HOW DO I KNOW WHAT SOIL/TIMING I SHOULD BE USING?

You can never predict what level of soil mineralisation will be present in any given location, which is why Normal is the recommended Timing to start with. Then, you can let the detector tell you which Timing to use by sweeping the coil and listening to the stability of the threshold.

After performing an Auto Tune and Ground Balance you should commence searching, and if the detector is too noisy or signals on lots of hot rocks, then the Timing you are using is too aggressive for the ground you are on. You need to select to another Timing closer to the dark end of the below scale, e.g. Enhance

WHAT IS THE BEST WAY TO REDUCE THE EFFECTS OF EMI?

The GPX 5000 is known to suffer from Electromagnetic Interference (EMI) particularly during stormy weather. There are three known reasons for this interference:

The sensitivity of Enhance, Fine-Gold and Sharp timings will detect extremely small nuggets, but unfortunately any EMI as well.

Because of the superior ground handling ability of the GPX 5000, the use of big Monoloop coils is quite common. A coil's field punches just as high above the ground as it does into the ground, so you can see that a bigger deeper coil will be more prone to EMI.

The general smoothness of the detector means that any warbles or chatter due to EMI are a lot more obvious, and can be mistaken for a target signal.

On bad EMI days here are a few tips that can keep your threshold purring:

Use a Double-D coil, and keep the coil size to a minimum for the ground being worked.

Avoid using the Fine-Gold and Sharp Timings. Normal and Sensitive Extra will often provide a smoother threshold.

Use the Very Slow or Slow Motion speeds.

Use the Quiet or Normal Audio Type.

To allow the detector to accurately pick the quietest operating channel, select the Fast Motion speed, do an Auto tune, and then go back to Very Slow Motion.

Set your Rx Gain first and then use the Stabilizer to fine tune.

Whilst searching, you may find that the threshold starts to wobble. A quick tweak of the Manual Tune by a few numbers will return the threshold to a smooth hum.

A combination of the above should make a big difference in the stability of the detector and will allow you to continue to find gold in difficult conditions.

EVERYONE TELLS ME A MONOLOOP COIL IS DEEPER & MORE SENSITIVE COMPARED TO A DOUBLE-D COIL – SO WHAT ARE THE ADVANTAGES OF A DOUBLE-D COIL?

Wide ground coverage at depth per sweep, less overlap required

Less prone to Electromagnetic Interference (EMI)

Can use the Iron Reject function

Improved ability in really wet soils

Allows the use of the Cancel mode, to operate near power lines

Pin-point along the centre of the coil

Large deep targets have a more defined (narrower) response

Reduced false signalling in highly mineralised soils

Less susceptible to signal on buried charcoal

Works well with Tracking Ground Balance. 

GPX 5000 & GPX 4800: UNIT GIVES VERY LITTLE DEPTH AND SOMETIMES ONLY DETECTS VERY LARGE TARGETS, WHY?

Ensure you are not using a Monoloop coil with the Coil Rx switch set to Cancel.

GPX 5000 & GPX 4800: HOW CAN I TELL WHAT TYPE OF COMMANDER COIL I HAVE IF THE LABEL IS NO LONGER PRESENT?

Monoloop coils have a perfectly round cable.

Double-D coils have a flatter cable due to the two internal cores.

Put the Coil/Rx switch in Cancel. If you have slightly reduced depth than you’d expect, then your coil is a Double-D. If you have virtually no depth, then you have a Monoloop coil.

WHAT IS THE PURPOSE OF THE STABILIZER CONTROL?

The Stabilizer function controls the point at which faint variations in the Threshold begin to be heard. These faint variations can either be ambient noise or faint target signals. As you increase the Stabilizer control, faint target signals will become louder, but the noise level will also increase, which may potentially hide a desirable target signal. The Stabilizer allows you to mask these faint variations to provide a perfectly stable threshold, improving your ability to identify faint target signals.

The Stabilizer is best left in the FP (factory preset) position until the soil conditions in the location are determined. Once the Rx Gain level has been set for the local conditions and other audio settings have been selected, the Stabilizer can then be used to fine tune the Threshold stability.

To find the optimal position of the Stabilizer, ensure that the coil is being swept across the ground. One number below the point at which the threshold begins to chatter, is generally the best setting.

The effect of the Stabilizer could be seen as having a similar effect to that of the Rx Gain control. However, the Stabilizer affects the audio processing only and does not change the Receive (Rx) signal, so should be used as a final stage fine tune. After making any adjustments to the Stabilizer, if the ground conditions change or you wish to change coils, you may need to reset the Rx Gain, but before doing so, return the Stabilizer to the Factory Preset setting first. This will ensure you select the most appropriate Rx Gain level to suit the conditions, and then you can fine tune using the Stabilizer.

Tip: By turning the Stabilizer control close to minimum (anti-clockwise) the threshold will be very stable, but you will have lost a lot of sensitivity to smaller targets. This can be a desirable feature in certain scenarios such as looking for large nuggets in a high-trash area, or using the GPX 5000and GPX 4800 to search for coins or treasure.

Tip: We would recommend the best order for setting these controls are:

Select an appropriate Search Mode

Select the desired Audio Type

Adjust Rx Gain until the threshold starts to break up

Adjust Stabilizer to smooth out the threshold.

HOW IS TARGET VOLUME DIFFERENT TO NORMAL VOLUME?  

The Target Volume controls the strength of target signals, and at settings above 8 it will slightly increase the volume of the threshold as well. This is useful for very windy conditions, for people suffering from hearing loss, or when using external speakers. With the audio amplifier built into the Li-Ion battery pack, you can plug a speaker directly into the battery, and set an appropriate level of amplification using the Target Volume. Be aware that when switching from headphones to an external speaker, you may need to make minor adjustments to your Threshold and Volume Limit controls.

The Target Volume can be used as an Audio boost in quiet conditions, and can also be used to reduce or smooth out ground noise signals in highly mineralised soils. This is a powerful feature, and will work in conjunction with the Stabilizer control, giving you the ultimate in fine tuning ability. A bit of experimenting may be required to find the optimum combination in different conditions.

NOTE: Whenever adjustments to the Gain are required, due to a change of coil or location, make sure the Target Volume is returned to the FP setting first. You can then fine tune to suit the new conditions.