Coil Question

[RounderRick]

I'm a little curious about the coils for the at pro I have the stock coil plus the 6.5 x 9 and I'm wondering which would be deeper in my area.
I used the 6.5 x 9 when I first got the detector to get use to it because I have always used a concentric coil except for a small shooter coil so I figured it would make it easier while learning the detector I could pp with a coil I was use too.
I ran the sens lower at this time also so I wasn't expecting anything real deep. After I learned it I have been using the stock coil and finally got my pp with it down pat.
From what I gather if both coils was the same the dd would be deeper in high mineral ground and the concentric would go deeper in regular ground so what I'm wondering is with the stock coil being larger would that still make it go deeper then the concentric due to it being smaller in non high mineral ground or should I be using the concentric?
Thought about air testing but figure without the ground I still wouldn't know anything so thought I'd see if anyone might know I already see the old coins around here is deep so I want to use the one I'll get the best depth with.

Thanks
Ricky

 

[sasquache]

I believe due too the foot print of the stock 8.5 X11 and being a double d coil its ability too handle mineralized ground is deeper than say a 6.5 X 9 concentric.But the smaller coils handle trashy and hard too reach areas better. In my opinion i would stick with the standard 8.5 X 11 DD sent with your AT-PRO becouse i use mine in every situation but trashy area's i just go slower and still retain maximum depth the only way i would use a smaller coil is in vary small areas around rocks ect but right now i have no areas for its use. Hope this helps. SAS

 

[Monte]

I'm a little curious about the coils for the at pro I have the stock coil plus the 6.5 x 9 and I'm wondering which would be deeper in my area.

"Depth" is an all too often discussed term and the answer is usually NOT something that others can give you. There are too many variables involved in serious detecting to really put a finger on just how to achieve "depth", but I'll share my thoughts. They are only based on ample experience as I've been seriously involved in this great sport for a long time and I'm in my 47th year of detecting.

First, are you asking about raw depth that's based mainly on hearing an audio response and desired by serious Relic Hunters and Avid Detectorists, or are you asking about proper Target ID depth, or something close to it, that is sought by many Typical Coin Hunters?

Second, it can depend upon your detector settings, especially how low the Discrimination is set, how high the Sensitivity is set, if there is a proper Ground balance, and with the AT Pro it really matters if you're using the STD (Standard or 'saturated' audio function) or PRO ( Proportional Audio also known as 'modulated') Audio choices. It might also be different if you're hunting in a true Threshold-based All Metal mode (something the AT Pro doesn't have so no concern here) rather than a motion Discriminate mode..

Third, we have to factor in the 'human error' that is based on the operator's control to produce a proper sweep speed and coil-to-ground relationship because there are times when a too-fast sweep speed might really hamper performance ... especially depth or just target recognition.

Fourth, we must also look at the uncontrollable challenge and that includes two things. One is the target's size, shape, position, and metal alloy make-up, and the second consideration is the type of ground you are hunting. The amount of mineralization, and I am especially referring to ferrous or magnetic ground mixture, as well as the ground condition. It could be porous or loamy soil, fine sand or dirt, a mix of small pea gravel, a plowed condition that might have a very uneven surface and possibly some dirt clods, or even have the presence of rocks of various size and make-up.

From what I gather if both coils was the same the dd would be deeper in high mineral ground and the concentric would go deeper in regular ground so what I'm wondering is with the stock coil being larger would that still make it go deeper then the concentric due to it being smaller in non high mineral ground or should I be using the concentric?

Well, size isn't a factor because the two coils are of different size and shape as well as different internal winding design.

There has been, and is, a lot of talk about using a DD coil to get better depth in 'mineralized ground" and perhaps in some applications that might be true. I have used makes and models from various manufacturers when I have had same-size and shape search coils that were concentric and Double-D. Some have been very close in size to qualify for comparison. I've compared them, side-by-side, in urban grassy parks, black sand volleyball courts, rocky-mixed renovation work such as torn up sidewalk and street repair, working plowed fields, and in gold nugget hunting applications.

I will say that there are some DD coils that I like, sometimes, and for certain applications. Sadly, there are some makes on the market that have ONLY a DD coil available, or ONLY a concentric coil available so you can't enjoy a difference. I always try to match the detector and search coil for the types of sites i plan to hunt.

