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Can someone please explain the concept of "gain"...
- Thread starter MikeK
- Start date
DukeOBass
Active member
Hi MikeK
Gain setting will either amplifier your sound or not. At a setting of '1' there is no amplification. Big targets are going to sound "BIG" and small targets are going to sound "SMALL". You will have a better ability to judge what is what.
At a setting of 10 you will not be able to tell much difference between mid-size and large targets but weak targets will be greatly amplified.
Gain setting will either amplifier your sound or not. At a setting of '1' there is no amplification. Big targets are going to sound "BIG" and small targets are going to sound "SMALL". You will have a better ability to judge what is what.
At a setting of 10 you will not be able to tell much difference between mid-size and large targets but weak targets will be greatly amplified.
Chris(SoCenWI)
Well-known member
Mike,
This confuses many. Basically gain is like the volume knob on a stereo. When you turn up the volume you make things louder; both softer music and louder music get louder. If you have the volume turned down very low there may be times when you can't hear the soft music at all.
Sensitivity on the explorer sets how big a signal needs to be in order to get processed.
I'm not sure what is your level of electronic's savvy, I'll assume little.
Imagine a lake; it can have a perfectly smooth surface on a calm day or big waves if it is windy, and points in between. Sensitivity settings on the explorer would be akin to saying: "Don't tell me about any wave unless it is at least this big" If it is a perfectly calm(No targets or electrical interference) day you could have the sensitivity cranked up high and still have a smooth threshhold and a quiet detector. Once the wind picks up(lots of targets or electrical interference nearby) you will hear a constant chatter at high sensitivities. You can turn your sensitivity down until you are only picking up the biggest waves(bigger/shallower targets) .
Couple of things to keep in mind...
The power transmitted by the Explorer is constant, nothing you can do other than turning the unit on or off makes any difference on the transmit circuit, well almost (noise cancel shifts the frequencies of the transmit slightly, but doesn't affect amplitude). As you sweep the coil over the ground different targets in the ground change what the recieve coil "sees" of the the transmitted signal. Deeper/smaller targets make a smaller change; bigger shallower more. Sensitivity determines how big the change has to be before the machine tells you about it.
Normally you try to keep the sensitivity up as high as possible; the problem is electrical interference, almost everywhere we detect except for way out in the boonies is usually somewhat close to power lines or other sources of electrical noise. This noise also affects what the recieve coil sees. Put your detector in manual inside with the TV on and see how high you can turn up the sensitivity before it goes crazy.
Auto sensitivity generally strives for a smooth threshhold, in other words it decides how big of waves it should report on. Many, me included, feel that it wants to ignore most of the little ones in places with many targets or lots of electrical noise. Auto can crank sensitivity UP or DOWN by quite a bit depending on conditions.
Basically gain has more to do with your headphones and hearing ability. At real high gains all signals get amplified alot and it is harder to tell deep signals from shallower ones. DEEP ON affects the gain somewhat in that it changes it to a non-linear function; smaller signals get boosted more that bigger ones.
Hope this helps
Chris
This confuses many. Basically gain is like the volume knob on a stereo. When you turn up the volume you make things louder; both softer music and louder music get louder. If you have the volume turned down very low there may be times when you can't hear the soft music at all.
Sensitivity on the explorer sets how big a signal needs to be in order to get processed.
I'm not sure what is your level of electronic's savvy, I'll assume little.
Imagine a lake; it can have a perfectly smooth surface on a calm day or big waves if it is windy, and points in between. Sensitivity settings on the explorer would be akin to saying: "Don't tell me about any wave unless it is at least this big" If it is a perfectly calm(No targets or electrical interference) day you could have the sensitivity cranked up high and still have a smooth threshhold and a quiet detector. Once the wind picks up(lots of targets or electrical interference nearby) you will hear a constant chatter at high sensitivities. You can turn your sensitivity down until you are only picking up the biggest waves(bigger/shallower targets) .
