Slow sweep speed fact or fiction?

[Ism]

I have a habit of testing claims made about VLF detectors because like statistics...68% are made up. We all have unique conditions to deal with in our specific environments so my experience may not be relevant to another.

First off let me assure everyone that I understand slow sweep speed. PI machines love a slow sweep and I have verified this claim. It is claimed that the Sov loves a slow sweep speed and the slower the better. When I started using the Sovereign, I felt at home with it because it acts just like the Whites TDI in its response to targets. Although the TDI has low pitch for high conductor (go figure?) the way it performs is very similar except for one thing....slow sweep speed. I have tested and tested the Sov and it is a nice deep detector but only when sweeping at a brisk speed, like 2ft/sec.
remember, this is a clean area with neutral soil If I do that I can hit on every coin in the cemetery 9" being the deepest when I made the cemetery last spring. If I go slow I can barely hit the quarter at 6". I can actually gain 4 inches in air-testing on a dime by using a brisk sweep. I have also used the technique out in the field. Feeling like I may have gotten lucky on a couple finds, I slowed down the sweep but got no target signal.

Here's my understanding how a VLF works;
Consider a dip in the road. The slower you go, the less you feel the effects of gravity. Speed up and the effects of the dip become more acute. Too fast and you skip over the dip without feeling the effects. So there is a sweet spot between slow and fast sweep.
This is how the phase shift sees the field produced by the target. It averages for GB the minerals in the soil. When going over a deep target slow, the circuitry adjusts for the subtle change. When passing over it fast, it doesn't have time to compensate and reacts to the change in phase. Of course, too fast and there is no time for the circuitry to process the signal so it ignores it.

I have performed test after test on VLF and never in my experience did the VLF's perform better at a slow speed. With that said, highly mineralized ground, saltwater, and trashy situations are a game changer. Those places a slow sweep is better for obvious reasons.
Another thing to consider is the amount of iron falsing one gets from a faster sweep. If you want a nice quiet search and less bent nails dug, slow is the way to go. As far as slow sweep in iron and trash....the jury is out.
Simply because I've dug a couple dimes that only signaled at the faster sweep speed.

Please don't take this as an attack on the advice of the experts. Like I said, environment can make all the difference and I am only one voice in the Sovereign world.
I may have to make a video to prove my claims but if you have a test garden, bed, or cemetery, it might be prudent to see for yourself.
Ran

 

[GunnarMN]

Ism, you should write a book , I think you are right , thats why I hunt in pinpoint all metal in the woods, because some times i cant swing the coil fast enuff to get a good target to signal whear as in pinpoint i can get a great response at a slow speed , like when the coil is in between branches and sticks i then can clear the spot and switch to disq and check the target. , and i niticed during my breef ownership of the Infinium that yes a slow sweep is needed. great post you have

 

[Neil]

Ran there are indeed alot of bogus claims/statements about detectors and detecting. If we all just passed along info of what we knew and not what we read somewheres else, we would help each other out so much more.

Regarding the Sov slow sweep, the Sov is very slow to recover from one target to the next in disc mode. Since you dont know when your hunting what is in the ground, a slow sweep benefits it to help it overcome this. Try two coins side by side, a few inches apart, either in ground or on top of the ground, and note the sweep speed you have to use to isolate each target. Doing this shows you how every target in the ground, especially in a littered area, requires the Sov to be worked slow to isolate up each target. The Sov wiggle is another example of what you must do with a Sov to get the best ID. Even in a clean area with just a single target, you have to eliminate the Sov reading the adjacent ground(by doing the wiggle).

Another claim you will see is that the Sov does not air test well. I find this statement to be false. I guess in order to give this statement any kind of crediblity one has to have a benchmark of what is standard for air tests with certain sized coils and sensitivity settings on various detectors and except for a few I have owned (such as a shadow X5), they all seem to air test within a few inches of each other.
There was a thread here a short while ago with several people throwing it out there that the Sov doesnt air test well so I tested my Sov GT with a nickel and found that on the highest sens setting, in disc mode, I could repeatedly hit the nickel 12" - 13". This was measured with a plastic ruler. That is with a 12X10 SEF coil. The 10" Tornado coil tests about the same on it, I remember testing the two of them when I first got the SEF coil and the SEF will hit a little sharper and of course over a broader range, but depth is about the same. Maybe you can test your GT this way also and see what you come up with? This GT has the dixie mods(tones set a little higher for one thing).

 

[bootyhoundpa]

you more less answered your own question.......i agree with you that slow sweep speed is usually not needed in mild soil with few targets....but in trashier hot soil as you said it is a whole different ball game... in a relatively clean farm field or beach i usually swing away until either a signal or null gets my attention..at that point i find it nessecary to adjust my swing speed and sometimes settings to the targets liking--make that target sound as good as you can prior to digging it up--depth ,shape and composition are some other key factors which will often effect sweep speedand signal response...

