Tones with VDI

[Theppgcowboy]

I found a 1903 liberty nickel the other day. I am thinking that it gave me a 61 VDI number but the tone was noticeably higher or richer I think, again I am just thinking. I have not really been paying attention as to what tones corolate to what VDI, but will different metals with same VDI give different tones? I really need to set me up with a test garden.
Currently using the sifter and hot programs.
I guess I just need to dig everything. I am starting to know a crown cap but pull tabs fool me every time. I guess I really need to pay attention to tones and low 60 VDI.

 

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[vferrari]

To correlate tone to VDI, need to know three things - (1) whether you are in full tones or multi-tones (where you can set each of up to 5 tone breaks manually), (2) your operating frequency as VDI and full tones increase with frequency for the same target unless...(3) you have selected ID NORM to ON (which is the default) in which VDI and full tones tone are normalized to 18 khz operating frequency regardless of actual frequency (ID NORM does not apply to HF coils where VDI and full tones increase with frequency).

Crown caps are pretty easy to tell audibly even if they give a "dig me" VDI - they do not have the tonal intensity of coins, sound scratchy or distorted if rusty (especially when the center of the coil passes the edge of the target), and they can be made to sound even worse or broken up using higher silencer settings (expert setting under reactivity).

Pull tabs are going to fool you 95% of the time so just get used to it. They can easily sound like nickels or, more importantly, like gold rings unless they are severely bent or broken in which case their target sound will have the right tone but sound distorted or broken.

 

[Icewing]

Set a silver dollar a couple inches from a horseshoe (not touching) and give it a test swing, then you can throw away your cheat sheet.

 

[vferrari]

I personally don't use a cheat sheet but dig mostly on tones but, yeah, big iron will drag down the vdi of a high conductor. That is where multi-tones or a "two-tone" pitch program (using iron volume) in combo with the some disc and notch can help with unmasking as discussed in some of the other threads.