The Minelab GPX 4000 detector was released in 2006 and was discontinued in 2009. The GPX 4000 was a pulse induction (PI) metal detector aimed primarily at the gold prospecting market but which has become popular also with relic hunters. The GPX 4000 was the first of a new series for Minelab, following up on the successful GP series models. Major changes involved a new digital front end for most controls, and a new Lithium Ion battery system, a vast improvement over the sealed lead acid batteries used on previous models.
"Simply the world's most advanced and powerful Gold Detector ever! The GPX-4000 follows on the success of its predecessor, the GP3500. Never before has Minelab offered such a versatile, easy to use gold prospecting detector, which has more power and punch than ever. The control panel layout has been re-designed to allow for a simpler. logical set-up procedure, incorporating an LCD Function Display. Simply scroll through the various functions of the detector and select the level required. All the variable level controls offer precise numeric settings for more accuracy. The lightweight Li-Ion battery offers the latest in battery technology, increased power, rapid charging time (4 hours), self contained charging system and robust housing. Source: Minelab 2006 catalog
Minelab GPX 4000 metal detector
- Advanced Digital Control System - Provides more operator control and functionality allowing the GPX-4000 to be fine-tuned for all types of searching. Pre-programmed search modes optimize the detector at a flick of a switch for different situations, whether general searching, patch finding or chaining an area. Access to a number of new variable functions allows the operator to select their own combination of settings to gain the best possible performance.
- LCD Function Display - The most obvious change to the GPX-4000 is the new LCD display on the rear of the control box. The user can simply scroll through the various functions and select the level required. All the variable level controls offer precise numeric settings for more accuracy. Gone is the inaccuracy of turning the control to "about 2-o’clock" - now you can compare the effect of different settings precisely and easily remember preferred levels, without the risk of settings being accidentally changed during transit or while detecting. All changes are saved automatically on shut down and reloaded when the detector is turned back on. The user can also restore the GPX-4000 back to factory pre-sets at any time.
- Gain - The Gain is now a numeric function that precisely sets the overall sensitivity level. In areas where search conditions are mild, Gain can be increased. In areas that are more difficult, it can be reduced. Using the Gain control in combination with other controls like Timings, Audio and Ground Balance enhances performance to a level never before possible.
- Sensitive / Smooth Timing - The GPX-4000 has two sensitivity options. The all-new Smooth option dramatically reduces signals from hot rocks and false ground noises, yet remains highly responsive to small targets. Depth on larger targets is sacrificed slightly, so in mild ground conditions the Sensitive timing found on previous GP detectors, now called Extra, is the preferred option as it will provide greater depth.
- Ground Balance Type - In addition to normal ground balance the GPX-4000 has an optional Specific ground balance, designed especially for use in very hot ground and that is especially useful with Mono-loop coils.
- Response – Serious gold hunters are familiar with the distinctive target signal from small nuggets; it tends to start in a rising tone and then drops to a lower one. Because there are usually more small nuggets than large ones, this target signal is quite familiar. The Response function allows the user to invert the normal target response so that when detecting deep ground for large nuggets, the target response is easier to hear and recognize.
- Motion - Different sweep speeds demand different software so that the detector can give the best results. The Motion function allows the operator to indicate their intended sweep speed to provide the best threshold stability and target response for that sweep speed.
- Volume Limit - Improvements have been made to allow potentially loud signals to be reduced without any loss of signal strength on weak, soft signals.
- Lithium-Ion Battery - Minelabs new lightweight Lithium Ion batteries hold their charge at almost full power for over 12 hours. The intelligent charging system is self-contained in the lightweight aluminium housing, offering rapid recharge times of 3 to 4 hours, from either the 12v auto or AC outlet adaptor (both included). The power available can be tested at any time through the LCD display.
- New Padded Comfort Belt - Included with the GPX-4000 is a new padded waist belt that makes wearing the battery harness more comfortable. A welcome improvement.