Threshold setting on the SDC.

[Hotrob]

Could someone who has experience with the SDC please give me some advise. I was told on my Minelab training day when I bought my SDC to run the threshold just above the lower settings.
I have done this & found a lot of lead shot so I know this works but the other day while out swinging I met a fellow prospector & after a bit of chat he asked why I was running the threshold so high. I explained that I was a total newbie & that was what I had been told to run it at.
He told me that he also used an SDC & was quite experienced with it. He said to turn the threshold right down & run it silently (then when you hear a noise... you have a target). I tried it & imediately found more lead shot so I know his theory works & it was a lot easier to use as there was very little noise apart from the targets.
So what setting should I run & why????? Because I found small shot with the SDC running silently I tend to lean towards his theory but is there something I'm not aware of that could cause me to walk over the elusive GOOD stuff.
Any advise please.
Rob.

 

[LC76]

I run mine on the fourth light and sensitivity on green (2) sometimes I go to 3.

Any higher setting in mineralised grounds becomes to noisy and you miss a lot of targets.

 

[LC76]

I used to run on 4 and would get about 5 nuggets each day.
Now on 2-3 I get no less than 10 in a good area.

 

[Syndyne]

Hi Rob,

Just to clarify, are you running a booster/speaker setup on the SDC?

As long as you're threshold is smooth and well balanced/auto-tuned against EMI, hot ground etc. and you're finding that pesky small lead shot then all should be fine. I don't run a speaker setup on my SDC as I'm used to the headphones now so maybe the other guys might offer some more advice in those regards?

Outside noise influences such as wind can effect a speaker at lower volumes. Also you don't want to give yourself industrial deafness having it too loud. Just a nice comfortable volume should suffice. If you notice you can still hear the threshold whistle in your ears when you go to sleep then it's probably running too loudly.

Throw a few targets in the ground, or check ones you're finding in the field in different settings/volumes and see how you go. We did our share of trial and error in the beginning too. Even though it's a fairly simple machine, it's still a slight adjustment for every area you go, patches you work and different daily influences, as much as any detector really.

Some of the gold I've found with the SDC, in a few rare cases nuggets up to half a gram, being either surface dwellers or deeper ones down to the eight inch range were barely heard through the general threshold warble (using setting 2 and well balanced), so it's only that there was enough of a repeating signal through the contributing factors such as EMI for me to recognise there was a target to dig, or just pick up. Once you scrape that first inch or so off it's usually clear there's a target present if it's deeper and don't kick the surface dirt away too hard as you can lose a small sun baker very easily!

Cheers,
Shauno.

 

[Heatho]

I run my threshold on the third led, seems about the right place for it for me, I've tried the silent approach and believe you will miss smaller targets at depth using it this way, as Shauno said your listening for the tiniest variations in threshold sometimes and with it turned right down there is no variation to hear, it will either sound or it won't and that's not the way minelab gold detectors are meant to run. If you use a silent threshold you are missing a lot of info about what's happening under your coil.

 

[Bacchus]

Gday Hotrob

Good question and thanks for posting , I never did any training but have about 150 hours up on my SDC so can only let you know my own personal experiences. The best advice I can give is take a couple of test pieces with you and spend a couple of minutes when on site trying at various settings before getting going.I tend to run mine Hot and try and listen through the warble , takes a while to get used to it but I have no doubt that one nugget I found at 7 inches would not have been heard if I had not had the machine set up in this way , the threshold pull was not loud but different , this made me do a second sweep which confirmed it as repeatable thus worth a dig. I also use headphones so can not comment on the speaker / booster set up.

Good luck with it

Cheers

 

[Wally69]

Good question, what you are doing by running it silent is picking up a definite spike response from the target. I gave the silent setup a good test and have found it works well on most shallow targets so long as sensitivity setting is at or below 3. The only downside is you will probably miss those targets that give a very flat increase in threshold as they will be masked by the silent setting.

I agree with Shauno, the deeper targets I have found tended to be so feint that they would have been masked in silent mode, a just audible and very stable threshold is what I am chasing when I set it up now.

I usually run threshold on the lowest setting I can, second or third light, with sensitivity on 3 or 4. I find 5 to be unstable for long term use but it definitely gives a better spike response from small targets. Knowing this, I have picked up additional micro-nuggets off a patch by cranking the sensitivity and threshold up and also by running silent.

I think there is a distinct advantage in using the variability in the SDCs settings on a patch of small gold. Running the settings at different extremes has certainly produced more gold for me.

It is certainly more pleasurable to run it silent but I am sure I could miss something deep when I do, so as a rule, I don't anymore.

