Hi Mikel
The Super Tune trick is used on the original Tesoro Eldorado and on some other Tesoro detectors. How it works on the old Eldorado, is first you perform a ground balance in the ALL METAL mode per the instructions in the manual, then you switch to the DISC mode and adjust the THRESHOLD knob clock wise, as you turn the threshold knob clock wise, deeper targets will become louder.
To give you an expample, the pencil eraser cap that I found today at 4" deep would sound like static, with the threshold knob set at the position it would be in after performing a ground balance in the all metal mode, then switching to the disc mode. Once you are in the disc mode, if you turn the threshold knob all the way clockwise, the eraser cap sounds like it is laying on top of the ground, and a coin at 4" deep will blow your headphones off. To get an idea of how deep your target is, you need to reduce the threshold by turning it counter clockwise, if when you decrease the threshold the target sound gets weaker, then you know the target is deep in the ground, but if you decrease the threshold knob and the sound stays the same, then the target is either on the surface or close to it.
The Super Tune will only work with my Eldorado in the discriminat mode, as far as I know it has no effect on discriminating targets, that is still effected by the DISC knob. Hope this helps.
colt