Threshold

[Guest]

I am still unclear what threshold does on this machine, and what it actually changes in terms of signal quality and machine response to target. It does not seem to act in the way I understand the term so I am unsure how to actually use it to make the MDT do what I want it to do. That seems true in some of the other controls too, everything is a little different, but they are easier to see the result of in real time. Can anyone make sense of this for me in real terms?

[JCR]

I understand where you are coming from. It is a different animal for sure & the manual is not detailed enough for me. What I have done is a lot of testing, one thing at a time, on more difficult targets. I still do not feel I have a full understanding of how it all inter-relates & inter-acts as a whole platform.

Threshold seems to have a greater effect on weaker target response. This includes fringe depth & very small targets. It also has a big effect when dealing with EMI or ground that has a lot of natural iron/rust, especially if it's wet.

Sensitivity seems to have more effect on how strong a signal sounds once it gets over the Threshold. It is not as dramatic an adjustment. I use Sensitivity to adjust for how "Hot" the ground is by listening to the ground response.

It is really all a balancing act, just like any other detector. I try to keep the Threshold fairly high(-2, -1) and Sensitivity to run smooth. It is a surprisingly deep machine even at 2 sensitivity if you are paying attention.

@Danceror @dewcon4414are the ones to give their observations on Saltwater hunting. Mine is all inland red dirt sites.         Tom Dankowski's forum has lots of info also.

[Guest]

27 minutes ago, JCR said:

Sensitivity seems to have more effect on how strong a signal sounds once it gets over the Threshold.

JCR,

Thanks for this reply. Here you perfectly state how threshold is usually understood. It is a sort of minimum requirement for some given action, in this case a signal. It does not quite act like that, and seems to have a complex interaction at the least that I struggle to truly understand as I try various combinations of settings looking for the holy grail. 

And you are absolutely right about the Dankowski forum, there is a lot there and it is very helpful indeed. It has been my reading there that prompts starting this thread. Tom D states more than once that he prefers to run threshold as close to zero as he can. Yet, I have best luck running -9, and that with fairly low sensitivity. 

I played with turning it up on all kinds of combinations yesterday, and fail to understand  what the advantage of either is even though I have somehow developed a preference.

[Guest]

40 minutes ago, JCR said:

Threshold seems to have a greater effect on weaker target response. This includes fringe depth & very small targets. It also has a big effect when dealing with EMI or ground that has a lot of natural iron/rust, especially if it's wet.

I am a blockhead. This paragraph of yours may in fact be why my preference is what it is, and that because how I hunt is less common. I do in fact make every effort to weaken weak target responses because I am hunting recent drops that are found in the upper part of the soil profile.

[JCR]

Geezer,   It sounds like you have the right idea. Set the detector up to hunt according to your goals. That is what I try to do always with any detector. Targets, conditions, expectations,,,,,,,,. It is great that the Tarsacci really is a such versatile machine for tough conditions. There is just something special about it.

[Guest]

1 hour ago, JCR said:

Geezer,   It sounds like you have the right idea. Set the detector up to hunt according to your goals. That is what I try to do always with any detector. Targets, conditions, expectations,,,,,,,,. It is great that the Tarsacci really is a such versatile machine for tough conditions. There is just something special about it.

Exactly. You have it exactly. Thank you so much for your help. I see what I was doing wrong.

[dewcon4414]

9 hours ago, Geezer said:

I am still unclear what threshold does on this machine, and what it actually changes in terms of signal quality and machine response to target. It does not seem to act in the way I understand the term so I am unsure how to actually use it to make the MDT do what I want it to do. That seems true in some of the other controls too, everything is a little different, but they are easier to see the result of in real time. Can anyone make sense of this for me in real terms?

To me it’s gain.   Reduce it and you filter out weak targets.  It seems to affect modulation much like gain does on an explorer.   I believe most think we just have two sensitivities.

[Guest]

22 minutes ago, dewcon4414 said:

To me it’s gain.   Reduce it and you filter out weak targets.  It seems to affect modulation much like gain does on an explorer.   I believe most think we just have two sensitivities.

This seems right to me, and curiously little of it is required. The threshold actually seems like a coarse knob for the sens sometimes. Today I was playing with the settings on a site with a lot of EMI. I set thresh at -9, sens 2, and even set freq at 6.4 kHz, a thing I seldom do but it helped with the EMI.

Using those settings, one of the rings I found today had to be the tiniest engagement ring with the finest wire loop and smallest diamond chip ever made. I think they took that diamond off a saw blade. I hope that was a children's ring for the sake of whoever received it, but it was sized for a woman so who knows. That thing had so little gold it was all but invisible in plain sight, I have never seen a ring that delicate (cheap) before.

Here is the curious part. It rang perfectly clear with that perfect tone that only a gold ring makes. (besides pull tabs) Of course it is ring shaped which helps, but given how thin and insubstantial it is I would have expected to lose it with the low frequency and low power settings. Rang perfectly clear just like any other.

My girls will not be fighting over this one, but it shows the power of Tarsacci on a good target even when not set to be optimal for that target, and on a target without much target there in the first place.

[JCR]

As far as EMI mitigation; Black Sand ON is a good filter for it, though it will reduce target sensitivity also, Works well on ground chatter too.    So that's really 3 controls to play with to achieve your hunting conditions/goals.

[Guest]

9 hours ago, JCR said:

As far as EMI mitigation; Black Sand ON is a good filter for it, though it will reduce target sensitivity also, Works well on ground chatter too.    So that's really 3 controls to play with to achieve your hunting conditions/goals.

You are right about that one too. BS is always on for me, and salt balance as well. The controls are what really make this a great detector for me. I am doing a lot of frequency hopping at the moment too, which makes a lot of difference, but not always in a predictable way.