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Tdi vs Tdi Pro?
Posted by: tvanwho
Date: March 28, 2011 02:14AM
Is the Tdi Pro any better than my stock TDi? What are the differences? Will Whites upgrade my Tdi for a fee? How does that Digger 8 x 14 coil compare to the stock coil for deeper gold in hot dirt like in central Arizona?

-Tom V.

Re: Tdi vs Tdi Pro?
Posted by: ColoradoGoldMan
Date: March 28, 2011 03:47PM
Is the Tdi Pro any better than my stock TDi? What are the differences? Will Whites upgrade my Tdi for a fee? How does that Digger 8 x 14 coil compare to the stock coil for deeper gold in hot dirt like in central Arizona?

-Tom V.

Hi Tom.
The TDI Pro has few more adj on it than the TDI I has a course GB and a fine GB for tricky ground. I also has a volume for the threshold so it can be set to what ever volume you prefer, It has more aggressive filtering, which may sharpen up target response on some finds. That about covers the differences. No Whites will not up grade the TDI to TDI Pro. The Digger coil is a true mono, it will help a little on small gold, over the 12" DF mono from the factory. Whites also makes a 12" true mono that they send out with the TDI Pro OZ version. Both the TDI's will use any of the Minelab coils as well as the after market coils for Minelab PIs. You don't say where your hunting areas are but I have never found any soil that my TDI can't handle here in the USA. Unless you are headed down to Australia there is no need to upgrade to the Pro. There are other people making coils and accessories here in the USA as well. If your looking to do some nugget shooting in AZ or any place in the Southwest the TDI will do a great job. It will handle any thing there all you need to do is get the coil over the gold.
Keeper Swinging

"I predict future happiness for Americans if they can prevent the
government from wasting the labors of the people under the
pretense of taking care of them".
Thomas Jefferson
GPX 4000, Whites TDI
Falcon, CO.

Re: Tdi vs Tdi Pro?
Posted by: tvanwho
Date: March 28, 2011 04:16PM
Thanks CH. I keep falling into this trap where anytime a detector I own , the mfgr comes out with a supposedly upgraded model, I get the urge to get rid of mine and upgrade. Of course, I usually end up with an expensive loss and spending more than can be justified. Do detector manufacturers do this on purpose just to keep sales up? I can't afford to keep doing this anymore?


Re: Tdi vs Tdi Pro?
Posted by: Reg
Date: March 29, 2011 10:25AM

In the case of the TDI pro, the mods were the result of testing done by Eric Foster by going to OZ to evaluate the TDI. As a result of his trip, he made recommendations to the TDI to make it work as well as it could in the bad ground found in OZ. Once Eric completed his evaluation and testing, he made his recommendations to Whites and Whites implemented those changes to assure the TDI would work as well as possible in Australia. This evaluation was performed since many people in OZ were asking for the TDI and Whites didn't want to send a detector until they felt is was ready.

Thus, the Pro was developed to incorporate certain mods primarily aimed at tackling the really bad ground found in Australia. One change that wasn't aimed at the bad ground was the minor filter change designed to make the Pro a little more sensitive to small gold.

The primary coil on the Pro sent to OZ is a true mono and not a dual field. The reason is, the DF doesn't ground balance quite as well as a plain mono design. In OZ, it makes a difference that is noticeable. Here I have not found the DF to display any weaknesses to speak of. In fact, the DF has advantages because it provides enhanced signals to small gold not found on a regular mono without having to use a DD coil.

BTW, a DD coil will work just fine on a TDI or the Pro even though there appears to be some information to the contrary. Since the TDI design is unique, it can handle ground extremely well using a mono even in places that other PI's may require a DD. So, the DD has never been recommended like it is for other PI's.

Now, with that said, usually a DD will provide better or stronger signals on very small gold but will lose a little depth when compared to a mono on larger gold. The key to using a DD is to sweep slowly and smoothly to take advantage of any depth advantage on the small stuff. The biggest mistake most nugget hunters make is to sweep the TDI too fast. This becomes even more important when using a DD.

Getting back to your wondering about why the Pro was developed, I hope this answers your question as to why the Pro came about. It wasn't something the manufacturer did as a simple upgrade, but was developed because of a demand in Australia and White's desire to meet that demand with the best they could at the time..


Re: Tdi vs Tdi Pro?
Posted by: tvanwho
Date: March 29, 2011 11:42AM
Can you elaborate more on sweep speed Reg? Feet per second or how do you describe this to people? What has coil speed got to do with detecting objects anyway? I never did understand this ? Them old Teknetics machines from the 80s had people whipping the coils around, why?


Re: Tdi vs Tdi Pro?
Posted by: Reg
Date: March 29, 2011 01:37PM

There is no way to truly explain sweep speed or what would be the best sweep rate. Instead, it is something the person running the detector has to find out by simply running a few tests.

The key is to use a small target like maybe a 3 to 5 grain nugget. If that isn't available, then a similar size piece of brass or lead can be used. Now, the test should include simply placing the test object on the ground and later by burying it to a distance where the signal is weak at best.

Then it is a matter of passing over the buried object at different sweep rates and listening to the signal strength. Without trying to explain the actual speed, I will explain what one guy found out. Now, I had a guy try this test in AZ a couple of years back and he was amazed with the fact that if he swept slow enough he could add a couple of inches of depth to his small test nugget. More importantly, the signal from the nugget became loudest at the ideal speed, which was far slower than he was accustomed to using. So, slowing down was presenting a problem for him.

