7.5khz 9" Default Coil versus 18.75khz 6" DD

[jimgolian]

I have the default 7.5khz 9" coil and the 18.75khz 6" DD. The 9" one seems to go deeper than the 6" one. From what I read online I thought the 6" would go deeper for some reason. I read the manual and the 6" is supposed to be better for shallower targets.

My question is this:

Which coil is better for prospecting for gold in the hills of California?

 

[khouse]

The stock coil goes deeper. The 6 inch hfdd coil is the one you would use for prospecting.