Book Excerpt:
2/ The Anfibio’s Strengths: Audio
Every Nokta / Makro detector I try seems to have better, cleaner, more informative audio than the last. The Anfibio is also what would be termed a “high bias” detector in that when you learn to listen for extension in the response–you can become very accurate. This sharp, clean audio lets you hear a real lot of detail about what is under the coil. There are several U.K. “YouTube” videos out of hunters placing nails right on top of coins and still being able to detect the coin with the Anfibio. This is a great demo of just what this machine’s fast processing speed and high-bias performance can do for your find count at old sites.
I credit the operating characteristics of Nokta /Makro detectors with teaching me how to effectively use coil control target testing. This has found me a lot of deep gold and silver. With the speed and “clean” metal bias of a machine like the Anfibio this testing is much more effective–that is, when you use the coil to check a signal by going to the “cross-sweep”–iron and other corroded targets don’t “stay in.” Misshapen objects like scrap lead or “can slaw” are also more likely to give a broken tone. Again, good, non-ferrous responses have “extension.” What I learned was that there’s a whole other level of skill building, accuracy and effectiveness available to you with this clean audio and super-fast signal processing.
Other strengths of this detector include a great display that lets you make fast adjustments for more exact tuning or “ID-ing” This also lets you jump from mode to mode instantly to cross check responses. You can move between different frequencies (5, 14 and 20 kHz), audio modes, and recovery speeds in an instant. There’s also a versatile Discriminate package that lets you manage your target selection with accuracy.
This also a very deep and powerful detector with great small object sensitivity. The reason for this is because the Anfibio features high Gain circuitry. Gain acts to sample a tiny part of the returning signal and amplify it. This small sample is easier to manage in software and more of the distortion can be removed. So you have a cleaner, deeper signal. This means that small targets are amplified (or boosted) as they are received. Like many detector features–this is a “two-edged sword.” While small and deep responses are brought up to where there can be heard, other non-so good signals that are just across the “line” into the iron range are also amplified and may be “pulled up” to mimic good signals. For the beginner, this can be confusing as iron targets and even a few foils and crown caps are “hopped up” and may indicate as coins. However, the good news is that once you learn a few simple basic “fixes,” the downside of this tradeoff about disappears and this extra deep object punch becomes your best weapon. This takes practice, bench testing and time in the field. You could call the Anfibio a “Gain heavy” detector in that even at the presets-there will be good sounding false signals–from spikes, deep iron and some bottlecaps. As will be detailed further on–a good beginner strategy is just to “turn it down” and do some familiarization in 2 Tone audio mode. Even running at a Gain setting of “55” or “60” is a not a bad idea. This simplified less “amped up” audio will respond to these falses in more recognizable ways. An intermediate stage is to have one search mode with preset or higher Gain and a second weaker setting–to see how signals respond with less Gain. Going between the two is a great way to really get a feel for how Gain goes deeper–but at the same time brings with it considerable distortion. Targets sound fuller and better at high Gain settings. Where you see a response disappearing completely –or becoming broken in the low “checker” mode–suspect iron. Where a target just becomes weaker–this has a better chance of being a good, non-ferrous target.
Gain also acts to “fill out” small responses–making them sound bigger, fuller and better. This makes for what I’ve heard termed a “steep learning curve” for the novice as there is the urge to go after a lot of sounds that are too small to be good targets. What helps is to gather more information than just “meter and tone” using the coil and the Pinpoint control. This lets you place your signals in context–to focus on the size, shape and location in the strata of each signal. When you learn to do this–each signal feature acts to confirm the others–giving your accuracy and conclusiveness a huge boost. For example there is nothing better than hearing a high silver tone, seeing a “92” on the meter and then getting the confirming narrow Pinpoint response that indicates a non-ferrous object. I call this the “In Keeping” method. (More on this later).
Another effect of high Gain circuitry is that the detector is more likely to sound off on unusual variations in the ground. These can be patches of black sand or anything that represents a big change. So the ends of spikes, twisted wire or aluminum shards can all “sound off” on your first coil pass. This is where coil control comes in in that these are not consistent targets and will change or disappear on the cross-sweep or with varied coil passes.
Another great thing about the Anfibio is its stability. Where there is not much interference from electrical sources it’s possible to run this detector at almost full Gain. However this type of setting has a downside too in terms of the false signals that it brings up. This is where learning some of the basic skills covered in this book can be of help–letting you mediate this high power with accurate signal type recognition and checking methods. Even where you do have a lot of interference–it’s possible to run a “balanced” signal so as to be able to hear good targets though the noise. From:”Successful Treasure Hunting with the Notka / Makro Anfibio Multi Metal Detector. by Clive James Clynick
Reviews at: clivesgoldpage.com