Andy --
l want to disagree just a tad, with part of what you are saying. Please understand that I mean no disrespect; I read your book on the Explorer/E-Trac, and am currently reading your CTX book. As such, you have taught me much over the years -- and, you have many multiples more years of experience than I do. I respect your knowledge, insight, and experience greatly.
With that said...
I have to disagree a bit with one of your points.
I agree with you that there is valuable information to be gained through side-by-side comparisons on undug targets, with different machines. No doubt, if "new machine A" locates a target, you mark it, and then grab "old machine B" to give a listen, and it either cannot detect it (or can barely detect it), then that
certainly tells you something important about "new machine A." And I also agree that many times, with "new machine A," you are likely to come across targets that it finds, that were simply
missed before, and which ANY machine would have found, had the coil passed over the target. Similarly, when using a new machine and really trying to learn the numbers, tones, etc., you often will dig targets that you would have PASSED on, with a more familiar machine, but are "curious" about with the new machine, and thus you dig "just to see" -- and the target turns out to be a "keeper." Almost every time I am learning a new machine, or new coil, I will make several of these, what I call "unusual" finds -- keepers, but ones that I likely would not have dug, had I heard them on the "old" machine/old coil. SO -- your points are well-taken. Before we can decide that a new machine "is finding targets the old one didn't," some direct comparison with the old machine -- on undug targets -- can provide some "validation" of your impressions of the new machine.
BUT -- where I disagree with you a bit is that I DO NOT think that there are not conclusions which can be drawn WITHOUT direct comparison to your "old machine." I DO think there is potential value in just "seeing what the new machine will find," and if it is "finding" a good many keepers i
n a site you are familiar with, that you know has been heavily worked...and
if you have a solid feel for what it "normally" produces on a given hunt, there is some subjective, qualitative, but still potentially valuable info there, to be gleaned, regarding the new machine.
To elaborate...there is a park in particular here locally that I have hunted for years. I know this park like the back of my hand, and know what it will produce on a given hunt -- as I have a HUGE sample size of hunts from the past, such that I've gained a feel for this park's "potential," on average. There are, virtually, NO easy targets left (sure, there are a few, but it would be an extreme rarity). Virtually all targets left here are either DEEP, or MASKED -- to the point of being barely, if at all, detectable for me, and my Explorers.
Now, IF I take the Equinox to this park, and were to begin to dig 4-5 keepers, per hunt, over several hunts, then that right there is unusual...and it SAYS something. Because one, MAYBE two keepers should be all I'd expect in a given hunt, AT BEST, and ESPECIALLY averaged over several hunts. But, anyway, back to the point...if I were to then mark these suspected "keepers" found with the Equinox on one of these hunts, and then bring the Explorer out, and check the targets before digging, even if the Explorer "sees" all the targets, that does not, of course, mean that it would necessarily have found them "in real time." I think you'd agree there is a difference between LOCATING a target, during a hunt, that stops you and causes you to investigate, versus KNOWING there is a target there, and working the machine until it "sees" it.
I'd like to share a story, that will illustrate this. Back when I was less experienced, I was swinging one particular machine, while all my hunting partners were swinging E-Tracs. We'd go out detecting, and they would CONSISTENTLY dig a couple of silver coins and several wheats each, with VERY little trash in the pouch, while I would end the day with plenty of trash, and either no keepers, or perhaps a wheat or two at best. This happened for WEEKS. After awhile, I realized that my problem was NOT depth, but ID...my machine simply was not providing me information that MY brain could interpret as a "dig me" signal. My machine was plenty deep, but it was poorly IDing deep targets -- both audio and VDI -- making it hard for me to sort the trash from the treasure, in "real-time." So, I'd spend way too much time bogged down interrogating, and digging, deep trash, while my partners were cruising along, largely digging only "good" targets. During this time, we were all in the habit of "checking each others' targets," pre-dig. And when we'd do so, and my partner would say "here, listen to this one, I'm pretty sure this is a 7-8" silver dime," there was NEVER a time when my machine could not "see" the target, and indicate its presence. And most times, if I worked the target enough, I'd get some high tones, and a few decent ID numbers at times, such that I could eventually "coax" a "silver dime" reading from it. BUT -- "coaxing" that silver signal from an already known target, is NOT THE SAME as working your way through a trashy park, and accurately locating the GOOD targets, while ignoring the bad.
The "rest" of that story is, I eventually switched to an Explorer SE Pro, and after a few hunts of learning the machine's tones and ID numbers, I began digging keepers consistenly. The first "good" hunt with it, two weeks after I bought the machine, I dug two silver half dollars, a ring, and a few wheat cents, and from then on, I was able to much more closely match the success of my E-Trac-swinging partners. The final 7 months of that year, produced 54 silver coins for me...and I say that to illustrate that while I know my "prior" machine would have "seen" every one of those targets, it was the SE Pro that was able to much more accurately
alert me to their presence during the course of normal hunting...
So -- while I largely agree with you, I do not necessarily think "seeing a known/previously located target" with a second machine means that the first machine didn't do something "special" or "unique" or "new." If I take an Equinox to the park I speak of, and can consistently locate, and dig, three or four keepers somewhat routinely, I GUARANTEE that would mean that the unit would be doing something -- at least for me -- that my Explorer was NOT. It would be giving me some additional clue, be it audio, or ID, or something, that was more consistently catching my attention and causing me to stop and investigate than my Explorer did. And that tells me something. AND -- I would expect that on MANY of those targets, I COULD get the Explorer to "see" it...but again, SEEING a
known target, and alerting me to the presence of an
unknown target while in the course of a hunt, are two different things...
Steve
EDITED TO ADD -- while I was typing this long-winded post, Rich(Utah) posted something much shorter and more succinct, that says largely the same thing as I did. Nice job, Rich -- I agree with you! 