Couple of things to keep in mind...
The power transmitted by the Explorer is constant, nothing you can do other than turning the unit on or off makes any difference on the transmit circuit, well almost (noise cancel shifts the frequencies of the transmit slightly, but doesn't affect amplitude). As you sweep the coil over the ground different targets in the ground change what the recieve coil "sees" of the the transmitted signal. Deeper/smaller targets make a smaller change; bigger shallower more. Sensitivity determines how big the change has to be before the machine tells you about it.
Normally you try to keep the sensitivity up as high as possible; the problem is electrical interference, almost everywhere we detect except for way out in the boonies is usually somewhat close to power lines or other sources of electrical noise. This noise also affects what the recieve coil sees. Put your detector in manual inside with the TV on and see how high you can turn up the sensitivity before it goes crazy.
Auto sensitivity generally strives for a smooth threshhold, in other words it decides how big of waves it should report on. Many, me included, feel that it wants to ignore most of the little ones in places with many targets or lots of electrical noise. Auto can crank sensitivity UP or DOWN by quite a bit depending on conditions.
Basically gain has more to do with your headphones and hearing ability. At real high gains all signals get amplified alot and it is harder to tell deep signals from shallower ones. DEEP ON affects the gain somewhat in that it changes it to a non-linear function; smaller signals get boosted more that bigger ones.
Hope this helps
Chris
Mike (Virginia Beach)
New member
I like that. I run mine at 5 most of the time. Works well for me.
Soon I will be coming back to this forum and hopefully posting a few nice finds again. The beach season has wound down here and I've pretty much gotten all the gold and diamonds there are to get for now. As the cool weather approaches, I will return to the fields and the woods in search of silver, copper, and lead once more.
I'm looking forward to hanging the Excal up for the winter and swinging the Explorer SE once again!
Soon I will be coming back to this forum and hopefully posting a few nice finds again. The beach season has wound down here and I've pretty much gotten all the gold and diamonds there are to get for now. As the cool weather approaches, I will return to the fields and the woods in search of silver, copper, and lead once more.
I'm looking forward to hanging the Excal up for the winter and swinging the Explorer SE once again!
I'll bet you Andy Sabich and others are taking notes for their next book.
The following is intended for the guy who asked the question as you already know this. The only thing I would add is on my SE, turning gain above say 7, it tends to false more and become unstable even at low manual sensitivity and especially in auto sensitivity. This may be my specific machine but others with SE's have noticed this as well. My normal gain setting is seven and I will turn it lower if I really want to be able to distinguish the soft, faint, small or deeper targets from the louder, larger shallow targets, and especially with deep on. But Chris is exactly correct.. sensitivity is like a screen that filters which signals you can hear in your headphones, and which ones the machine doesn't report. Regardless of the setting, the machine always receives these signals, you, by adjusting the sensitivity are deciding which ones you want to be told about. Allot of the tiny non repeating signals come from both electrical interference and more commonly the mineralization in the soil itself. When the soil is really saturated with water it is more conductive to both weak and strong signals. This can be very apparent in wet sand areas at a salt water beach and after long steady rains. If one notices lots of false, erratic, non repeating signals; many times you can reduce the number of these false signals by lowering your gain first and then if still necessary lowering your sensitivity. Almost like they are both volume knobs on a stereo in sequence, one after the other. The first in line is the sensitivity (deciding which signals are strong enough to report) and the second is your gain which then amplifies the volume of those signals that are left AND ALSO THOSE SIGNALS THAT WERE NOT LARGE ENOUGH TO REPORT THE FIRST TIME. I've noticed on my machine that the sensitivity/gain relationship is not absolutely perfect. At a gain setting higher than 7 the order of first sensitivity and then gain begins to smear. Even though my sensitivity, set at a lower setting is filtering out the weaker garbage signals so that they are not audible to me, a high gain setting may then multiply that once, to weak, inaudible signal to a level that I can now hear, and in effect, defeat my sensitivity's settings very purpose. My machines sens/gain relationship tends to be very linear until my gain setting goes above 7 or sometimes lower when in areas of heavy soil mineralization or in excessively wet soil. My theory is that because the Explorers are auto ground balance machines, that they, just like an expert user would, set the ground balance to be slightly positive (still reporting small amounts of the soil mineralization itself) and with a very high gain setting, those slight signals then begin getting amplified to a now audible level. I'd bet that's why. In fact, it makes perfect sense that sensitivity, gain and even threshold volume are all linear volume controls in succession, some settings being redundant and counter productive and others being able to extract audibly the tiniest signal possible and everything in between. Welcome to Mine lab, a land of endless growth and opportunity to be better with your machine then the last guy therefore finding the things he missed!
