4MHz is a Big Improvement over 5MHz!
Installed the update and took my 800 to a local park that I hunt often for deep silver. I started with the stock coil, running in Park 1 in single frequency 4MHz. I was immediately surprised how different the machine was working. There were deep targets everywhere, and many were high tones. I was immediately suspect. All-metal mode revealed many of these targets were iron. I dug several of the targets and they were disappointing--clad and aluminum that gave a much higher Target ID. I started to use my Custom Profile in Multi-frequency to cross-check the Target ID. [This requires only 1 button press on the 800; I turn the User Profile on/off to switch between 4MHz and Multi.]
I did not find any silver today, but I did find several deep dimes from the 1960's and '70s. In 4MHz the Target IDs were 34-38, but switching over to Multi and the Target ID became faint and fell to 26-28. I felt that if I was searching in Multi I could have easily have missed those targets.
I dug several targets that gave Target ID of 26-32 in 4MHz, but were 16-19 in Multi. Yup, round aluminum pull rings. I dug a target that gave a solid 21-22 in 4MHz, but was a 3 in Multi--it was a 3"-deep crumpled gum wrapper.
I dug no iron because the signals were easy to distinguish. I usually dig several bolts, nails, and bazinga but not today. I didn't realize that until I wrote this. I was not cherry-picking either. I set out to dig as many decent targets as possible to find out how it responds to different targets.
For the sake of brevity, here is my impression of the software update. Yes, 4MHz is MUCH more stable than 5MHz--that change alone is worth the update. In 4MHz the VDI is more stable, the numbers don't bounce like they do in 5MHz, and EMI is imperceptible. (Admittedly there is little EMI where I was but 5MHz was still not stable.) Deeper targets have a sharper tone compared to 5MHz and Multi. I did not notice any change to stability in Multi-frequency compared to pre-update.
Conclusion: The 4MHz will go deeper and is more stable than 5MHz and 10MHz. I say this because I compared readings in each of these frequencies, and yes the machine was noise-cancelled and ground-balanced in each frequency. The audio signal is just as consistent as the Target ID, making good targets more obvious--this should aid new users.
There are a few drawbacks:
1. The Target ID is very inaccurate in 4MHz. You can remedy this by cross-checking in Multi before digging deep targets. Requires only 1-button press on the 800 if you turn Custom Profile on/off.
2. 4MHz is not used in Multi mode. Hopefully Minelab changes this in the next update by substituting 4MHz for 5MHz--once they figure out how to improve target ID in 4MHz.
Happy Hunting!
