The DD gets between items better but in your case you really are wanting to dig everthing since anything could be a potential relic. I would go with the bigger deeper concentric coils. Setup from another posting follows.
I can tell you how I run the MXT PRO. I am primarily a relic hunter in south jersey and have found a lot of relics including coins in the over 12"" range silver and copper. In fact we have been really rewarded in doing fields that have been repeatedly hunted over the years because of the depth we are able to get.
1. Here goes. keep it in relic mode....
2. turn your gain up to the pre set marker and ground balance...
3. remember after you think you have it ground balanced lift your coil waist high pull back the trigger as if pinpointing and lower it to the ground....if the threshold sound increases significantly then ground balance again....once its ground balanced set to the lock ground balance...
4. now on tones use the all iron ID..... this is basically no discrimination......however it will give you two tones....grunt for iron and a beep for anything above...
5. now max the gain out and have at it......
because there is no volume control its best to buy earphones like the sunray pros...they have a limiter switch and volume controls on them...this way you can turn up the volume on the earphones so you can hear the whispers yet they also have a limiter switch so when you hit a good target the sound wont blow your ears off.......you have to really listen....sometimes it might just be a rise in threshold...in which case pop out a shallow plug run the detector over it and see if you can get a signal....sometimes it might be the weakest beep you ever heard...if you ever get a grunt and a tiny beep along with it see if the beep keeps coming up with the grunt especially when you change direction of the coil sweep...many time these will be deep buttons. if you ever get a signal and when you pop the plug its not in the plug yet when you go bak over the hole its not in there either....dig more dirt out and keep checking......a lot of times on small deep targets...like 9-10 inches deep when you take the dirt from on top the signal dissapears...so dig deeper.....if you find an area with a lot of iron....turn your gain down or the iron signal will overpower anything laying near it...once your clear of the iron turn it back up......i'm talking a lot of iron now....like multiple iron signals every swing........once you scan your area and you have an idea where you want to hunt get that coil down so your skimming the ground and go low and slow ... one more thing ..the reason why you lock the ground balance is so you wont lose a deep weak signal when you go over it a second time......trust me if you leave it in auto it will cancel it out......keep in mind that the MXT pro constantly updates the ground balance in the computer even when you have it locked...so every so often after youve swung the detector over clean ground just hit the ground grab button and it will update the ground balance to the current setting even though you have it in the locked position......I promise you if you if you use these settings and learn how to listen to the machine you'll find more than you ever thought.....I dont use anything but the 12" concentric....even in trashy areas and have done fine.....just the other day i found a gold ring from the 1700's at 5 inches with a piece of iron under it... it was one of those times with a grunt and beep.....I've went behind some of the latest high dollar detectors and found things that theirs missed...you cant be lazy and you have to dig those iffy signals and you'll be rewarded. Oh one more thing....forget VDI numbers and the screen ID.....just dig all good signals...and remeber anytime on any machine if you use discrimination you lose depth.
LOL...thanx.....most targets unless they are 5 inches and under wont vdi correctly...especially if your the gain is maxed out..... I know its hard not to look at the screen but ive found alot of nice coins [ especially small silver like 1/2 reales] by just going by sound ....if i had gone by the screen i wouldn't have dug .....i have found plenty of relics deep especially at 1700's sites that were deep plowed in the 1800 and 1900's ...Topo is right most relics and coins are in the 6 inch range.....however since we have learned to run our detectors like I stated we are having greast succes going back over sites that have been pounded for years...we are currently doing a revolutionary skirmish site and when i asked the owner of the property for permission he said yes and chuckled at me.......needles to say in the 8-12 inch range we have found close to 30 musket balls...ramrod tips. ..gun parts.....buttons...ect. ..and the coin finds have been unbelievable as of now close to 80...everything from liberty caps..[ from around a long gone house]...to drape busts, spanish silver and early colonial coppers ...we even pulled out 4 civil war buttons.... ...lol......i made the property owner a nice display from some of the stuff and during our conversation I asked him why he laughed when I had asked him permission......he stated that he never thought we would find a thing as over the years he lost track at how many times the place had been detected...I always knew that the settings we use were spot on ...but to hear that just reinforced the fact that most people set their detectors up in such a fashion [ using discrimination] that it takes depth away.........i want the coins buttons jewlry.... lol..... that the others leave behind....sure your going to dig some trash targets that fool you...but look at it as exercise.......the most common trash that puts out good signals at colonial sites are coal, foil ,small nails and sometimes deep iron...i guess because its breaking down in the ground and putting out a halo which fools the detector, have found a ton of horseshoes that way....one more tip.....sometimes you'll get an iffy or weak beep and when you pop the plug and run your detector over it it will grunt as if it is iron.....always break the plug down and rescan ...youd be surprised how many times we have done that and the signal suddenly turns good and theres a fine button to be found......the moral is ...always find what made you dig ......just don't pop a plug scan it ..and at the last minute not like what you hear and put the plug back in....finish it till you see what made you dig.....and dont forget the rise in threshold signals which are too deep to give a grunt or a beep...they should always be dug.....good luck in your hunting and dont get discouraged using these settings....it takes a bit to just use your ears but once you master it...look out