The following is intended for the guy who asked the question as you already know this. The only thing I would add is on my SE, turning gain above say 7, it tends to false more and become unstable even at low manual sensitivity and especially in auto sensitivity. This may be my specific machine but others with SE's have noticed this as well. My normal gain setting is seven and I will turn it lower if I really want to be able to distinguish the soft, faint, small or deeper targets from the louder, larger shallow targets, and especially with deep on. But Chris is exactly correct.. sensitivity is like a screen that filters which signals you can hear in your headphones, and which ones the machine doesn't report. Regardless of the setting, the machine always receives these signals, you, by adjusting the sensitivity are deciding which ones you want to be told about. Allot of the tiny non repeating signals come from both electrical interference and more commonly the mineralization in the soil itself. When the soil is really saturated with water it is more conductive to both weak and strong signals. This can be very apparent in wet sand areas at a salt water beach and after long steady rains. If one notices lots of false, erratic, non repeating signals; many times you can reduce the number of these false signals by lowering your gain first and then if still necessary lowering your sensitivity. Almost like they are both volume knobs on a stereo in sequence, one after the other. The first in line is the sensitivity (deciding which signals are strong enough to report) and the second is your gain which then amplifies the volume of those signals that are left AND ALSO THOSE SIGNALS THAT WERE NOT LARGE ENOUGH TO REPORT THE FIRST TIME. I've noticed on my machine that the sensitivity/gain relationship is not absolutely perfect. At a gain setting higher than 7 the order of first sensitivity and then gain begins to smear. Even though my sensitivity, set at a lower setting is filtering out the weaker garbage signals so that they are not audible to me, a high gain setting may then multiply that once, to weak, inaudible signal to a level that I can now hear, and in effect, defeat my sensitivity's settings very purpose. My machines sens/gain relationship tends to be very linear until my gain setting goes above 7 or sometimes lower when in areas of heavy soil mineralization or in excessively wet soil. My theory is that because the Explorers are auto ground balance machines, that they, just like an expert user would, set the ground balance to be slightly positive (still reporting small amounts of the soil mineralization itself) and with a very high gain setting, those slight signals then begin getting amplified to a now audible level. I'd bet that's why. In fact, it makes perfect sense that sensitivity, gain and even threshold volume are all linear volume controls in succession, some settings being redundant and counter productive and others being able to extract audibly the tiniest signal possible and everything in between. Welcome to Mine lab, a land of endless growth and opportunity to be better with your machine then the last guy therefore finding the things he missed!mattockman
New member
You just got some excelent info from Chris and digitrich....but its up to you to go out and experiment with it....paying close attention to what is happening....this forum is so awsome and rich with info ......Gotta love it....owning the best(IMHO) Detector and having a great resource like this forum to guide you alone.......Wish Ya Luck!! 
Mick in Dubbo
New member
I enjoyed your post and have a question. you mentioned in your post, that the Explorer's are an auto ground balanced machine. I've been wondering about that, and even asked a question here a while back about that point (with no answer.) I assumed that they are a fixed ground balanced machine as there is no mention in the instruction manual about them being anything else. I was wondering where you found out about them being an auto ground balanced machine if you could, as I'm interested to know? (This is a genuine request and meant as nothing more or less than that.)
