I now have about 50 hours on my excalibur so I am still very new to the machine but I believe that I have figured out how to get max depth in both Disc and PP. First, here are a few things I have found when testing out this machine:
1. A modded machine (ie different than stock headphones/coil) can produce drastically different results. So if you have a modded machine this does not apply to you.
2. Disc and PP are equal depth but each have different settings to get max depth
3. There are times when each has its advantages/disadvantages.
4. Threshold affects PP depth a lot and Sensitivity affects Disc depth a lot.
5. Your machine could be different due to slight variations that happened during factory tuning so please TEST yours before taking my word for it
To get max depth in Disc, use the following settings
Threshold: To where it just silent (cant hear it at all)
Sensitivity: 10 (9oclock) - max sens
To get max depth in PP, use the following settings:
Threshold: To where its nice and steady and can just hear it...sounds almost like a tiny steady buzz
Sensitivity: anywhere from 10 - 6 (9oclock to 12oclock). Anywhere below 6 starts to cause a depth decrease so if you can steady the machine try to keep it at least at the 6 position.
Now test a few coins/metals using these settings and see if the Disc and PP depths are nearly identical. I have found I get around 13'' inches at these settings with a quarter in both Disc and PP.