 

[Tin Fin]

Neil,

I did a search after reading this post and couldn't find anything - what are Dixie Mods?

 

[deepdiger60]

Neil,

I did a search after reading this post and couldn't find anything - what are Dixie Mods?

Tin Fin it should be in here
http://www.findmall.com/list.php?22

 

[Rick(ND)]

My hunting is mostly in old parks, school yards and ballfeilds and I find the only way to get those deep signals is by going slow and sometimes very slow to get the signal first then going over just that signal and only that signal swinging faster will make the signal better, but swing faster you will not even hear the signal at all. I am not talking on the surface to 4 inches, but the ones 8 inches or deeper, this I have learned from experiences over and over again. On doing the air test as some say never get the signal close then swing further from the coil as it has locked on and will show actually further depth that starting at 15 inches and gradually get closer to the coil. Then see how close you can get to get a clear repeatable signal. I feel once it sees a good target it is trying to lock on and will get better every time it sees the target, if it sees it close first you will be able to get further away from the coil.
Most of my finding about the Sovereign, which is a BBS is from actual in field use, not from test gardens or air test and why I recommend in field test on actual targets is the only way to do test.

Rick

 

[Tin Fin]

Thanks DD - I didn't realize I had to change the date at the bottom of the screen when searching... duh!

 

[Tin Fin]

Thanks DD - I didn't realize I had to change the date at the bottom of the screen when searching... duh!

Good string of info for me to read up on. Thanks much.

 

[Critterhunter]

I've found two things about the GT. The lower you set the sensitivity (say 3PM) the faster it wants your sweep (not super fast, maybe approaching medium speed or so) to hit on deep targets. However, if you have the sensitivity high (like past 11PM or so) then it for sure wants a super slow sweep speed to hit best on deep targets. You might only get a slight threshold change but that's the indication to zero in on that spot. Once you zero in on it, then yes...the Sovereign then wants fast wiggles or short sweeps to pull the best ID out of the deep stuff. However, there are days when it wants a wiggle, and days it wants short sweeps, and days it wants those from slow to fast. Don't know why that is. You just have to play with that until you see which method and speed gives the best ID for a deep target.

Another factor that might come into play here is that when you max out sensitivity to where the machine is somewhat unstable you have to keep your sweep speed to a crawl in order to keep the threshold from dropping out too much. Swing it fast when it's maxed out and the threshold goes away and doesn't want to come back until you slow down again. That could cost you targets.

Also, with Silent Search mode they say you can swing a bit faster too.

Early on I used to be a big advocate of a faster sweep speed on the GT even with higher sensitivity settings. The more I've used it and practiced on deep stuff I can see that when sensitivity is maxed out a slow crawl is for sure the way to hunt. I'm not saying that will give you the best ID (or even a good hit) on the target, but you aren't looking for that. You're only trying to sense any change in the threshold. Then you zero in on it and do the short sweeps or wiggles to pull the best ID out of it.

Also, the worse the ground gets I think the slower you need to sweep in order for the GT to "see" the deep targets.

 

[Neil]

Neil,

I did a search after reading this post and couldn't find anything - what are Dixie Mods?

they are mods done by a dealer(Im guessing he still is) who used to be a sponsor here. What exactly gets done I dont know. Ive had other Sovs modded by the same guy and not noticed any difference except the higher tone range(anyone can do this, its a pot inside the Sov), and Im not saying this one is any deeper either. Ive got another Sov GT box put away and I really dont want to get it out to test it so I thought maybe you guys could using the same target and sens setting and as Rick says, start by waving the nickel far away from the coil and work your way in and measure and see what you get.

I air tested my Etrac this morning, using a nickel, sens on 30 manual and with the 8" coil I have on it and it gets 10" with accurate reading.

I also tested my AT Gold at max sens, in disc mode, 8" coil and got 10" accurate on the nickel.

My point is weve all read minelabs dont air test well, but Im asking compared to what??? Seems like they do well to me.

 

[Ron from Michigan]

Form my experience with the Sovereign larger coils requires a lower sensitivity adjustment and a slower sweep speed.I agree for the max depth with the Sovereign a slow sweep must be used for any size coil.My hypothesis has always been a Sovereign with the 800 coil is no slough with depth at a moderate to fast sweep speed.Last August in a seeded hunt there was two negative factors against the Sovereign, fresh buried coins and a fast sweep speed required.The XS with the 800 coil exceeded expectations for dimes buried 5-6 inches.Another thing I noticed the Sovereign allowed me to use the max time add coins on these hunts after the first 15 minutes these fields were cleaned out and most hunters gone but the Sovereign was still recovering coins until the time was called.HH Ron

 

[Critterhunter]

Ron, so you have found that with a large coil (like say an S-12 or 12x10) that a lower sensitivity setting works better for IDing deep stuff? With my 15x12 I found that to be true. It seemed I'd get better hits on deep targets with sensitivity much lower than what was max stable, at say around 1:30 to 3PM it seemed to give the best ID on deep stuff, and even though say 11PM was still stable the target would seem to degrade in ID and act like trash. I think I even had a few targets null out on me when I maxed out sensitivity with that coil.