Thanks.
Mick Evans.
Thanks.
Mick Evans.
Hard Nosed Dave
New member
a volume "booster" of the signal that comes off a positively detected target that the Explorer has managed to locate.
These signals also get boosted when it has come off a target that is a hot rock or ones that can also be composed of concentrations of dense iron oxide or targets that are made up of other types of metal oxide concentrations.
It also amplifies a lot of other unwanted, spurious signals from other background sources.
Such "false"signals don't repeat when you pass the coil over what is or might seem, a possible target composed of "whole" metal or tangible oxide concentrations.
Other than naturally occurring metallic mineral concentrations, some targets can also be the completely oxidised remnants of man made objects that can prevent the Explorer from detecting through them or give the Explorer the impression it is a viable solid metal target.
This is especially so when such signals do not repeat at all even when a target may have been located and a detecting approach is done from any angel.
I think it's a good idea to dig a deep signal that repeats. It's most likely going to be a piece of non oxidized metal and there is the odd occasion that it is a piece oxidized metal(possibly a concentrated oxide).
I have actually been digging the smaller less broad signals that null the background threshold(variable volume of this as well ) with some interesting results.
In the past, I have simply walked over these target and never considered them as a possible viable target to dig.
Now I have to go back over all the places I've been to over the last 7 years and re hunt them by using this method of detecting.
GAIN is a control that gives a repeatable detected target an audible dynamic depth of field.
If you you correlate that with your depth meter it will also help determine the targets size, to a degree.
Set GAIN at it's highest level then you'll have less audible dynamic, as the signal of a detected target within a certain depth, will sound out loud as possible and just as loud as shallow target.
The volume control will reduce ALL or amplify ALL other sound controls of the Explorer, including the GAIN.
Hard Nosed Dave
These signals also get boosted when it has come off a target that is a hot rock or ones that can also be composed of concentrations of dense iron oxide or targets that are made up of other types of metal oxide concentrations.
It also amplifies a lot of other unwanted, spurious signals from other background sources.
Such "false"signals don't repeat when you pass the coil over what is or might seem, a possible target composed of "whole" metal or tangible oxide concentrations.
Other than naturally occurring metallic mineral concentrations, some targets can also be the completely oxidised remnants of man made objects that can prevent the Explorer from detecting through them or give the Explorer the impression it is a viable solid metal target.
This is especially so when such signals do not repeat at all even when a target may have been located and a detecting approach is done from any angel.
I think it's a good idea to dig a deep signal that repeats. It's most likely going to be a piece of non oxidized metal and there is the odd occasion that it is a piece oxidized metal(possibly a concentrated oxide).
I have actually been digging the smaller less broad signals that null the background threshold(variable volume of this as well ) with some interesting results.
In the past, I have simply walked over these target and never considered them as a possible viable target to dig.
Now I have to go back over all the places I've been to over the last 7 years and re hunt them by using this method of detecting.
GAIN is a control that gives a repeatable detected target an audible dynamic depth of field.
If you you correlate that with your depth meter it will also help determine the targets size, to a degree.
Set GAIN at it's highest level then you'll have less audible dynamic, as the signal of a detected target within a certain depth, will sound out loud as possible and just as loud as shallow target.
The volume control will reduce ALL or amplify ALL other sound controls of the Explorer, including the GAIN.
Hard Nosed Dave
Charles (Upstate NY)
Well-known member
[quote Chris(SoCenWI)]Mike,
At real high gains all signals get amplified alot and it is harder to tell deep signals from shallower ones. DEEP ON affects the gain somewhat in that it changes it to a non-linear function; smaller signals get boosted more that bigger ones. Chris[/quote]
Chris that's pretty close except I question the quote regarding Deep On and gain. The gain is non-linear regardless to my knowledge, as you increase the gain the small signals are boosted up in volume however the strong signals remain the same volume level until at the highest gain setting all signals are at the same volume which as you mention makes it difficult to tell which signals are deep versus shallow. Deep On gives deep target signals a boost but in terms of sensitivity settings, not so much volume. With deep on a deep target that is faint and might be chopped at a lower sensitivity setting might get boosted enough to make it past the sens setting. I suspect there is more to Deep on than we know, thats certainly an area for tweaking I'm sure ML didn't pass up.
