Testing The New 8.5 x 11 DD Coil On The Ace 250

[Tarot]

Hi Everyone

Here is my report and initial tests of the new Garrett 8.5” x 11” DD PROformance search coil, fitted to the Garrett Ace 250. Most 250 owners will be using the standard coil, and much of this report is a comparison between that and the new DD coil.

The build quality is very good, and the new coil seems to be a strong design. It is a good fit onto the lower stem, and there is no drooping or need for any coil support. When first fitted it looks enormous, compared with the standard coil. But the biggest surprise is the weight, or to be more correct the lack of weight.

6.5” x 9” (No Coil Cover) = 454gms or 16oz

6.5” x 9” (With Coil Cover) = 515gms or 18.2oz

8.5” x 11” (No Coil Cover) = 468gms or 16.05oz

So for all of its extra size, the new coil come in just a fraction heavier than the standard coil.

Below are some pictures of both coils side by side.





Now onto some air testing of the two coils. I know many of you will not agree with tests done in this way, but they have been done to provide a comparison.

Below are some pictures of the targets used in the test. These include UK and US coins, and some jewelry and junk items.









I tried to keep the test between the two coils identical, and as fair as possible. The tests were done on a wooden surface, away from any metals or electrical interference. I ran the targets past the coils at a normal sweep speed, and not whipping them to achieve better results. I only recorded good two way signals. The 250 was set in the All Metal mode, and each coil was tested at sensitivity settings of 4 and 6. It should be noted that the DD coil suffers more from electrical interference than the standard coil. But I have found this to be a characteristic of all the DD coils I have used in the past.

Below is a table showing the test results.



As you can see from the results, the new DD coil performed very well. At equal sensitivity setting it out performed the standard coil on almost every target. But by design the DD coil should perform better in badly mineralized ground and on salt beaches. So in theory on a wet salt beach where the standard coil could be run at a sensitivity of 4, the DD coil may run at sensitivity 6. If this was the case, the depth improvement could be as much as 30%.

Much of this is just theory, and I hope to get out to the beach very soon, and put it to the test. At least the comparison chart gives you a good example of how the new coil performs, under air test conditions.

I hope some of this information will help other 250 users considering purchasing the new coil.

Kind Regards Tarot.

[BountyHunter]

That post is a keeper for all those owners of the Ace250 pondering the purchase of this bigger DD coil.

Although I am not an owner of such a machine I enjoyed your findings and archived them in my Ace250 folder ;-)

[FL-Hunter]

Just an FYI: Air tests are much different than soil tests. They do not even compare. I have tested air vs. soil tests with my ACE 250 and the results are much different.

The larger coil detects deeper no doubt, but the slice of the ground it is detecting in, will be much narrower to get deeper. There is a trade off when using that larger coil. Do you want to go deeper but narrower or do you want a more wide detection area and maybe a bit shallower?

Call Garrett, they can explain it better if you want all the tech specifics. I found this information while doing research into the new ACE 350 model.

HH

[Tarot]

Originally Posted by FL-Hunter

Just an FYI: Air tests are much different than soil tests. They do not even compare. I have tested air vs. soil tests with my ACE 250 and the results are much different.

The larger coil detects deeper no doubt, but the slice of the ground it is detecting in, will be much narrower to get deeper. There is a trade off when using that larger coil. Do you want to go deeper but narrower or do you want a more wide detection area and maybe a bit shallower?

Call Garrett, they can explain it better if you want all the tech specifics. I found this information while doing research into the new ACE 350 model.

HH

Hi FL-Hunter

Thanks for your reply, on my testing of the new coil. I did say "I know many of you will not agree with tests done in this way, but they have been done to provide a comparison." I did not intend for this to be a comparison with in soil results, but a comparison between the two coils in a controlled environment.

As for the narrower field of detection, I consider this to be an advantage. The narrow field provides better target separation, compared to a concentric coil.

Because you are swinging side to side, it has no effect on the amount of ground covered. Also the new DD coil being 2" longer, will actually cover more ground per swing.

The only negative thing that I could find with the DD coil, is that it suffered more from electrical interference.

Just my personal observation, from using this and many other DD coils in the past.

Regards Tarot (Bob)

[Tarot]

Coil Test Update

Hi Everyone

When I wrote the original report, I did not have the coil cover for the new DD coil. The covers have just become available, and I can now update the weight comparison (With a surprising result !!).



Firstly all of the weights shown in grams are very accurate, but some of the conversions to ounces have been rounded up or down. In the original report the weight of the 8.5” x 11” coil was wrongly converted, and should have read 16.5 oz.

So to clarify the weight comparison, I have relisted the weights below together with the new coil cover data.

6.5” x 9” Coil Cover = 61gms or 2.2oz

8.5” x 11” Coil Cover = 46gms or 1.6oz

As you can see, the 8.5” x 11” coil cover is much lighter than the 6.5” x 9” coil cover. This has been achieved by having a more open design, and being a much thinner profile.



6.5” x 9” (No Coil Cover) = 454gms or 16oz

6.5” x 9” (With Coil Cover) = 515gms or 18.2oz

8.5” x 11” (No Coil Cover) = 468gms or 16.5oz

8.5” x 11” (With Coil Cover) = 514gms or 18.2oz

So the 8.5” x 11” coil + cover is actually 1gm lighter than the 6.5” x 9” coil + cover. (Amazing considering its much larger size)



I have still not been able to get out detecting with the new coil, but hope to get out after the holidays. I will update this thread with the results.


Kind Regards Tarot

[BountyHunter]

Again, much thanks Tarot.

You give details, updates and nice photos to accompany your posts.

standing by for any of your updates

[outwardjourney]

When you get a chance to use the new coil, tell me where your pinpoint marker is on it. I am having trouble locating the right area to dig after pinpointing.