All metal/motion Vs disc mode

Guys this may seem to be an inane question to you technical gurus but what is the difference running the F75LTD in Disc mode....zero disc....mono sound (1) say 50-70 sensitivity, Boost Process and running in all metal/motion say 50-70 sensitivity? In bad ground why is there still a loss in depth (compared to all metal/motion) with discrimination mode, when zero discrimination is selected?

Ross

In a nutshell: Filters & audio boost. In the wide-open ID mode..... very weak audio signals are boosted to fairly loud levels (quite beneficial)...... and in the all-metal mode..... weak/deep targets are more difficult to hear due to modulated audio.

If I remember right, the F75 still has a certain degree of iron rejection even with the disc set to 0 or very low numbers. That was one area that the F75 and T2 differed majorily. I recall one site I hunt regularly that has artillery shells and frags in it and the F75 could only get them in all metal where as the T2 could get them in disc mode if you lowered it enough....the F75 would knock out a artillery shell chunk the size of my fist at its lowest disc setting. Thus another reason for improvement in all metal vs disc. ANY degree of discrimination is bad when things are reading as iron at deeper depths.

Let me ask a question concerning using all -metal mode as a deep coinseeker in a sholl plyground that has been picked to death. This school has been around since before the Civil War and Gen Grant even commandeered the school as a hospital after Shiloh's battle. My goal is to target the deep objects while disregarding the top 3 to 4 inch that has been picked to death. What do I listen for as I swing across, say, a barber dime at 11 inches deep while ignoring the cab slaw and pop tops that other detectorist saw fit to leave in the field???? An iron grunt and very low volumn??? Is the audio in all-metal mode modulated????? Will it sound quieter on deeper stuff???? That should be beneficial shouldn't it??? Only dig weak, barely audible signals????
I know that there are coins deep in this playground that hasn't been reached yet. My goal is to get them,

Daniel, my f-75 will sound off a high tone on a large hunk of iron and will pick up very small pieces (low tone) with zero disc.

Kevin, I hunt an area very similar to what you describe, it's a tough place to hunt because of all the years of trash bits. All-metal on the f-75 is impossible to use there. I have had sucess using the f-75 and the stock coil and the 5" with zero disc, 4 tone and a very slow swing speed. The amount of targets in the ground and the speed your brain can process the many signals, will determine your swing speed. I have to concentrate and be totally focused on what the detector is telling me....the rest of the world, thoughts etc are tuned completly out. The coins I massage out of there are mostly indian head pennies with an ocassional seated dime and half dimes. There are many more there but masking is the enemy. It is certainly a challange. Tom D. has posted many good tips and tricks for this scenario, you can find them with a search.

Ozzie -- That's at 0 disc correct? What happens on yours if you bump it to a setting of 1 or so? I know on the T2 that it wouldn't reject a cannonball frags until a setting of 19-20 pending on the size, vs the F75 where it began rejecting them at around 1 or 2. I remember when artillery frags hunting I had to always drop to all metal on the F75 whereas with the T2 I had a wider range in which I could still operate in disc mode and not miss the shell pieces or grape shot.

The level of mineralization will dictate if a 11" deep coin will report as a

1) weak audio 'iron' target
2) weak audio 'coin' target
3) weak audio 'non-ferrous full-spectrum VDI' target
4) non-detection

The heavier the mineralization .... the less desirable the (performance reporting) results.

When picking thru trash using an Exp i turn the gain up to 10 as high as it will go, because like Tom had mentioned it changes the modulation making everything even the weak signal audiable to the point they dont get lost as mineral sounds. The lower the gain the more you miss in those areas. AM is noisy but it does come back quicker from a null so i have to move slow, which the Exps do well. I would hunt the area using several different methods also.... maybe a sensitivity adjustment. To much sensitivity and you are getting to much of the deep iron, a little less maybe you can get between the trash and big iron. Paterns work as well in some cases.

Daniel, zero disc.
I can not hear a difference between 0 disc and 1 disc. I also don't use disc on the 75 unless I need to calm down emi and it starts calming at 5 or 6.
I don't like how the disc works on the 75. I'd rather hear the full/all tones verses all the crackels and pops. That's my only complaint about the 75.
The explorer/e-tracs discrim is a good example how disc should work, imho.