 

[mbasko]

I have the threshold on 3 LED's as I find it works for me & is smooth but still gives enough feedback for the feint signals. I run a booster though & use the volume on it to adjust from there. Have been running the sensitivity at 4 & drop back to 3 if needed. Using the booster & having volume control I find you can run a bit higher.
Went for a quick run today & it was very windy. Some big gusts at times so thought it would be a good day to test the SDC & myself. I left it on sensitivity 4 all day & just used the booster volume to adjust for conditions. This spot is fairly highly mineralised. I got 6-8 subgrammers (haven't done a tally yet :8 ) & 2 speccis for the day.
One thing I found today staying on sensitivity 4 was that I picked up about 3 hotrocks today. Previously running 2 or 3 I hadn't picked up any at this spot (or anywhere else). It also seemed to get a few more "yips" with the wind gusts & near powerlines I had to retune a couple of times whereas once usually does it. If you can put up with that with the higher sensitivity I reckon it does brighten the feint ones up - using a booster anyway? I have tested signals (in situ) & 4 is a little brighter through the booster anyways.
In all honesty if I wasn't test running in the higher sensitivity I would have went back down to 3 - makes me wonder if I would have found a couple of the smaller ones if I had of, especially with the wind? Should really have put headphones on too

 

[rc62burke]

I believe you could miss targets also with the silent approach, keep it at a low hum (I don't know where I run mine, but it's a low hum) this is the only way to hear a blank in the threshold that would indicate a feint target!!!
I like to run mine hot 5 to me is optimum, but I am used to noise as I use an SD2200 with mono's, I can pick up very feint targets with the SDC.
Lee

 

[isolation]

Good info here!

I used to run my threshold quite high, over halfway, but since dropping it down a couple of notches, I find the falsing sounds that were quite regular, seem to have reduced. I am also able to run the sensitivity higher, on 3 now. Based on what I am reading here, I will try dropping it further, and lifting the sensitivity to 4-5.

 

[mbasko]

Was 9 bits & 2 speccis that I got the other day running threshold 3 sensitivity 4 through the booster & speaker on a windy day. Still picked up the small ones fairly easily even with the wind noise. Had the booster volume up an extra notch to compensate but not much more than normal.

 

[Bacchus]

https://www.prospectingaustralia.com/forum/img/member-images/4485/1426791185_14266699488301.jpg
Was 9 bits & 2 speccis that I got the other day running threshold 3 sensitivity 4 through the booster & speaker on a windy day. Still picked up the small ones fairly easily even with the wind noise. Had the booster volume up an extra notch to compensate but not much more than normal.

Great Job Mbasko , keep on giving mate , it keeps people like me going and dreaming of better finds to come

Cheers

 

[Hotrob]

Ok.... I've got a lot of very helpfull info there guys. Thank you to all who bothered to answer.
Firstly I don't run a booster & wasn't using the supplied headphones. I was just relying on my ears picking up signals through the SDC speaker but after my chat with the old mate mentioned he also suggested I should use the headphones or ear plugs......... so I did as he suggested & ran my SDC on silent with the headphones on.
Now for the confession...... I was a total newbie & a gold virgin until the session I have just relayed (still a newbie). I stayed at a spot near Moliagul for five hard days (8am 'til 6pm most days) & found 12 small pieces of gold (thank god there were no wittnesses to my first piece of gold..... I wasn't sure if it was the real thing until I spat on it ...WOW .... what a beautiful colour) anyway I also dug 222 other targets during the five days.... mainly shot, hob nails, ring pulls, .22 cases, an old threepence, a shoe buckle, a five cent piece & three pieces of quartz/rock that set the SDC off.
I didn't mention this in the original post as I thought a virgin would get more advice.
Now had I known that I would find twelve pieces (total weight of 0.9 of a gram) I would not have beleived I could be that lucky on my first true try.
But now I wonder if I had this advice you guys have offered how much more I could have found.
On another note ...... after getting back home (Sth Gippsland) I got wondering about the rocks that set the SDC off so I got them out. Two of the rocks reacted to a magnet but one didn't?????? I checked with the SDC again & it was still giving a signal so I broke the quartz up into six smaller pieces & one of those was still giving a signal so I carefully chipped at it with a hammer & low & behold out fell another small piece of gold.
In case anyone comes across this situation in future... I placed a piece of heavy steel on a cement floor of my shed & put a length 900mm off cut of PVC pipe on the steel. Then I dropped the quartz down the tube & hit it from above with a crowbar..... it worked a charm.
Now I'm hooked & can't wait to get back among it using the advise given.
Thanks again to everyone.
Rob.

 

[mbasko]

One thing I found today staying on sensitivity 4 was that I picked up about 3 hotrocks today.

Just on the "hotrocks" - make sure you still check them. The specci on the top right was a small nugget & several specks completely encased in ironstone. I thought it was another hotrock but it brightened up once I turned it over on one side. Cracked it with my pick & could see the gold specks through it.

 

[midlifecrisis]

I run my threshold on 2 or 3 and sensitivity 4 or 5, but I don't use the standard head phones,I got a lead and set of Sun Ray from Nedad best set I have ever used.
I was in a flogged area and got 17 peices for 1.98gs.
When I get a target scrap it out divide in half push the half with out the target back in the hole do that a couple of times and you will get your target in know time
Cheers

 

[isolation]

Last time I went out I ran at 3 and 3, which worked well on the ground I was exploring. Threshold at 2 seemed too low for my ears, and sensitivity at 4 was a bit unstable for the location. I will definitely try a higher sensitivity in the future if the ground allows it.