Iron bias
Here is one test.
Clad dime and old square nail (seems doesn't have a head).
Park 2 factory disc. Speed 6 iron bias 0.
Down the nail barrel sweeps, get tone both ways, one direction shorter than the other tonally. (Right to left sweep has shorter tone)
Turn iron bias to level 1, still get tone both ways, but in one direction barely discernable (Right to left sweep is shorter)
Turn iron bias to levels 2, 3 and 4 all you get is trailing tone as coil is swept left to right.
Turn iron bias to level 5, dime goes by by- Notta
Testing was done with some coil height too.
Another test.
Clad dime with nails turned (the easy way) for detection of dime.
Again park 2 factory disc speed 6.
Iron bias 0 gives good signal.
Iron bias as it is increased tone provided gets slightly more and more short (forced sounding)
I can detect dime 2 way sweeps with tone up to level 4 iron bias setting,
Level 5 iron bias. Two way sweep tone goes away.
This test also done with some coil height.
Now some here maybe thinking, can I speed up Equinox and gain all or part of what's lost with higher iron bias. You will likely never gain all, very possible to get a smidge back tonally though by speeding up. But remember higher speed means less depth. And speeding up can bring shorter tones (harder to decipher).
Iron bias setting, one might think it just affects Equinox performance around nails and iron. Is this so?
According to my test, nope.
Another test with pic.
You see the clad dime and pull ring and tab on both ends.
Park 2 speed 7 iron bias 0 I get this dime good tonally.
If I dial iron bias to max 9 setting, Equinox ability tone wise gets cramped. Dime can be heard but remember I know the dime is there.
Tonally transition is compromised when coil comes over lower conductors here and approaches dime.
I won't go into more detail here with additional settings and outcomes.
Iron bias doesn't seem to affect Equinox with Equivalamt settings wise when comparing nonferrous coin and say lower conductive junk object as much vs a nonferrous coin and iron..