Jump to content

Whites Tdi Pro Stock Vs Whites Tdi Pro Modified

Recommended Posts

The passing of a friend unfortunately has led to me taking ownership of a modified Tdi Pro. My machine is mounted on an Anderson shaft and is factory spec. My old mate had his machine modified to smooth out the threshold and to add some sensitivity. The specifics related to the modifications are not known by me, other than that they were conducted by 'Luke'..Oz Digger.. This happened some time ago. So the modified machine is probably not a keeper, I don't want two Tdi Pro machines.. The opportunity to do a comparison cannot and should not be ignored. 

My intention is to focus on small gold performance, the threshold smoothness, the ability to use gain, basic performance and handling characteristics  under different circumstances. The machines will use the same fully charged battery pack, same coil, same targets, same test location and conditions on the same day etc. Trying to minimise external variations. I'll start with the usual useless air test. Later I'll follow up with in ground testing on the actual goldfields in mineralized soil. Test coils will be with a small coil and a large coil. Targets will be gold only. The 1 grain ingot, the half gram gold coin, a half sovereign gold coin. Some real small sub gram nuggets to see how small we can go.. There is a process involved so I'll take my time and do it right.  Any specific questions or suggestions, speak now or forever hold you peace.. I'm only doing this once. Once it sold it will be too late to revisit.. 

All the best.


  • Like 5
Link to post
Share on other sites

  • Replies 31
  • Created
  • Last Reply

Top Posters In This Topic

Top Posters In This Topic

Popular Posts

I'll do better next time, titles would be nice. Clearly first machine is a Tdi Sl, second is the modified Pro followed last by the standard Tdi Pro with Anderson carbon fibre shaft.. The modified mach

The passing of a friend unfortunately has led to me taking ownership of a modified Tdi Pro. My machine is mounted on an Anderson shaft and is factory spec. My old mate had his machine modified to smoo

The location used for this comparison between the two Pro's is German Gully near Fryerstown in Victoria. The ground is very hot, has been worked and surfaced in areas. Produced nuggets, iron stone and

Posted Images

Sorry for your loss.  I do however look forward to seeing your test results.  Thanks for taking the time to do this.

I would guess you'll keep the one of the two that performs the best in your tests so the modified machine may not be sold!

  • Like 1
Link to post
Share on other sites

phrunt, the answer is the modified unit is a goner, long term I'll keep the standard machine, regardless of the results. The reason is I know the history of the standard unit and have looked after it since near new. I can vouch for its history etc if I ever decide to sell.

Do you keep the car with service books and history, or the one with an aftermarket turbo..... 

I've been asked to do a video showing the differences in threshold, I'll show the Tdi SL, modified Pro and standard Pro. It won't be very exciting but it may be informative.. At least I used a DSLR, external Rode microphone and a decent Miller tripod.. no music, just threshold hummmmmmmmm...

  • Like 4
Link to post
Share on other sites



I'll do better next time, titles would be nice. Clearly first machine is a Tdi Sl, second is the modified Pro followed last by the standard Tdi Pro with Anderson carbon fibre shaft.. The modified machine clearly has smoother audio than the standard machine which exhibits that atypical warble.. more to come..

  • Like 6
Link to post
Share on other sites

Good video. Nice to hear those differences, at last. First time I've heard the threshold on the Big box units.


Link to post
Share on other sites

That warble in the unmodded Pro is what drove me to distraction in both my original and Pro machines. For me that particular mod was a life saver.

Karelian, I believe the second mod in the modded Pro is to increase sensitivity to small gold. That may be worth looking into during your testing. And for me if the turbo vehicle met my needs better than the stocker, the stocker would be the goner. Looking forward to your test results. Thanks for doing the testing.




  • Like 2
Link to post
Share on other sites

Tested small gold sensitivity and ability on porous gold using Coiltek Tdi 6" mono coil.  Both machines were tested on the one grain ingot, the modified unit beat the standard unit by 5mm or half a centimetre. I suspect the smoother threshold makes it easier to pick up the target response but even taking that into account it was marginal. The quartz infused and partially porous gold sample is a challenge for PI machines, from testing I know the small Coiltek Tdi coil and the Sadie will pick it up. The standard machine managed 4 cm whilst the modified Pro came in at 5 cm, marginal but still a 20% advantage. The unstable threshold works against the standard machine, I only record target depth as that which is repeatable and in my mind stands out as a target.. Threshold seems to be key here, actual sensitivity is very close, just a small fraction in favour of the modified machine. Also the ability to advance the gain or sensitivity before instability was checked. A clear advantage to the modified machine. Where the standard machine peaked at six, I got the modified unit to eight. So the threshold component transcends into a bit more gain, an advantage in detecting whispers, with a bit extra sensitivity. Tested were conducted with the same battery in both machines, same time and location etc. These were air tests to determine sensitivity and threshold only. One final air test to follow before actual ground testing in the goldfields. 



