We have been reading about the development of the simple nugget detector by Whites, the GMZ. The big question is, why did they build a nugget detector with a silent threshold?? Generally a nugget detectorist with a vlf detector runs his manual ground balance either dead on or slightly positive for a bit more push on the signal, and sets his manual threshold so you get a slight buzzing from the circuits so you can hear any slight difference in sound as you are detecting for gold. Any ideas as to why this machine was built with a silent threshold?? Is it a auto threshold of some sort, auto adjusting to conditions? Will it break silent threshold on a half grain nugget? What are the advantages of this silent threshold?