I am plagerizing here but I pretty much am in line with this post by lowjiber and it's very good info for the MXT user.
Quote from: Tin Nugget on February 09, 2010, 08:20:13 PM
Most people I run into using an MXT do not take advantage of how hot you can run it, +1 +2 +3 and really don't pay attention to subtle rises and falls in the threshold when there is no VDI so they miss out on some deep stuff. Run it as hot as you can stand it and when you notice a rise and fall in the threshold on a sweep and get no VDI and it's a repeatable rise and fall, use your pinpoint, it will probably be 10 inches or so deep, dig it up!
I totally agree, Tin. I believe in running the MXT on "the edge of insanity"...deep targets. Below is a little excerpt from a tutorial I put together for a new MXT'er once...
I can’t emphasize enough how much a really good headset will help with the MXT. I use Killer B Ultimas (with leather ear cups). There are others just as good…Ratphones, Jimmy Sierra Maxiphone II’s, etc.
Three Keys to success: The key to whispers lies in the Threshold. The key to discrimination (disc) depth is to get the gain as high as possible in the given soil conditions. The key to using threshold and disc together is to get the machine in a stable, mixed-mode audio configuration that will take advantage of the tremendous power of the MXT.
Below is a quick-n-dirty way to get started with your MXT. Remember, our goal will be to get the machine as stable as possible with a gain setting that’s as high as possible too.
Here's a way to start learning...
1. Put the mode switch in Relic Mode and flip the trigger FORWARD to put the machine in Alternate Relic Mode...leave it there unless you're hunting gold nuggets. (See notes on Alternate Relic Mode below.)
2. Start with the gain set to 10...you're going to "move up" from there toward 3X. Keep in mind that the settings in the 1X-3X range are orders of magnitude higher in gain. In other words, 1X is ten times as “strong” as a setting of 10 (right next to it on the dial). Depending on your soil conditions, you may not always be able to get the machine stable as you approach 3X…that’s why we’re approaching it slowly.
3. Set the disc to the first triangle (this allows everything except iron)...leave it there.
4. Ground balance the machine per the manual. Before you start the GB function, pull the trigger to ensure that there is nothing below your coil. This is the key to getting the machine stable.
5. Adjust the Threshold so the machine just hums. This "hum" is the all-metal mode that will let you hear things that are too deep for the machine to accurately identify with a VDI. You'll hear the threshold slightly rise as you pass over one of these deep targets...the famous "whispers".
6. Swing the machine a bit and if it's stable...kick the gain up toward 3X about one step (1X, 2X, etc) at a time. As long as it's stable (no jittering, or false VDI's) you're in the MXT Zone.
When you are swinging as described above you are effectively in a "mixed mode"...all-metal (threshold) and discrimination (VDI). The VDI and the disc "tone" will be pretty accurate.
Remember, the Voltage Controlled Oscillator (VCO) will cause shallower targets to be louder. That's why you bought a good headset. KB's (and other good headsets) have a "limiter" switch that keeps a quarter at ground level from knocking your head off when hunting in a high gain configuration.
If you're having a nice stroll and you hear a "whisper", immediately crank the gain to 3X (regardless of the noise) and try to get a VDI. (More on this below.)
The MXT is such a favorite because the user can easily adjust threshold, gain, etc. rapidly over a potential target.
Alternate Relic Mode Notes:
It undoubtedly seems strange that I recommend using Alternate Relic Mode (ARM) for everything. You’re probably thinking, “I’m not looking for relics, I’m looking for coins and jewelry.”
ARM is an interesting twist to the MXT. It places the machine in a “mixed mode” audio configuration that allows the user to hear both the all-metal and discrimination signals. We kind of covered this previously, but there is one thing that sometimes bothers new users about ARM when hunting for coins and “bullets, buckles, etc”. ??
You don’t really care what the target description is anyway. The key is that the VDI number reflects the nature of the target. Quarters are still going to be in the low +80’s and pulltabs are still going to drive you crazy in the lower VDI ranges. It won’t take you long to figure out that nickels are usually in the +18 area; quarters are +82; zincolns are +55; etc.
Stick with ARM…it has some real benefits.
Whisper Notes: Don’t get overly excited about whispers when you’re just starting out…they’re few and far between. However, hunting in ARM with the threshold just humming in the background will give you a depth advantage over those who don’t focus on everything in the headset. Besides, that’s why you bought that $125 set of headphones…might as well use ‘em.
A whisper occurs when the coil passes over a target that is too deep to be accurately identified (via VDI) by the machine’s discrimination function. When the disc is able to correctly give you a VDI reading, you don’t hear the whisper because the disc tone is yelling at you…drowning out the slight rise in threshold.
So, what do you do when you hear a whisper? You’ve got a couple of options, depending on the gain setting…
If your gain is not set at 3X (maximum gain), immediately turn the gain knob fully clockwise. Pay no attention to any strange sounds coming from the MXT…we’re trying to get a VDI reading from the disc channel and could care less about stability at this point. Remember, we already know there’s a deep target under the coil…we just want to see if we can figure out if the target is non-ferrous or not. If you get a VDI that shows something like a coin…dig it. It’s that simple.
If your gain is already set at 3X, I guarantee the target is extremely deep. Turn your dual knob (discrimination function in ARM) into the ferrous range (below the first triangle) and see if you can get a VDI. If you do, the target is iron and it’s up to you whether you want to dig it, or not. If you don’t get an ID then, you’re well advised to dig a hole and recover the target…I guarantee it’s not a pulltab.
In summary, this small glimpse into the world of the MXT is hardly the end of the story regarding the learning process. I trust it gets you familiar with the common terms and their history. The rest is up to you.
The "alternate" (switch forward) function in Coin & Jewelry mode is completely different from the "alternate" function in relic mode.
In C&J mode, the switch forward serves as a "notch" that eliminates many of the VDI numbers (+28 to +49), and the user will indeed miss opportunities to dig gold targets that reside along with the dreaded pull tabs. (Personally, I would never hunt the MXT in "Alternate C&J" mode for the very reason you described above.)
However, the "alternate" switch position in Relic Mode serves a completely different function. Simply stated, Relic Mode has no "notch". The setting of the Dual Control knob determines the audio response. Set it on "3" and you will always get a response to any VDI above zero, regardless of the position of the trigger. The function of the trigger in relic mode is basically designed to change the speed of the Self-Adjusting-Threshold (S.A.T.).
The ground where I hunt (California, Nevada & Arizona) is very minerialized and can literally change under your coil from one side of the swing to the other. Since I prefer hunting the MXT "on the edge of insanity" and depend on the threshold for "whispers", it is important to me that the S.A.T functions fast (Alternate Relic mode) to stabilize the "insanity" that is going on in my headset.
(I should note here that a slow swing speed in normal Relic mode will produce similar results. However, there is another advantage to the "alternate" mode that I particularly like...described below.)
In Primary Relic mode (switch in middle position), VDI's above the level determined by the Dual Control knob give off a high-pitched sound and those below give off a low-pitched sound.
In Alternate Relic mode (switch forward), all VDI's below the Dual Control set point are silent. VDI's at, or above, the Dual Control set point are broken down...high pitch for non-ferrous targets and low pitch for ferrous targets.
Since there are a lot of things going on when hunting "on the edge of insanity", I like the additional "organization" of the low/high sounds that the alternate position provides.
I hope I've answered your question. In my initial posting above, I've tried to provide a basis for pushing the MXT to its limits. As experience and hunting locations change, the user will (hopefully) go beyond my initial suggestions.
