We are starting to run some new boards out that have a far greater performance on tiny gold and big deep gold using large coils. The new boards have a set of very fast low noise intermediate drivers added, inclusive of new components to give a different attack and decay phase shift that helps greatly with the ignoring of hot rocks.
This allows far more gain to be used while at the same time reducing the response to hot rocks and ground noises. The new settings allow the use of a large mono coil even in normal timings as to be adjustable to the point where it is far less sensitive to ground fluctuations and the dreaded hot rocks.
Now just because we put a turbo charger on the V8 it does not mean that you can wind everything full and go hoon around in the rain, you just end up doing wheel spins and getting nowhere fast.
The type of ground is the main thing that you have to deal with, red hot iron stone ground means to reduce the gain so that the input circuit of the detector is not overloaded by a huge ground signal, reducing the gain and the variable frequency control helps control the noise,
In mild ground such as pipe clay and some river banks it is possible to run the gain nearly full on, this has not been possible before as the earth field creates too much of a weee wooo sound when moving the coil up and down a river bank.
As the biggest deepest gold is more likely to be found in normal timings the upgraded sub board allows the use of normal timings in most circumstances, even with a 24 inch coil. Tiny gold such as spurry reef or 0.005 gram bits are easily detected in Enhance mode with a small coil, running the variable frequency around 200 or more with the gain set as to allow perfect ground balance is outstanding. My own testing with a mono 10 x 5 coil on a 0.005 gram gold can actually cause an overload signal on the detector. This tiny gold was detected out to 8 cm.
The real testing should always be carried out on the ground that you intend to detect, bury a target such as a gold nugget or melted aluminium and try to get it so deep that you can just detect it, experiment with settings and coil sizes as to get the best depth without making the detector unstable and noisey.
After playing with the detector and if you get confused with the changes, its very simple to reset the detector by turning the detector off, holding the power switch down until it goes dee dee dah and turning the control to reset all, then turn the other control to do the reset. It is as basic as it sounds.