With the 12x10, though, I'm leaning towards max stable sensitivity being deeper/better for deep targets than something lower. I've not made up my mind on that for sure yet but in my tests it sure seems the 12x10 wants to ride the edge (even into somewhat unstable conditions) to give best response on deep targets. Haven't made up my mind on that for sure yet though, but if it's any indication I've been prefering to max out sensitivity with it to where the threshold is even a good bit unstable and hunt that way. I don't seem to have a hard time getting deep stuff to ID with it set that high, but as said I might change my mind on that down the road with more hunting/testing.

I think (I might be wrong...Gunner, care to chime in?) that Gunner also found with his WOT coil that setting sensitivity a good bit lower (say 1:30 to 3PM) than max stable sensitivity seemed to give him the best depth/ID on deep targets too. Could have sworn I remember reading him saying that, but could be wrong,

I think there might be a point that is reached in size with a big coil that it is taking in too much ground matrix and the target quality starts getting lost in the "glare" from the ground signal. By lowering the sensitivity a good bit below max stable it lights up the ground less and makes the target quality less washed out by the ground signal. That's just a theory, though. Even if a big coil gives best ID at depth with a lower sensitivity setting than what is max stable, that doesn't mean that it necessarily is getting less depth than a smaller coil with maxed out sensitivity. But, on the other hand, I found that the 15x12 didn't seem to give me as good of depth on land (many of my sites are mineralized) as the stock 10" coil by doing this. For some reason it did get deeper than stock in the sand though, and my beaches are mineralized too.

I'm willing to bet that this changes with better soil. If the soil isn't highly mineralized then max stable sensitivity probably gives a big coil it's best hit on deep targets, but if the soil is mineralized then lowering it to say 1:30 to 3PM might be best for ID stability at depth.

What's your opinion on this?

 

[Critterhunter]

By the way, on air testing...On my Explorers I've been in areas where I've laid a dime on the ground and couldn't get more than 3 or 4" of depth on it. The only thing I can figure is that without the ground load between the coin and the coil the machine gets confused because it doesn't have anything to compare it to. I'm sure the Sovereign would do the same thing if conditions are right. Whether that's due to mineralized ground being under the coin laying on the surface and not between the coin and the coil...I don't know. Maybe the machine then thinks the coin and the ground signal are "one" and should be ignored, and somehow it's looking for something in between the coin/ground signal and the coil as the target? I've also read this happening to other Explorer users. Again, not saying it's unique to the Explorer. I'm sure the Sovereign can get confused the same way. Just so happens that I've only read that wierd experience when using the Explorer.

But I would agree with Neil....I used to think Minelabs didn't test well but I've got some pretty good air testing depths out of my GT with various coils. Even the S-5...It easily hits about 7 or 8" on a silver dime in the air. However, in the past I've read of many Minelab users saying that they don't air test well. Perhaps that's when they are air testing on bad mineralized ground and it's doing what I described above? Maybe that makes the difference, and in milder soil a coin on the ground air tests well, but with very bad soil the machine gets confused?

 

[OldBeechnut]

[size=medium]At most of the beach's I hunt, Mid-Atlantic Area, wet-sand only


I get alot of questions and people telling me I swing to fast in my video's............One of the Idea's about hunting in Pp with a remote discrimination switch, you can swing faster...run higher sensitivity, cover more area, and hit deeper..many of the old hunters that once posted here on this same forum said about the Sovereign....
And I do believe one of the first, was Gary Keithline "Guvner" to use "Reverse Discrimination........Hunting in PP"[/size]
http://www.frontiernet.net/~jvokes/reverse.htm

bbsailor
Remember, in the all-metal mode there is no fasling as there would be in the discriminate mode. So hunt in the all-metal mode at max sensitivity.

CJC, when is your next book coming out?

Re: Sovereign / Excal All Metal Article

Posted by: Walter L.I. [ Send a Message ]
Date: February 24, 2006 01:32AM

Registered: 6 years ago
Posts: 385


Hi CJC, I had to read your article quite a few times for things to sink in.You have put quite a bit of thinking in to it.The Sovereign-Wot-S12 is my main weapon of choice on wet sand and I always hunt in All-Metal and check target in Disc. using a remote switch as (bb Sailor) stated [size=large]I also feel you can scan a beach quicker in all-metal compared to hunting in Disc.[/size] which you really need to move at a snails pace.After using all-metal for a few years i can normally tell if it is a coin or good target like you said it is much sharper response unless it is real deep without even checking in Disc. for the obvious good tone.Good Luck! Walter

Bottom line is to know your detector and location.............And use what works best.