So, why does sweep speed have an effect? Simple, the design of a metal detector is complex and contains several filters performing specific functions. Some filters are there to help with ground signals, others are to reduce noise and others simply to change signals from DC to AC to eliminate voltage offsets. Regardless of why, each filter will have an effect on the signal from any object. Filters used to reduce noise will also reduce target signals, especially if the coil is swept too fast. Normally, on a PI, this noise problem is far worse than that found on a VLF, so more filtering is used. Normally noise signals are higher frequency signals but are quite strong, so filters are designed to reduce this noise as much as possible. Unfortunately, the same filters will also reduce good signals if the coil moves too fast simply because of how the target signal responds. The faster a coil is moved, the higher the frequency of the signal from the target. This becomes even more important on signals when using a DD coil because most target responses are really quite brief but sharp to begin with. Go too fast and the signal comes and goes before it gets a chance to fully develop.

I personally can't tell one what to do or what speed is best, because there is no way to explain it correctly. So it is up to the owner to find that "right sweep speed" themselves. Those who elect to take time to find out what speed works best will ultimately be the one who is the "luckiest" and will find more good targets. Unfortunately, most people elect to do it their way and not take the time to find out for sure. So, they usually get upset when things don't work out as planned or expected.


Thank you :clapping: Again.
Posted by: ivanll
Date: March 29, 2011 05:40PM
Some explanations deserve to be printed and added to the Instruction Manual.

Another one to Pin at the top !!!!!!!!!


Thank you :clapping:
Posted by: ivanll
Date: March 29, 2011 05:47PM
Pin it to the top please, or make and add it to a page with "How To Tips".


Re: Thank you :clapping: Again.
Posted by: Reg
Date: March 30, 2011 12:30PM
One thing I forgot to mention is this filter response or effect is target size dependent. By this I mean, one can't use coins and expect the filtering to act the same as it does for small targets such as a small few grain nugget. Bigger targets are just that, bigger. As such, the signal will be there a little longer and, of course, larger. Small targets such as a small nugget are brief responses in comparison and as such are much more susceptible to the filtering actions.

One more problem when trying to find the ideal sweep speed and that is noise. Trying to determine the ideal sweep speed in a noisy environment is also self defeating simply because noise impacts all targets but the impact is more significant on small or very deep targets. To minimize this problem, one should try to find a quiet location rather than simply make a few tests at home where noise generally can be a problem.

To better understand how noise can influence this test, simply test a target using an air test with the GB off and then repeat the test with the GB on and set to 9 or so. In most cases, there will be a noticeable difference in detection depth, especially on small objects. As a general rule, any difference in target signal is the result of noise and not the interaction that occurs when the GB is adjusted. This, again, is target size dependent. In extreme cases, a very small nugget my just be detected with the GB off but will not have any noticeable response with the GB on.


Lets Talk About Pulse Delay Settings For Relic Hunting
Posted by: bigchuckinva
Date: March 30, 2011 08:05PM
I have had my TDI Pro few few weeks so far I have been impressed with depth both in Bad Ground and even Good Soil. Just last week there was Relic Hunt called BMW which was held in Central Va. which has more like "Hotter Bad Ground in USA. The TDI Pro was very easy to balance and course adjustment was only thing that was need few times a day by the worse soil. The standard TDI work fine but seemed to need more adjustment then TDI Pro. The Pro on Avg. I could run higher just little higher gain settings then base TDI and seemed be little more stable. I talked lots TDI Relic hunters whom most common talked was about was Pulse Delay setting. The White info says at 10s but most Hunters seem set in middle at 15s. At 10s in hot ground it hard ground balance and seems harder it not pick nails heads other iron from god targets . At mid ranged at 15s I had no issues ground balance, and knock out nails better and tell by tones in All and Idug many super deep buttons over 16 inches plus. Some Relic Hunters say they set at max 25s . So whats folks options ref setting Pulse setting Relic Hunters???? If you hunt real hot Soil the extra money for TDI model will be worth extra money > The added Volume is great future and TDI model also look more Professorial looking in lay out the setting. Chuck

I have the base model TDI and always hunt the super hot soil of Culpeper.
Posted by: Charlatan Digger
Date: April 08, 2011 07:50AM
I have absolutely no problem in turning my gain all the way up. My machine is always stable as can be while the knob is pegged as far as it can go. Found this an 18+ deep!!!

Re: Tdi vs Tdi Pro?
Posted by: Nuke em
Date: May 17, 2011 11:58AM
I am trying to get the money together for a TDI but have been wondering if i should buy the pro, if i can get the pro i will but next week i am getting one which ever it is.
Then i will get a Razorback coil and control box cover , i think that will complete my arsenal for the next few years unless i win the lotto LOL
Thanks for the info here.

Re: Tdi vs Tdi Pro?
Posted by: Downdeep
Date: May 17, 2011 04:28PM
I have volume controlled headphones, so that is not an issue. And, from what I've read in certain circumstances one may want to run it either slightly above or below ground balance. In this case, I don't think the fine balance control would be worth much. My opinion for what its worth as most of my knowledge by far of the TDI is from a LOT of reading. oh, and a whopping 3hrs in the field with it. lol :detecting:

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