Metal Detector Settings Guide
You cannot discriminate out pull-tabs without losing gold rings — they read the same. Frequency and coil size are trades, not qualities.
Discrimination: —
You cannot discriminate out pull-tabs without losing gold
A detector does not identify metal. It measures conductivity and reports it as a number. Iron sits at the bottom, silver at the top, everything else in between. Gold jewellery reads low because it is alloyed, thin and small — and aluminium pull-tabs land in exactly the same part of the scale. Not near it. In it.
| Target | Reads around | Overlaps pull-tabs? | |
|---|---|---|---|
| Iron and steel | 0–20 | no | Nails, bottle caps, junk. The one thing worth discriminating out, and even then it hides good targets. |
| Aluminium foil | 20–32 | YES | Gum wrappers and food foil. Sits right on top of small gold. |
| Small gold jewellery | 24–45 | YES | Thin chains, small rings, earrings. Low conductivity because it is small and alloyed. |
| Aluminium pull-tabs | 30–55 | — | THE PROBLEM. Occupies the same band as gold rings and there is no setting that separates them. |
| Larger gold rings | 40–62 | YES | A heavy band can read higher than a pull-tab, but the ranges still overlap heavily. |
| Nickels and zinc pennies | 45–70 | YES | A useful landmark: if your machine calls a nickel 55, gold sits below that. |
| Copper pennies and brass | 70–85 | no | High conductivity, loud and unambiguous. |
| Silver coins | 82–95 | no | The top of the scale. The easiest targets to identify and the least often confused. |
So the discrimination setting that silences the tabs silences the rings. There is no cutoff anywhere on the scale that removes one and keeps the other — this page checks all 101 of them and none exists. Every experienced detectorist digs pull-tabs, not because they enjoy it, but because the alternative is not finding gold. Anyone describing a machine that separates the two is describing a machine that does not exist.
Iron is the exception worth taking. It sits below everything else with a clear gap, so discriminating out iron alone costs you no gold — though it will still mask good targets lying next to nails, which is why serious hunters often run no discrimination at all and listen instead.
Frequency is a trade, not a quality
Low frequencies couple better with large, highly conductive targets; high frequencies with small, poorly conductive ones. A 5 kHz machine will out-depth an 18 kHz machine on a silver coin and lose to it badly on a thin gold chain. Neither is more powerful — they are tuned to opposite ends of the same scale.
| Frequency | Best at | Worst at | |
|---|---|---|---|
| Very low (2–5 kHz) | Silver coins, large copper, deep high-conductivity targets | Small gold, thin chains, tiny targets of any kind | Relic and coin machines. Excellent depth on the targets it suits and nearly deaf to small gold. |
| Low (6–9 kHz) | General coin shooting, a good all-round compromise | Very small gold and fine prospecting targets | Where most entry-level single-frequency machines sit. |
| Mid (10–15 kHz) | Jewellery, mixed targets, most beach work | Nothing badly, which is why it is the common default | The best single choice if you only get one and do not know what you will find. |
| High (18–30 kHz) | Small gold jewellery, thin chains, small low-conductivity targets | Deep silver, and it is noisier in mineralised soil | Noticeably better on the targets people most want and worse on the ones they most find. |
| Very high (40–70 kHz) | Gold prospecting — small natural nuggets and specimens | Coins and anything large or highly conductive | Specialist prospecting machines. Not a general-purpose detector. |
Every row names something it is bad at, because every one of them is. Multi-frequency machines transmit several at once and split the difference, which is why they cost more — and why they are not simply better at everything.
A bigger coil is not simply deeper
It is deeper on large targets and worse on small ones. The field spreads over the coil's area, so a fixed small object occupies a smaller share of it — the response falls with the square of the diameter, which is much steeper than people expect:
| Coil | Small-target response | Good for | Costs you |
|---|---|---|---|
| Small (4–6″) | 256% | Trashy ground, tight spaces, separating targets an inch apart | Much less ground covered per sweep, and less depth on big targets. |
| Standard (7–9″) | 100% | General use, the coil most machines ship with | No particular weakness, no particular strength. |
| Large (10–12″) | 53% | Open ground, more depth on coin-sized and larger targets | Loses small targets, and merges close targets into one signal. |
| Very large (13–15″) | 28% | Covering fields fast, deep large targets | Heavy, poor on small gold, and useless in trash. |
Going from an 8″ coil to a 15″ leaves you under a third of the small-target response. A big coil also averages everything beneath it together, so in trashy ground it merges a good target and a nail into one confused signal that a small coil would have separated cleanly.