By the way Deep on works a little differently on the original XS versus the II and SE. Deep on with an XS makes a deep target larger as you sweep across it, which I prefer, thats why an XS is a nickel sucking vacuum, its quite easy to tell an old, deeper nickel from a pulltab just based on the size of the target as you sweep it with deep on. ML changed this with the model II and we lost that wider signal, I'm guessing for improved pinpointing and/or improved response time.
Just my two cents worth.
Charles
At real high gains all signals get amplified alot and it is harder to tell deep signals from shallower ones. DEEP ON affects the gain somewhat in that it changes it to a non-linear function; smaller signals get boosted more that bigger ones. Chris[/quote]
Chris that's pretty close except I question the quote regarding Deep On and gain. The gain is non-linear regardless to my knowledge, as you increase the gain the small signals are boosted up in volume however the strong signals remain the same volume level until at the highest gain setting all signals are at the same volume which as you mention makes it difficult to tell which signals are deep versus shallow. Deep On gives deep target signals a boost but in terms of sensitivity settings, not so much volume. With deep on a deep target that is faint and might be chopped at a lower sensitivity setting might get boosted enough to make it past the sens setting. I suspect there is more to Deep on than we know, thats certainly an area for tweaking I'm sure ML didn't pass up.
By the way Deep on works a little differently on the original XS versus the II and SE. Deep on with an XS makes a deep target larger as you sweep across it, which I prefer, thats why an XS is a nickel sucking vacuum, its quite easy to tell an old, deeper nickel from a pulltab just based on the size of the target as you sweep it with deep on. ML changed this with the model II
and we lost that wider signal, I'm guessing for improved pinpointing and/or improved response time.Just my two cents worth.
Charles
DukeOBass
Active member
Sort of speaking there is. Like I said, the gain will affect the volume that targets of varying size and depths will give you. If you run the gain all the way up there will be no difference in the sound of a large object as opposed to a small object or a shallow object as opposed to a deep target.
Chris(SoCenWI)
Well-known member
I very seldom mess with my set up and forgot there was a seperate Volume and Gain setting. I did accidently reset my explorer in the last month and had a bit of fun getting it back to where it was.
Chris
Chris
I believe the instructional manual mentions them being auto ground balance. There is no such thing as a fixed ground balanced machine because all soils, including soils in the same hole have different amounts of mineralization in them. So if a machine was fixed to one particular mineralization amount, it would not work whatsoever. It's funny how people over look the awesome technology of an explorer automatically ground balancing and adjusting to and for the mineralization of the soil matrix just as you sweep. That, by far, is the single greatest accomplishment of any metal detector. The soil matrix changes constantly. People complain about the Explorers slow response, they forget that the machine is doing a gazillion calculations with each sweep just to compensate for the soil itself. And the fact that they do this with 28 separate frequencies and go deeper and more accurate than any other machine, all at the same time, well what else could a guy ask for? My hat is off to Mine lab and I can't wait till they produce the next version of the Explorer. I will always own a Mine lab. 
