- Posts: 713
- Joined: Wed Aug 18, 2010 8:04 pm
- Location: Hampshire
First of all I think its best to explain that I have only used the GMP for 4 sustained sessions, roughly 7 hours per session. This is therefore not an expert or experienced user review, instead its just my honest opinion about my likes and dislikes of the machine, from my very limited experience of using it.
I bought the machine solely for better performance on heavily iron infested ground. I read the reviews on the machine and spoke to users of it and it became apparant it was one of the best machines for the job in my price range. The previous machine I was using was very good, I loved it, a Sovereign GT, but after a session of complete nulling in a heavily iron infested field, I decided to make the move.
So, first thing to remember there is no meter and the machine is tone only. This was no issue for me coming from the GT, although I had a meter on the GT, the meter just acted as confirmation that the tone I was hearing was not iron.
The machine is light and no need to hip mount the box, I can swing all day no probs. Hip mounting would obviously make it even lighter.
The headphones are back headphones, so comfortable and also wireless. Trust me, if you have not used wireless, then start doing so. Makes life a whole lot more easier! My machine also came with the standard wired back headphones. Again really comfortable but connect you to the machine, so sometimes limits your ability to move and dig etc. Having only used the wired headphones once I think i was getting better clarity in the tones, but i might be wrong.
I invested in 16 rechargeable batteries costing £17 off ebay and £10 for a battery charger, from 7 day shop on ebay, they charge 4 batteries in roughly 2 hours. The machine takes 8 AA batteries by the way (btw).
My first session was on pasture, I had not even read the manual, just put every setting at 12.00 and silencer at 1 and off I went. It noticed that the machine was picking up everything, all metals, there was no nulling. So small iron was giving a low buzzing tone and large iron a medium tone. Occasionally the medium tone was broken and had a buzz all the way around it. This turned out to be big lumps of iron each time. I probaly dug about 5 large peices of iron thinking it was going to be a decent target. High tones were easily recogniseable and a must to dig. So i came home thinging not bad, but confused about these medium tones.
I then watched the DVD Roger the Relic back to basics which is solely about the GMP. (Thanks Earthmover for lending it to me) If you are new to GMP watch the DVD - you learn lots! It almost has 1 hour worth of Roger swinging his detector and listening to all the tones - invaluable!!
One of the most important things that has ever been said to me is to check every signal a second or 3rd time at 90 degrees. A small nail will give a sweet medium tone on one swing yet a low iron buzz on the 90 degree swing. Time to move on to the next signal. Every target I now dig will be checked from a whole host of angles!
I now have been able to work out the difference of the middle decent tone and the middle iron tone for big lumps. There is a very suttle difference that I have now picked up. One thing I cannot yet master though is the tone for coke. I have never detected coke before on any of my machines but the GMP loves it. Experienced users say they can tell the tone, that will have to come in time for me as every time I go over it, it sounds like a sweet signal. I spoke to an experienced user and he said just to put the iron threshold in Auto and it will buzz like iron. I questioned about losing depth and recovery speed and he said it will lose you half an inch and reduce recovery by a nats bite. I tried it on a field swamped with coke and it worked, I was still digging decent targets next to iron and at good depth and my coke was giving an iron buzz.
Depth initally was a concern, until my last session. In my last outing with the GMP i must have dug 70 holes, on pasture and only 3 times was the target in the clod, it was always still in the hole with plenty of digging left to do. I was digging deep clods too. In one hole I found a tiny air gun pellett 7-8 inches down and in another a buckle a good 9-10 inches down - perfect, and it was giving nice solid tones on both occassions.
So these are the settings that I use on coke filled sites:
Iron Volume= 1 oclock
Ground= 11 oclock
Silencer= 1 - makes the tones a lot clearer
For fairly quite fields with little coke and a not a great amount of iron:
Iron threshold= between 7 and 14 dependant on how much iron
Sensitivity= between 1 and 2 oclock
Ground =10-11 oclock
Iron Volume = 11 to 1 oclock
Now, i have not tested my machine in the garden with different settings and different targets. So in effect my comments on my settings could be completely wrong! All i know is that in my last outing i dug 1 piece of iron that i thought was going to be iron and the rest were all decent targets such as lead, shot gun ends coins etc all at decent depths. I have so much more to learn about the machine and proper garden tests with different settings and metals should prove really invaluable.
Things to remember:
The machine loves coke.
Check every signal from a different 90 degree angle.
wireless headset and lightwieight machine is a pleasure to work with.
The machine will detect all metals and has no meter.
Hope you find this useful