectors
Very Low-Frequency detectors have been around for over 30 years, and up until 1995 were the best metal detector machines to use. However since 1995 when the Minelab SD series came out with incredible detecting depth increases, they have fallen in popularity. It is an advantage for an all-round multi-purpose VLF detector to have more than one frequency choice. A low frequency enables nuggets of larger than bean size to be found at greater depth. A high frequency enables smaller nuggets to be located. That’s why it is a distinct advantage to have more than one frequency available at the flick of a switch. The VLF detector which has the best range of frequencies at present is the Minelab Eureka Gold with its, 60, 20 and 6.4 Khz choice. A further feature of the Eureka s its auto ground tracking (AGT) ability. It tunes itself to suit the varying ground conditions as the detector operator moves about. The earlier version was the Minelab XT 18000
Some Vlf Detectors with very Hight frequencies (50KHz – 70KHz range) are capable of locating tiny nuggets at shallow depth, especially if the soils are only lightly mineralised. However because of their high frequency, they have trouble locating larger nuggets at depth where the soil is highly mineralised. It is worth considering that many nuggets on some goldfields are of a smaller size. This is particularly true of ground that has been previously detected. Detectors operating in the high Khz range (Fisher Gold Bug 2, Whites Goldmaster) are far better suited to detect nuggets up to pea size than other VLF machines. With a small coil fitted, they can detect in crevices and cracks in creek and gully bottoms, where little nuggets are frequently lodged. Also, being lightweight detectors with narrow elliptical coils, they can be manoeuvred in and around tight areas.
Because of their high sensitivity the manual tune machines will need frequent ground balance tuning, and this can take a little time for beginners to master, and always slows detecting down. If tuned perfectly these detectors can be very sensitive on tiny nuggets, however, SD machines with the small mono coils will generally outperform them even on tiny nuggets.
- · Best points – Lower price range. Available in auto ground tracking. Very light and portable.
- · Worst points – Can be frustrating detecting an area that has been properly detected with a SD series detector or where the gold is deep down. Need tuning very frequently if without auto ground balance. They beep on Hot rocks.
- · Who buys them? – Some amateur hobbyists.
2. Dual Purpose VLF Detectors
Some manufacturers have attempted to make a detector, which is good at both treasure detecting and gold prospecting. So while there are detectors, which will do both jobs, none of them are actually competitive on the goldfields. Ideally, a machine that excelled as a dual-purpose would detect deeply in the high mineralization of the gold fields and yet have a good discriminator to cancel out unwanted metal objects. In reality though, none of the good goldfield detectors have a good discriminator, which will work at depth. The best treasure hunting detectors which discriminate well, are only somewhat poor performers on the goldfields. One day someone will make a detector that is the very best on the goldfields and yet has a full depth discriminator. The challenge is to make a discriminator that works well in high mineralization areas typical of goldfields. Currently, discriminators lose efficiency in these conditions. The “hotter” the ground gets, the more unreliable they become. Some detectors that can be used on the goldfields (at the VLF level) though are rather poor performers, but have good discriminators in normal conditions are – Minelab Sovereign GT (review), Tesoro Lobo and the Garrett Infinium LS Metal Detector.
- Best points – Versatile, generally inexpensive, good discriminators.
- Worst points – Cannot compete on the goldfields with the top prospecting units.
- Who buys them? – Hobbyists and some serious amateurs who dabble in coin and nugget hunting.
3. Treasure Hunting Detectors
If you are looking for old coins, jewellery and artifacts, you’ll probably poke around beaches, parks and old ruins. Your first priority is a good discriminator. Generally, with this type of machine, the further you turn the discriminator knob the more metals will be rejected. This means you won’t be digging too many rubbish targets. There is quite a variety of models to choose from in every brand. Some are very sophisticated and complex. Others are extremely simple to use. It’s a matter of your own personal tastes and the size of your wallet.
- · Best points – Very good discriminators – reject rubbish and enable you to cover ground quickly
- · Worst points – On the goldfields, none of them excel and some cannot be used at all.
These are generally waterproof to around 150 feet deep or more. There are three main types:
Pulse Induction (PI)
Types like the Fisher P.I. and White’s Surf PI Dual Field can have excellent quality, ability and depth in salt water, but have little or no discrimination ability. They are not much good on the goldfields.
Such as the Fisher 1280-X may discriminate well but don’t have very good depth in salt- water conditions. They are useable on the goldfields with limited success.
Broad Band Spectrum Detectors (BBS)
- · Best points – They are waterproof!
- · Worst points – Not very user-friendly on land. Some won’t work well in the goldfields.
Choosing a suitable detector can be easy or difficult depending on what your needs are. For example, if you’re serious about gold prospecting and determined to learn and can afford it, there’s nothing to compete with Minelab’s GPX 5000 or GPX 4800. If you can only put in an occasional weekend prospecting, and don’t wish to spend the extra money, the choice is not quite so easy. Most would buy the auto-ground balance Garrett AT Gold, White’s GMT, or the Fisher Gold Bug Pro detector if they like to buy a new unit, however a second-hand Minelab Eureka Gold Metal Detector would be the best performers under $1000.
If you are going to go underwater, the range is limited to specialty machines. If you want to spend a lot of time treasure hunting, then go for discrimination properties and ease of use of a detector like the Minelab Excalibur. If you are unsure about what type of detecting you may settle into, that makes deciding a lot harder for you then a all purpose, all terrain metal detector, such as the waterproof Garret AT PRO. If you prefer a specialized prospecting detector like the Minelab GPX 5000 Metal Detector, even though it has none or little discrimination ability, be prepared to dig more rubbish on the beaches and parks. Detectors are getting better all the time and the best metal detector for you is not always easy to find but with good research, reading reviews and deciding what you are looking for find the best for you in no time . There are plenty of nuggets out there for the diligent searcher and lost coins and jewellery supplies are continually being replenished.