Field Test Report on the XP ADX 250 Metal Detector
Writing a constructive field test is relatively easy, however because of the limitations it can generally end up reading as the same old same. Let’s face it; it’s a detector; which is not really something that’s in the “salivation league” as a Ferrari. At first glance the XP250 seems to be the “same old same old”; it’s the updated version of the adx 200. Whilst still clinging by the slenderest of threads pertaining to cars, it is not only updated, but has also been up rated; it does for the 200 what the Power did for the Goldmaxx. (Just a tad more than your ordinary VaVaVoom.)
The XP 250 still operates on a frequency of 4.6KHz, however it has now been equipped with a new motherboard and a different filter system; thus making it faster in the response and also the recovery speed over the previous ADX200. The other difference when looking at the control box is the frequency and channel shift. This three position toggle switch enables detecting partners to choose separate channels for their headphones enabling them to work in close proximity without the usual electrical interference. The new machines are already chipped to accept either the cordless back-phones or standard ones.
One other feature is the new material used for the scuff covers on the coil these are significantly stronger than the previous type. The overall weight of the machine remains the same.
Just a few words about the 4.6 KHz frequency machines. The lower frequency machines have the ability to handle the mineralisation better and also have superior discrimination due to their ability to recognise iron far easier than their higher or multi-frequency counterparts. The forte of the low frequency is stability over most ground conditions and superior depth on the larger thicker coins and objects. The trade off (yes there has to be one), is a slower recovery speed and less sensitivity to smaller thin sectioned coins and objects. This is not to say that they WON’T pull them if they are under the centre of the coil, it’s just that the higher frequencies do a superior job. I could describe it as the low frequency is being banged in with a lump hammer, whilst the higher frequency uses a toffee hammer. (A pulse uses a sledge hammer).
Controls
This is a straightforward, easy to use machine, having one pot for the Sensitivity and another for the Discrimination.
Sensitivity. This can be run at the preset mark on all but the worst of ground conditions without any hint of chatter; giving very good depths especially so on the larger, thicker coins and objects.
Discrimination.
Another three position flick switch allows you to use All-metal, Disc.1 or Disc2. A rotary pot will enable you to turn either Disc to whatever the discrimination levels you require.
Disc.1 utilises the outer grey ring on the disc setting, starting with an extremely low level and even fully turned will still only knock out larger iron.
Disc.2 uses the inner red ring to save any confusion. At the lowest setting it takes over from where disc.1 left off and increases by turning clockwise. Bear in mind that the ultimate settings for discrimination on all the Xp machines are far, far lower than other makes. The discrimination system doesn’t waste filters with bottle caps or pull tabs, it has an expanded discrimination where you need it, for iron and coke. Simplicity itself.
The eight 1.5 volt batteries sit in the drop in pods and will provide you with a good 40 hours usage.
Out in the field. Celtic/Roman.
This field is moderately mineralised with a heavy concentration of ferrous in certain areas, but relatively clear in others. The persistent rains over the previous few days would increase the level of interference from the mineralisation; so putting on my "sensible" hat I went with the standard nine inch double-D widescan coil.
I was aware that although the 250 was “faster” than the previous 200 it would still be advantageous to work slower in the worst of conditions. Signals from small targets were coming up, but it took a little while to trust the level of discrimination that I had set especially with just a single tone signalling all types of metal content on the targets. Anything that was a little bit doubtful was simplicity itself to verify just by flicking into the all-metal mode; this, if iron would give a louder and broader signal (if near surface, lift the coil.) One fault that I did find was that working in the “busier” conditions you really had to concentrate when listening for the deeper quieter signals. After a phone call to the manufacturer in France and discussing the problem, I was sent the new V4 chip to insert in the control box; problem solved! This might be construed as being over fussy, however I was on a field that has produced small Celtic silver and gold and I would be damned if I was going to leave any of the deeper ones for my friends to find with their high frequency machines! 
The Sensitivity level could be run just before the preset mark on the clearer areas and then dropping back a tad where the ferrous was more concentrated. The same with the Discrimination system, most of the time the 250 behaved comfortably with a setting of about 2o’clock in Disc.1 (small nails); then moving it to the lowest setting in Disc.2 (still only larger nails) for the busier ferrous areas. Even if put at a much higher setting than this, say to discriminate “coke” for example, there is little chance of losing any of the good stuff.
In most situations it was possible to get an idea of the depth of the targets by the volume and breadth of the tone. The deeper the object, the more narrower and quieter the signal became; without the normal loss of tonal quality. This I found was very important, as on some machines the signal starts to break up when approaching near maximum depths.