 

[Ism]

Wow, thanks for all the kind replies. I was expecting to get clobbered but you guys confirmed what I was finding.
Yes I have done the dounble coin test, in fact two coins together in the ground sound like a piece of heavy copper wire sometimes. (a long target). I've also done a flat and dimensional nail-coin-nail-coin airtest. Thats another story but it wasn't pretty. My sweep speed isn't all that fast 2ft/sec but its fast enough to get a response from a deep target and then I can go back and isolate it. You could say I go through trash like I go through water across the road, when I hit it I slow way down. I also monitor the background hum for the nulling associated with iron. I see how experienced users become one with their machine and why the Sovereign has such a following. I've got kind a "jones" to get out and hunt with the Sov every day because its so much fun to hunt with.

 

[Critterhunter]

I should clearify...I think Minelabs CAN air test well, but I also think that in certain situations they CAN air test badly too. Too many people have said they air test badly for it not to be true in some situations. Like I said, I think it might have something to do with what kind of ground the coin is laying on. I think the machine gets confused and starts disgarding the coin as part of the ground matrix.

We all know that sometimes when you dig a hole the coin (still further down in the hole and not disturbed) can vanish when you go to sweep over the hole that was dug. I think these machines need to see the ground load in order to find the coin in it. If the ground load changes and the machine hasn't had time to adjust to it then that's when I think strange things can happen.

All the above being said, I still feel that a Minelab will get better depth on a long buried coin than it will in an air test. Not just because of the halo effect around the coin, but also because the machine needs the ground load to really perform at it's peak.

Just do a search for "doesn't air test well" or words like that in the Explorer or Etrac forum and you'll find messages on this subject. I just did a quick look to see if I could find threads where people were getting only a few inches of depth on a surface coin but couldn't find any. I know I've read that at least a few times over the years in different places, and it's happened to me once or twice.

 

[Critterhunter]

That is with a 12X10 SEF coil. The 10" Tornado coil tests about the same on it, I remember testing the two of them when I first got the SEF coil and the SEF will hit a little sharper and of course over a broader range, but depth is about the same.

Neil, for what it's worth. In my testing of the 12x10 versus the 10" Tornado on a buried silver dime at 3PM sensitivity setting the Tornado could not hear the coin. I didn't touch the sensitivity setting and with the 12x10 it could easily see the coin. Add into that that often the 12x10 allows me to run at much higher sensitivity settings at some of my sites and I think it has more depth potential. I've dug wheats in dry conditions with the 12x10 deeper than I ever dig with the Tornado under the same dry conditions at the same sites. That being said, to date the deepest coins I've dug were around 11" with the Tornado. I haven't hunted enough known deep coin spots with the 12x10 yet to see if it can better that depth.

 

[Neil]

I should clearify...I think Minelabs CAN air test well, but I also think that in certain situations they CAN air test badly too. Too many people have said they air test badly for it not to be true in some situations. Like I said, I think it might have something to do with what kind of ground the coin is laying on. I think the machine gets confused and starts disgarding the coin as part of the ground matrix.

We all know that sometimes when you dig a hole the coin (still further down in the hole and not disturbed) can vanish when you go to sweep over the hole that was dug. I think these machines need to see the ground load in order to find the coin in it. If the ground load changes and the machine hasn't had time to adjust to it then that's when I think strange things can happen.

All the above being said, I still feel that a Minelab will get better depth on a long buried coin than it will in an air test. Not just because of the halo effect around the coin, but also because the machine needs the ground load to really perform at it's peak.

Just do a search for "doesn't air test well" or words like that in the Explorer or Etrac forum and you'll find messages on this subject. I just did a quick look to see if I could find threads where people were getting only a few inches of depth on a surface coin but couldn't find any. I know I've read that at least a few times over the years in different places, and it's happened to me once or twice.

The statement I made was that people casually say that minelabs do not air test well. I disagree with that based on comparisons to most other detectors. Simple as that.

 

[dewcon4414]

Id be more apt to say the MLs dont like space between the coil and soil than it doesnt air test well. What i do notice is my Xcal sees the hole more often than the Exp.... if the Exp says it there you hear it. My Xcal tends to loose the target..... its not a big deal once you realize targets disappearing really are still in the hole and may have dropped below its ability to see it. Havent said much, but if high sensitivity does require slower sweep speed it would make good sense on the Xcal since you are at the mercy of the current many times. PP at that point would have a bigger depth advantage.

Dew