The sensitivity control in auto tune is turned to almost it's highest setting to ensure you hear the threshold sound. The threshold sound on a CZ is warbly and not as smooth as threshold based machines ( remember the CZ is a silent search machine in discriminate mode while other machines out there have a threshold tone when hunting in discriminate mode) and the sensitivity control acts like a threshold adjustment in auto tune mode.
When ground balancing, keep the sensitivity close to 9 or 10 throughout the procedure. Do not lower it. You have to HEAR/LISTEN to the threshold changes THROUGHOUT the process of ground balancing. The only knob you should be adjusting is the ground balance knob. Your volume at 7 is good, as long as you can hear the threshold, as well as the GB at 10. Start bobbing/moving the coil up and down at a moderate pace, starting from about 1-2 inches from the ground to about 8-10 inches. Listen to the threshold sound. It will either RISE ( go high in pitch) when the coil is lowered to the ground, or RISE when the coil is raised from the ground. What you need to do is starting turning the ground balance knob as you continue to bob the coil, until there is NO RISE in threshold when going up and down. The threshold sound should be stable and sound the same ( or pretty close to the same) when bobbing. Once you get that, you are done.
When you then switch to discriminate mode is when you then lower the sensitivity because it is probably too high at that point. Lowering the sensitivity will limit falsing in discriminate mode and you will still go deep. If you can run higher than 5 or 6, try it, but after a certain point the CZ will not go much deeper but have a wider footprint and be more subject to iron falsing and you MUST SWEEP SLOWER with sensitivity greater than 6 ( at least this is what I have found on my CZ's).
When hunting in auto tune, the sensitivity control should be close to 9 or 10...high enough to be able to continue to hear the threshold and be able to distinguish the changes in the threshold sound. If the sensitivity is too low, you will not hear the threshold sound at all. You would still hear the high pitch 'wee' when going over a bigger or shallower target, but since you are not hearing the threshold at all, you will not hear the deeper or smaller targets that would only give a slight change in threshold sound since you are not hearing the threshold at all.
Last thing...there are times, especially beach hunting in salt mode, where there is no change in threshold at GB setting 1 or 10 so I just leave in in the middle at 5. Not sure what other CZ users do or what they set their GB to when they can't ground balance. Also, remember to check your ground balance every so often. The ground can change, even from one small area to another, and it's very important to have a good ground balance to eliminate falsing and get the best depth from the CZ.
Hope this helps and did not confuse you ! I read it twice but I know what I am trying to say so it makes sense to me....it may not make sense to you so please let me know !