The rule of thumb that a coil detects a coin to roughly its own diameter is a rule of thumb. It assumes clean, unmineralised soil, and most soil is neither. Treat any depth figure in an advertisement as measured in air.
Things that matter more than settings
- Ground balance, every time you move. Mineralised soil produces a signal of its own, and a machine that is not balanced to it is deaf and noisy at once.
- Sweep slowly and keep the coil flat. Lifting it at the end of a sweep loses the depth you paid for. Most people sweep about twice as fast as they should.
- Overlap every sweep by half a coil. The detection field is not the coil outline; missing ground is the commonest reason for missing targets.
- Learn one machine properly. The difference between a beginner and an expert on identical hardware is far larger than the difference between hardware.
- Get permission, and fill your holes. Detecting on land you do not own without asking is trespass, and on protected sites it is a criminal offence in most countries. A neatly cut and replaced plug is why permissions get renewed.
How to use
- Pick where you are hunting and take the settings as a starting point.
- Dig the pull-tabs. There is no setting that keeps gold without them.
- Ground balance every time you move to new soil.
- Sweep slowly, keep the coil flat, and overlap by half a coil.
Frequently asked questions
Why does my detector sound the same on gold and pull-tabs?
Because electrically they are the same. A detector measures conductivity, not metal type, and gold jewellery reads low because it is alloyed, thin and small. Aluminium pull-tabs land in exactly the same part of the scale — not near it, in it. No setting separates them because there is nothing to separate.
Should I use discrimination to skip trash?
Only for iron, and even that has a cost. Any cutoff high enough to silence pull-tabs has already silenced gold rings. Every experienced detectorist digs tabs, not because they enjoy it but because the alternative is not finding gold. This page checks every cutoff on the scale and none of them work.
Is it worth discriminating out iron?
Usually yes. Iron sits at the bottom of the scale with a clear gap above it, so removing it costs you no gold. It will still mask good targets lying right next to nails, which is why many serious hunters run no discrimination at all and learn to judge by sound instead.
What frequency should I use for gold jewellery?
High — around 18 to 30 kHz. Higher frequencies couple better with small, low-conductivity targets, which is what most gold jewellery is. The trade is real: the same machine will be worse on deep silver coins and noisier in mineralised soil.
Is a higher frequency detector better?
No, it is different. Low frequencies do better on large, highly conductive targets like silver coins; high frequencies on small, poorly conductive ones like thin gold. A 5 kHz machine out-depths an 18 kHz machine on a silver coin and loses badly to it on a gold chain. Neither is more powerful.
What is multi-frequency for?
Transmitting several frequencies at once so the machine can respond across the range rather than at one point on it. That is genuinely useful, particularly on salt beaches, and it is why those machines cost more. It is not the same as being better at everything — it is splitting the difference well.
Does a bigger coil detect deeper?
On large targets, yes. On small ones it is worse, because the field spreads over the coil area and a small object occupies a smaller share of it — the response falls with the square of the diameter. Going from an 8 inch coil to a 15 inch leaves under a third of the small-target response.
When should I use a small coil?
In trash. A big coil averages everything beneath it together, so a good target next to a nail becomes one confused signal, where a small coil separates them cleanly. Old picnic grounds, fairgrounds and long-used parks are where a small coil finds what everyone else has walked over.
How deep will my detector actually go?
The rule of thumb is that a coil detects a coin to roughly its own diameter — so about 11 inches for an 11 inch coil. It is a rule of thumb and it assumes clean unmineralised soil, which most soil is not. Treat any depth figure in an advertisement as measured in air.
What is ground balance and do I need it?
Mineralised soil produces a signal of its own, and ground balancing tells the machine to ignore it. Without it the detector is simultaneously noisy and deaf. Rebalance whenever you move to different soil, which in practice means several times in a session.
What matters more than settings?
Sweeping slowly with the coil flat to the ground, overlapping each sweep by half a coil, and learning one machine properly. Most people sweep about twice as fast as they should and lift the coil at the end of each pass, which throws away the depth they paid for. The gap between a beginner and an expert on identical hardware is far larger than the gap between hardware.
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