Charles, on my SE, deep on doesn't make the volume on my deepies go up as much as you said it makes the sound last longer, so it is easier to distinguish from the shallower, louder, shorter signals. Almost like a selective audio long that only applies to the fainter, maybe deeper signals just not as extreme as audio long itself, but a discernible difference. I had a 1909 fraternity house that had lots and lots of clad. At this particular site, there were lot's of copper 1960 and younger cents, all about 4 inches deep. Under them, every coin 6 inches deep or more was a definite wheat penny, I found two 1909 vdb's (no mint mark) at that depth. Problem was every silver sounding coin ending up being just a modern copper penny and for some reason they were hitting further right on my screen than normal and being a tone hunter first and a display hunter second this was really frustrating me
. So I remembered your posts long ago and switched out of fast into deep and dropped my gain from 7 to 4 and 5 and immediately I dug two dozen wheats. Thank you! Because I hunt in pretty thick trash, I don't get to use deep as much as fast, but there are definitely certain sites where all the older coins are mostly deeper, and regardless of trash, that deep on setting really picks them out from a crowd.
. So I remembered your posts long ago and switched out of fast into deep and dropped my gain from 7 to 4 and 5 and immediately I dug two dozen wheats. Thank you! Because I hunt in pretty thick trash, I don't get to use deep as much as fast, but there are definitely certain sites where all the older coins are mostly deeper, and regardless of trash, that deep on setting really picks them out from a crowd.Mick in Dubbo
New member
Thanks for responding digitrich. I found it under the heading of ground compensation of the instruction manual. It's called digital filtering. I'll ask about that in the class room.
As far as fixed ground balanced machines go (preset ground balance) there are quite a number on the market. I got test test my Ace (which has a preset ground balance) in some noisy ground a couple of weeks back and found (after reading about it) that by reducing the sensitivity and knocking out the first 3 notches, it actually handled the ground fairly well.
Mick Evans.
As far as fixed ground balanced machines go (preset ground balance) there are quite a number on the market. I got test test my Ace (which has a preset ground balance) in some noisy ground a couple of weeks back and found (after reading about it) that by reducing the sensitivity and knocking out the first 3 notches, it actually handled the ground fairly well.
Mick Evans.
Look in the user manual, pg 75 under Technical Specifications, mid page Ground Rejection......Auto Ground Compensation through Advanced Digital Filtering. What's also interesting is under Auto Noise Cancel (scanning) they list - Yes. That might explain that other guys post about him getting better results by not noise canceling, because the machine itself would be switching channels as he swept his coil and eventually find the quietest channel any way.
Hi,
I studied some electronics units at University and 'Gain' from the electronics theory point-of-view, is simply the ratio of the output voltage to the input voltage of an amplifier.
So if i had a black box that took 1 volt input, and produced 10 volts output, then this black-box would have a gain of 10.
Operational amps. which we studied at uni (which come packaged as tiny little chips) often have gain values of 10,000 or 20,000. However they're not very useful like this as its hard to control the signal. Therefore we introduce 'negative feedback' (we take a sample of the output signal and feed it back into the input - but this returned signal is *subtracted* from the input) leads to much lower gain values now of 50, 100 or 200 - something like that - but the signal can now be fully controlled.
Do a google on keywords of 'gain negative feedback' and top of the list is a site on Op. Amps.
http://hyperphysics.phy-astr.gsu.edu/hbase/electronic/opamp2.html
cheers,
rob
I studied some electronics units at University and 'Gain' from the electronics theory point-of-view, is simply the ratio of the output voltage to the input voltage of an amplifier.
So if i had a black box that took 1 volt input, and produced 10 volts output, then this black-box would have a gain of 10.
Operational amps. which we studied at uni (which come packaged as tiny little chips) often have gain values of 10,000 or 20,000. However they're not very useful like this as its hard to control the signal. Therefore we introduce 'negative feedback' (we take a sample of the output signal and feed it back into the input - but this returned signal is *subtracted* from the input) leads to much lower gain values now of 50, 100 or 200 - something like that - but the signal can now be fully controlled.
Do a google on keywords of 'gain negative feedback' and top of the list is a site on Op. Amps.
http://hyperphysics.phy-astr.gsu.edu/hbase/electronic/opamp2.html
cheers,
rob
Mick in Dubbo
New member
Thanks heaps digitrich. The wording is different in my manual. (XS). Reads "Ground compensation- advanced digital filtering."
Mick Evans.
Mick Evans.