I'm with John. GTA PM's were good units. If you want to change up, you can get different coils for it like a sniper or a large, "plate" coil. This will enhance its versatility and is a wise dollar spent.
Most of the new detectors have gone to ever micro-sized, high gain electronics, and effectively larger coils. This reduces their power consumption and battery needs and allows them to cover a wider area per sweep. It gives them a slight increase in depth potential, too. In the low and mid price range, this also allows them to add more of the 'big bang' features of more expensive models. Things like auto ground balancing, multi-toned audio, pre-programmed hunt modes and so on are more common now in even the low price units. They've also gotten tougher and lighter.
But much of the ballyhoo over depth increases is just hype. In theory, we should be able to double the width of the coil in realized depth penetration.
Sadly, much conspires against us in this. A larger coil normally does get you some depth increase, but there is a trade off. As we increase the coil size, the ability to separate targets from each other when more than one is beneath the coil decreases. More on that in a minute.
But in terms of pure depth, the "Cone Effect" is one of two things that we struggle with the most. Our own beloved Uncle Willy has written about it at length.
Essentially the field of a detectors' coil behaves like an inverted cone. So, at increasing depth, there is less and less of the field to detect the presence of metals.
At its extreme lower point, you may only have an inch (or less) of usable field strength to detect targets with. This is why going slow, at the right sweep speed and overlapping your sweeps is so important. More often than not, we also punch up the SENSTIVITY to try and offset this. This also hurts us, essentially overwhelming the detector in the presence of ANY targets.
And what about target response? Trash has the bad habit of masking the detectors ability to "see" the good stuff. By trash I mean anything that is not "valuable."
Very few detectorists have the good fortune of hunting pristine earth, without trash targets to muck up their efforts. SO, most hobbyists use way to much discrimination, in the persistent belief that their detectors will ignore this trash and "find only treasure."
But, in discriminate modes, any trash within the detection field (even small bits) masks - or skews - the detectors ability to detect or quantify a target.
It may actually make the good target invisible to the detector. So in masking out pulltabs, you risk eliminating nickles or rings, etc.
And metallic alloys also "mix" within the detection circuits. A blob of foil next to a dime, for example, may come out looking like a zinc cent. You'd be tempted to leave that behind.
Iron trash is the WORST offender. Ferrous alloys are the marker of mankind's activities - where you find ferrous alloys, you find the presence of man.
In the relic fields, one way you know you have found a long forgotten site is by finding iron trash like nails - ON PURPOSE.
But coinists and jewelry hunters consider it worthless, so they discriminate it out, too. What they don't realize is it plays havoc with detectors.
Even small amounts can impact your coil, at a wider distance than the coils own width. This means that many targets will flatly be missed - or mis-identified. In fact, if your Garrett detector starts getting squirrely on you, popping and burping, open up the iron range discrimination. I'll bet you've stumbled into a nice patch of ferrous alloy trash.
What is needed is a detector that can see a dime within 2 inches of a nail at under 4". I've only found a few detectors that can do that, and the Garrett's come mighty close. This includes your GTA 1000. Add a smaller "sniper coil" and you get into this realm.
Spending $600 to get a new detector wont necessarily buy you better performance. You may see an incremental boost in depth, or you may not. It may separate targets better, or not. In a side by side comparison, you may see some user features that impress you. And the construction may be both lighter and handier.
But you probably won't see a significant jump in raw performance over your GTA 1000 PM from any detector.
