DD VS Concentric, questions regarding target sounds

[hotrod53]

Having been used to using a concentric coil for 20+ years, and now using a 5 x 10 DD, I'm wondering if by going to concentric it would make the target sounds any different? When you think about it, the DD being described as a straight line signal combing the ground, kinda like a wiper, for eliminating trash, this makes perfect sense to use it. A concentric on the other hand is a signal cone penetrating down to a point, but since the cone is wider at the top, would that not put a somewhat shallow find into the signal field for a longer period of time and therefore change the target sound? Obviously not the frequency of the tone, but maybe the duration. Of course, there would be an obvious trade off when searching for a deep target, you would have a much smaller signal field the deeper you got, and therefore would make it easier to miss a good target. For coinshooting, would it really matter since most coins are in the first 4-5 inches anyway?

The reason for my question is wondering if by going concentric, will get back some of the sound recognition that I was used to with my old detector? The best part about the experiment is that I have a 9" concentric available from my brother to try, if it EVER QUITS RAINING, I will do so!

 

[Digger]

As you pointed out, the pitch of the target will be the same, regardless of whether you're using a concentric or a DD coil. The "width" of that sound will, however, be narrower on the DD due to the length of time the target is under the "sweet spot". Naturally, there are a lot of variables.......... depth of target, size of target, sweep speed etc. To sum it up, if you had a coin at a depth of 4 inches, a concentric coil will have it under the "sweet spot" for a longer period of time than a similarly sized DD coil. Again, due to the narrower detection pattern of the DD coil. What you are also likely to find is that the concentric gives a more consistent tone, since concentric coils are better discriminating coils than similar sized DD coils. If you want to use the DD for better target separation, and don't want to give up the sound recognition of your old detector, try sweeping the coil more slowly. Not only will the target remain under the "sweet spot" for a longer period of time. But you'll also benefit from much better target separation in congested areas. As to having a "trade off" on deeper targets....... I recommend overlapping concentric swaths by at least 1/2. DD coils by at least 1/3. Although some folks view a DD coil as having a sweet spot that is blade shaped, right down the middle, the DD coil detection pattern also "fades" as the eddy currents get deeper into the ground. In other words, at a depth of 7 inches, a small coin might not be detected if only passing under the front inch of a DD coil. Not a lot different than a concentric coil, when viewing the detection pattern from front to back. In fact, in moderately mineralized soil, the concentric coils will hunt deeper than a comparibly sized DD. JMHO HH Randy

 

[Snoopy36]

I have noticed subtle differences between the HF DD (5x10) and the MF DD (10.5).

The MF seemed to be consistently more reliable on depth. It's almost as if with the MF, each arrow = 2inches while with the HF one arrow = 1 inch. 'Just an observation - not evidenced by strict testing but I found myself digging much deeper targets with the MF with the same number of arrows.

Our aluminium screw caps is usually the same TID for a $1 or $2 coin. With the HF, i have found it slightly easier to differentiate the sound of screwcaps from coin sound. Not so with the MF coil. Often a screw cap will sound sweet and solid just as a $1 or $2 coin.