Minelab is not double speaking... you just have to know what they mean by what happens when you turn up the threshold too high. I thought this might be confusing but I was too lazy before to take a screenshot of the manual. A picture is worth a thousand words... so check this out... and then I'll explain a bit further.
Notice how the size of the two targets in both graphs are the same extending from the threshold level? That is because the threshold level sets the lowest audio volume level that the detector produces. The highest volume is adjusted by the Volume Max Limit setting. All sounds in between are compressed to fit the scale, i.e. there is no clipping of sounds.
If you set the threshold below your audible hearing level, you cannot hear the threshold hum and won't be able to hear some of the really soft sounds. This is really only true when you don't have your gain maxed out, and faint signals come through as faint sounds.
But if you adjust the threshold too high, i.e. north to 40! which is what Minelab says... then basically you are going to hear a threshold hum just about as loud as your detector can make sounds... and all of the signal sounds will be compressed within the range between that really loud threshold level and the volume Max Limit level. Basically, you'll just hear BUZZZZZZZZZZZZZZZZZZZZZZZ!!!!!! constantly... lol
So if you set your threshold to just above your audible hearing level for the headphones you have and the environment you are in... you will get the maximum dynamic range of audio volume possible for the range of target sounds produced by your detector.
Ant said:
I hunted with my threshold at the lowest point of audible hearing and I was missing small deep targets. When I went back to the factor setting of 16 I got better results.
When you say you had adjusted it at the lowest point of audible hearing... could you barely hear the threshold then? Because you want it just above your audible hearing level so that you can clearing distinguish when it nulls out and when those faint signals bump it up a touch.
When you went back to the factory setting of 16, what do the deep faint signals sound like to you now vs. when the threshold was lower?
Also, what Gain setting are you running?