  • Like 4
Link to post
Share on other sites

Same test as above, changed the coil to the Jimmy Sierra Digger 14 x 8 mono, by Miner John. Gain was less this time, only got the standard machine to 5 and the modified machine to 7. Suspect coil size plays a part in this.

Standard Pro got 1 grain 8cm,  0.5g gold coin 31cm, Half Sovereign 42cm.

Modified Pro        1 grain 9cm, 0.5g gold coin 33cm, Half Sovereign 45cm.

Both machines with ground balance OFF, pulse at 10, conductivity on ALL.

So a pattern of behaviour is showing, the modified machine has a smoother threshold, it allows a couple points of extra gain and has a fraction more depth. This pattern seems consistent regardless of the size of target or size of coil used.. It will be a while before the next test. In ground testing on the goldfields, weather, fires and other factors will determine when.. hopefully soon.

Mike T, performance is one thing but that smoother threshold certainly makes the modified unit more pleasant to use, if using headphones to drown out the sounds of the oceans, wind etc, it can make all the difference in terms of concentration, ability to pick up on small variations in audio or whispers etc.  

The Tdi Sl has a beautiful steady threshold hum, music to my ears, with the 16v battery pack there is still a small performance deficit.. but it is a fun, super light and a well balance machine to swing.

On the standard unit I sometimes turn threshold to just silent, makes for more pleasant experience with headphones on the beach, with a small loss of performance. 




  • Like 3
Link to post
Share on other sites

I'm a bit confused.  Does the quieter threshold improve detection depth when the gains on the two Pro's are the same?  Or is it simply that the ability to increase the gain on the modded unit results in more depth after increasing the gain (and keeping the threshhold wobble the same)?

Thanks for the tests and I look forward to the continuation.


  • Like 1
Link to post
Share on other sites

Karelian, I agree completely with your comments about the smooth threshold. I am able to run both the original and Pro units wide open on gain and threshold with no warble at all. Makes for a very satisfying detecting experience.



Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
  • Similar Content

    • By Jonathan Porter
      This thread is a place were I can share and continually update pictures of any of my current gold finds, kind of like a gold diary of sorts. Sometimes I’ll include narrative other times it will be just pictures of what I found for the day. I get out detecting regularly and I use a lot of different equipment some of which is not open for discussion. This thread is NOT about equipment but about the gold I find as I find it. I will try to include pictures of the terrain so people can visualise what the areas look like where I‘m detecting. 
      I would prefer if others do not post up pictures to this thread but ALL DP members are more than welcome to comment and ask questions about detecting related subjects, especially about targeting locations and mind sets and approach. It’s OK to relate to a post and talk about your own experiences, in fact I insist on it. That’s the whole point of a gold thread, to share my daily gold finds and talk with like minded people about how much fun it is to find gold.
      The Last couple of days detecting things have been a little slow as I revisit old haunts not visited for years. I’m targeting areas associated with old gold finds looking for indications of other nearby locations that are conducive to nuggets being present. The signs I’m looking for are gravels that are exposed at the surface, especially with pieces of ironstone in the mix, then working off the edges into the soil covered zones. Clermont does not have channeled gravels that were originally associated with creeks and rivers but instead has deltas of wash that spread away from the source becoming water worn in the process, this means you can have quiet large areas of deco clays with very little gravels then hit an area the size of a kitchen with good wash that contains gold, sometimes it can be associated with a weathered down localised quartz reef which has acted as a trap for mobile gravels or it will be made up entirely of gravelly wash that has moved on-mass and delta’d out in a fan shape. The trick is to find these areas hidden amongst the tree cover and fine surface soils that hide them. Quite often you will head downslope following the gold then hit a blank of deco that goes for 30 meters then the gravels will start up again. The trick is to try and push the boundaries until either a major drainage gobbles up the contents of the slope or the ground becomes barren. The hard part is to try and decide if the surface soils are laying over gold gravel or just deco with nothing underneath. 
      Pics are of the last couple of days in two different locations.

      Day two

    • By idahogold
      Cheers" from 20f Idaho! Way to go Bill! 😃 Ig
    • By mn90403
      The police found it!
    • By oddcoiler
      Speaking of PI detectors.
      Now that Garrett has aquired  White's.
       How about a multi frequency Whites TDI ???
        98 frequencies from the Infinium.
      Added to the Whites TDI with it's incredible ground tracking and ground balance.
       That sounds interesting !
    • By bamajoe
      I have a TDI SL coming in today. I know most people want to detect for small gold. In my bad soil I want to detect silver coins that my CTX3030 can't reach. I'm a long way from the beach and probably long way from gold. That leaves coins and relics.  I've heard that larger coils tend to ignore small trash which sounds good for a coin hunter. I know that if you raise the delay that this helps but with a loss of depth. A 12" dual field and 7.5" dual field are coming with the machine.  What could I get that would be better suited for detecting coins?
    • By JohnnyRox
      Which do you think will hit deeper on wet sand?  I'd prefer a TDIBH over a DF but I'm budget limited.  
  • Create New...