My bias is that I am a very strong fan of concentric search coils and most readers or those who attend my seminars know that. I state it here so that it is clear, but I also stated that I do like some DD coils so I am not totally single-minded on the topic. I will say the most of the gold nuggets I have found when hunting in Oregon, Arizona or California gold producing sites for a quarter century have come when using a detector equipped with a concentric search coil. Most printing suggests using a DD and associates it with typical bad ground in those sites. That hasn't been the results I have enjoyed.

I also favor a concentric coil design because they are usually much better at discrimination, especially iron-based targets. I like the easier pinpointing and ability to size and shape a target with a concentric coil. I prefer smaller-than-stock coils the most because I usually hunt in iron infested or just trashy sites, and side-by-side the concentrics have performed better overall for me.

Finally, since you asked about 'depth,' I have also had better depth of detection using a good concentric coil compared with a similar-sized Double-D coil.

Thought about air testing but figure without the ground I still wouldn't know anything so thought I'd see if anyone might know I already see the old coins around here is deep so I want to use the one I'll get the best depth with.

How deep are the older coins found in your area, and have you considered what has caused them to be 'deep' in the first place? I find a lot of old coins, but most of the time it is clearly based on site selection.

As an example, I have one favorite ghost town that I have been hunting since May 4th, 1969 and I feel rather comfortable in telling you that nobody has spent as many visits there or as much time detecting as I have. I have been there twice this year and it is in Northern Utah and I live in NW Oregon. When this far away I try to make 2-5 trips a year, and some of those 'trips' actually include 2-4 days on-site. When I lived closer in Utah, the two routes from home to the old town site (nothing standing since about 1952 or 1953) were between 96-100 miles for the shorter route that included desert dirt driving, and 1006-110 miles if I stuck to the highway for most of the travel and had a nearby (30 minutes) gas and grub stop.

Those are one-way mileage figures and, for example, between May 1991 and May 1992 I made 36 trips there. That's an 'average' of one trip every 10 days, and a few of those were multi-night camp-outs. Most coins have come from surface to 3"-4" but the dense iron trash makes it difficult to hunt up those targets. And when I say 'surface,' I mean just that. I have hear a detector beep and glanced down to spot a circular disc on the surface, and there have been many times that I simply spotted a coin or token before the coil was swept over it.

My oldest coin from there? An 1836 Capped Bust half-dime from about 6". All of the Seated Liberty half-dimes have been found on the surface to maybe 3

 

[threefingerdave]

Monte,
That was a VERY good post!
Thank you very much
Sincerely
Dave

 

[RounderRick]

Thanks l lot monte I've always appreciated your opinions and the time you take to explain things to us with less knowledge. As I've said I've always used the concentric coils with everything I've had because that's what's always came on my detectors.
Since I had to come off the road as a truck driver due to health reasons and I started this hobby seems all the jobs here is low pay unless you got some kind of degree or years experience which I don't so can't afford to go all out that's why when I want a certain detector I have to sale the one I have to be able to get it but I have found a keeper with the at pro it's got everything I want and need in a detector.
Now I did get a deal on a shooter coil that was a dd when I had my mxt and that the only dd I ever used so that's why I was asking I never used a large one like the one on the pro and I do like it but I am better at pp with the concentric I just wish it was the 12" instead of the 9" I know I'd be using it but that's not gonna happen no time soon I been saving for a pro pointer seems like forever and that's what I need worse than a new coil right now.
I do thank you and I may just put the 6.5 x 9 back on now that I'm more use to the detector and see how it goes for awhile and as for the ground here it's kinda weird with my other units the auto gb would run between 50 and 60 but with the at pro it balances out between 70 & 80 so I don't what's up with that but I've seen several ask that question so I quess it's just the nature of the beast to gb higher than others but it don't seem to hurt the performance.
I just recently found my first silver with it at 8" deep here in my yard that I've pounded many, many times and the tone was loud and clear with a good vdi reading which was a surprize to me plus awhile later I found a button it was the first one of them I've found in my yard too.
Another strange thing is I can run the at pro in my yard with a higher sens than I could with any of the others most of the time at default but sometimes I can run it full I don't know if humidity or something with the weather causes the change or what but that's the truth but it just so happens the day I found my silver I was able to run at full sens.

Take care all and happy hunting.