Minelab GPX 4000-5000 Manuals & Timings Charts

The secret to the Minelab GPX series is thoroughly understanding the timings and when to use each one. Timings are variations of the basic pulse induction technology at work in the GPX series that gives you far more flexibility than exists in other pulse induction detectors. Unfortunately this extra flexibility also adds complexity, and so it is not unusual that some people may not be using the optimum settings in many cases. It is very important when investing in a Minelab GPX detector to take the time to read the manuals and study until you fully understand what the settings do and how to adjust the detector for the best performance. Otherwise you will not be getting all the potential out of your investment.

The chart below shows the timings and what GPX models they are available on along with a general description. The descriptions are from the owners manuals that are available by download at the bottom of the page. In general you should always use timings as near the top of the chart as possible, with the exception of the Salt settings. Those are for alkali flat and salt water beach areas only. Using timings designed for more mineralization than is actually required may result in less depth on desired targets. Imagine the timings as another sort of ground balance setting. Low mineral settings are more powerful than high mineral settings and should be used whenever possible.

Some confusion is the result of the timing names. Some people assume the Fine Gold timing is best for fine gold. This does make a sort of sense, but the fact is Fine Gold is just better than other high mineralization timings on smaller gold. In milder ground Sensitive Extra will obtain better results on small shallow gold. It is also very important to know that some timings work better with one coil type or the other.

**Minelab GPX Timings Chart**
Little or No Mineralization		Coin/Relic (GPX 4800, 5000 ONLY) Coin/Relic is for use in lightly mineralized soils including many beaches and loamy soils. It offers maximum detection depth on a range of target sizes, significantly greater than any other timings. However, if the ground is any more than lightly mineralized, the detector may not ground balance properly. On ocean beaches containing significant quantities of black sand, better results may be had by using Normal or Salt settings.
Mild Mineralization		Sharp (GPX 4500, 4800, 5000) Sharp is similar to Normal but creates a more powerful detection field. It is capable of an improvement in depth, but is more susceptible to interference and will increase the severity of false signals in difficult grounds. This timing is best used in quiet conditions and can work well in combination with Deep Search Mode with a reduced Rx Gain setting. Sharp is an excellent tool for pinpointing faint signals due to the very "sharp" signal response. Sharp will work best with DD coils in most gold field locations.
Medium Low Mineralization		Sensitive Extra (GPX 4000, 4500, 4800, 5000) This timing may increase the signal from certain hot rocks near the surface, but can actually help smooth out the Threshold in certain ground types, particularly with Double-D coils. In mild ground conditions Sensitive Extra will provide the best signal response on a small, deep target.
Medium Mineralization		Normal (GPX 4000, 4500, 4800, 5000) Normal gives you the best performance on a wide range of soil conditions, and it will provide the best depth on a wide variety of target sizes. It works particularly well with the supplied 11" DD search coil for general detecting. You should always use Normal in new areas where you are unsure of the soil mineralization and the depth of targets.
Medium High Mineralization		Salt Coarse (GPX 4000, 4500, 4800) The effect of alkaline salt mineralization is vastly different to the effect of ironstone and mineralized clays. Normal should be tried first in these areas, but if the Threshold is too unstable then better performance will be obtained in Salt-Coarse. Using the Salt-Coarse timing may result in a loss in signal response to smaller targets. However, the response on larger items remains relatively unaffected and ground noise is usually minimized.
Medium High Mineralization		Salt/Gold (GPX 5000 ONLY) Provides the best signal response on small to large gold in salt saturated and mineralized ground conditions. It should work well on dry inland salt lakes, high salt concentrated goldfields, and mineralized saltwater beaches. Extremely salt saturated soils may still need to be searched with the coil switch in Cancel (using a Double D coil).
High Mineralization		Fine Gold (GPX 5000 ONLY) Fine Gold is sensitive to smaller targets in highly mineralized ground. It provides a sharper signal on small gold compared to Enhance, and improves the detectability of rough/flaky gold and specimens, while ignoring most hot rock signals and false ground noises. Shallow, highly mineralized ground where gold has been found previously should be re-examined with Fine Gold, and best results will be had by using the optional 8” and 11” Commander Monoloop coils. Note: Sensitive Extra will provide superior results on small gold in milder ground.
Very High Mineralization		Enhance (GPX 4500, 4800, Improved in GPX 5000) Runs quietly in most heavily mineralized, variable and "hot rock" infested grounds using a monoloop coil. It is more sensitive and detects deeper than Sensitive Smooth but can be slightly more affected by severe ground mineralization.
Severe Mineralization		Sensitive Smooth (GPX 4000, 4500, 5000) Sensitive Smooth is optimized for an improved response on smaller, shallow nuggets in severe soils. There is a loss of depth on bigger targets; so you should not use this setting when seeking out large, deep nuggets. Sensitive Smooth is best suited for use with monoloop coils in difficult soils. It eliminates most false signals from hot rocks, and ground mineralization, whilst retaining excellent sensitivity to small targets.

The example below shows three common timings and where they should be used. It also highlights why using the wrong timing for the conditions can result in missed targets.

**Minelab Mineralization and Timing Example**

The following chart illustrates the procedure for finding the correct timing for each situation. In general, always start with the Normal timing. If the detector is stable and quiet, try timings on the left - Sensitive Extra, Sharp, or in rare cases, Coin/Relic. If ground noise or hot rocks present problems in Normal, then try timings on the right - Fine Gold, Enhance, or Sensitive Smooth. Salt settings should generally only be used on alkali ground (salt flats) or salt water beaches, but may have applications in other ground. The goal is always to find the most powerful setting that allows for stable operation. Each timing can be adjusted within certain parameters, primarily through the use of the Gain and Stabilizer settings. Adjusting for a lower Gain, for example, may be preferable to going to a less powerful timing.

Finally, each timing may work best with a certain type of coil (DD or Mono) and the timings have varying level of resistance to Electro Magnetic Interference (EMI). The matrix below attempts to show which timings offers which benefits and strengths/weaknesses.

The simple chart below can be printed out and taped or glued on your detector shaft as a reminder in the field as to which timing may be best. Click on the image to download a large version.

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Minelab GPX 4000-5000 Manuals & Timings Charts

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