The improved recovery and response speed of the new ADX250 is a real confidence booster when trying to wheedle out finds amongst the iron. I’m not trying to claim for one minute that it’s as super fast as its 18 kHz brethren, but the 250’s superior performance in these conditions is certainly noticeable compared with the old model and the amount of smaller finds proved this to me. Saying this you still have to recognise what is going on under the coil and slow the sweep speed accordingly if you want success.
Pasture land.
These conditions and a low frequency detector go hand in hand. The higher frequencies will find there is no doubt, but they don’t "cut it" for me like a low one. I stuck on the 11inch DD widescan for that little extra coverage and hopefully depth. Recovery speed isn’t the be all and end all when out on the grassland (in most cases), ground coverage and depth is more the criteria. It felt good to make a change from the normally busy ploughed sites and get a bit of relative peace and quiet on this particular bit of pasture. The Sensitivity could be set just beyond the preset mark with no hint of chatter and the Disc.1 control was set at about 1 o’clock.
It wasn’t long before I changed to the All-metal mode just to hear some signals! Checking these with a flick of the switch into either Disc.1 or 2 was simplicity itself. Buckles, horse furniture and old coppers started making their appearance, depths on one or two of these pieces would be what to expect from a low frequency detector, “blinkin’ good”. At the end of the session I was more than pleased with the unfussy way the 250 went about its business.
Mineralised Site.
I have been spending some of my time detecting in woodland, there’s only about 30,000 acres of it to go at! Some of the ground conditions are straightforward, but there are quite a lot of places that I’ve come across that are far from these. Just a very thin layer of poor soil which then turns to grey sand and then to orange sand, when this is wet from top to bottom be prepared to struggle; finds are limited to the top four inches or so even on the larger coin sized objects. Signals can have an "iron" quality about them and I’ve heard many a time that "you need to dig everything if you want to do any good". This maybe so with a multi or high frequency machine, but if you are going to detect in these conditions don’t hamper yourself with them just because they are the bees knees for you on ploughed soil. Get yourself the right tool for the job, a low frequency will punch through that mineralisation far easier and recognise iron so much better. I admit that my first forays into the woodland was with a high frequency and yes I did make finds but I soon became aware of the distortion of the signals on some good objects. If it was ploughed soil, there would be no way that you would bother digging these sounds and bear in mind at only three to four inches maximum in depth.
I was invited to one such site and took along the 250 and quite literally within the first five paces I pulled a couple of Roman bronzes. Nothing unusual in itself, apart from the fact that this was the only entrance to the site and it had been walked over time and time again with high and multi-frequency machines. It was a bit of an eye-opener for all concerned and it continued throughout the days detecting. I was continually being asked to check signals and a couple of sweeps of the coil was all that was needed to verify a dig or not. That is not to say the others didn’t make finds, because they did, silver included; but it needed that high level of conductivity of the coins near the surface for them to make the finds. The Adx 250 had the ability to find the deeper targets beyond their machines capabilities. Impressed? You bet they were and it was only my second day out with it!
However "one swallow don’t a summer make" but this machine was beginning to give me real a sunny disposition.
Conclusions.
Just a quick word about the V4 chip, I might have seemed to have been "over-picky" in wanting to try it. Under almost all detecting conditions the V3 chip worked absolutely fine, but as I was field testing the Adx250 and found a situation where I thought its performance could be improved, I thought that I would give it a try. As I said it was a one-off situation and for most situations the average detectorist will be hard pushed to notice the difference whichever chip is fitted. (The XP manufacturer really does listen to the detectorists’ feedback and are continuously making improvements to the detectors efficiency; these chips can now be fitted to all existing models for the derisory sum of about a tenner!)
I have been impressed with this machine, so much so that I now own one. Despite the low price tag, I rate this as one seriously good detector. I’ve taken to calling it my black and white machine, there is no messing around with "is it, isn’t it" signals; it is either yes to dig, or no to leave it be. The old ADX200 had a very good following of devotees, with the new improved mother-board and filter system that gives this a faster response and recovery speed, and I fully expect the same to happen with ADX250. This detector delivers in conditions where it shouldn’t and does a masterful job where you would expect it to. If you equate £’s with power, you will overlook this detector; that unfortunately for you, will be your loss. In my book it has the three S’s, Simple, Straightforward and Successful; need I say more? The ball is in your court.
John Lynn