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Metal detector discrimination and target ID are the two systems that turn a raw electromagnetic response into a dig or no-dig decision. A VLF detector measures both conductivity and phase shift, then maps those values to a number or a tone. Understanding that mapping—and how to adjust it—is what separates a detectorist who spends a morning digging pull tabs from one who covers the same ground and comes home with coins, relics, or gold.
Across the major brands, discrimination is not a single switch. Garrett uses notch segments and iron audio, Minelab uses Iron Bias and Multi-IQ, XP relies on audio and the X-Y screen, and Nokta builds iron filtering and stability into its scale. The numbers look similar, but a nickel does not read the same on an ACE 300, an Equinox 700, and a Simplex. That is why a detector-specific understanding of target ID matters more than a generic VDI chart.
This guide explains discrimination and target ID from first principles, then maps those concepts onto specific detectors: the Garrett ACE and AT series, Minelab Equinox 700, XP Deus II, Nokta Legend and Simplex, and modern pinpointers with ferrous tone ID. The focus is on real settings and trade-offs you can apply in parks, beaches, relic fields, and gold ground.
If you want to stop guessing at what your detector is telling you and start reading numbers, tones, and notch patterns as a single decision system, this is the starting point.
Quick Reference: Target ID Scales and Iron Controls
| Detector | Target ID scale | Ferrous range | Primary iron control | Notch system |
|---|---|---|---|---|
| Garrett ACE 300 | 0–99 digital | left side of scale | none (disc/notch only) | 12-segment notch bar |
| Garrett AT Pro | 0–99 digital | left side, 40-point iron discrimination | High-Resolution Iron Disc 0–39 + Iron Audio | 12-pixel notch |
| Garrett AT Max | 0–99 digital | left side, 44 iron segments | 44 iron segments + All-Metal Iron Audio | notch discrimination |
| Minelab Equinox 700 | 119-segment, −9 to 40 range | −9 to 0 ferrous | Iron Bias FE/F2 0–9 | notch discrimination |
| XP Deus II | −6.4 to 99 | below 0 ferrous | discrimination threshold | Multi-Notch N1–N3 |
| Nokta Legend | 1–60 accepted default | 1–11 rejected default | Iron Filter 0–9 + Stability 1–5 | manual/auto notch individual IDs |
| Nokta Simplex | 01–99 two-digit | 0–15 common | iron off + notch | 20 notch boxes, 5 IDs each |
How Discrimination and Target ID Actually Work
At the core, a VLF metal detector transmits an alternating magnetic field and analyzes the return signal from a target. Two properties drive the display: conductivity and phase shift. High-conductivity metals like silver and copper produce a sharp, repeatable response and usually register high on the ID scale. Thin or low-conductivity metals like small gold, foil, and many modern alloys produce a lower reading. Ferrous targets—iron, steel, rusted nails—produce a distinctive phase response because their magnetic permeability shifts the signal out of phase with the transmit field.
Target ID converts those electrical characteristics into a number. On the Garrett ACE 300, that scale runs 0–99, with iron on the left, thin non-ferrous in the middle, and thick high-conductivity non-ferrous on the right. The ACE 300's digital readout is more granular than the old analog cursor machines: a coin may hit a narrow 3–5 point range repeatedly, while a piece of foil bounces across a 10–15 point window. Repeatability from multiple sweep angles is the strongest single signal that a number represents a real target, not a fragment.
Discrimination filters targets by conductivity. When you raise discrimination, the detector rejects or silences targets below a threshold. On the ACE 300, the 12-segment notch bar lets you accept or reject any combination of conductivity bands, not just a single cutoff. That means you can reject foil and pull tabs while still hearing nickels and gold, which overlap those ranges on most machines.
The key insight is that discrimination is an estimate, not an identification. Soil mineralization, target depth, size, shape, and nearby trash all shift ID numbers and tones. A silver dime at 8 inches in mineralized soil may read lower and more erratic than the same coin at 3 inches in clean ground. The detector is not naming the object; it is assigning a conductivity response to a zone. Treat the number as a clue, not a verdict.
Target ID Scales Are Not Universal
One of the most persistent myths in detecting is that a target ID number means the same thing across brands. It does not. A nickel that reads 55 on a Garrett ACE 300 may sit in a completely different numeric band on a Minelab Equinox 700 or a Nokta Simplex. The scale itself differs: Garrett uses 0–99 for nearly all models; older Equinox models use −9 to 40 with ferrous from −9 to 0 and non-ferrous from 1 to 40; the Equinox 700 expands that to a high-resolution 119-segment system for finer separation. XP Deus II discrimination runs from −6.4 to 99, while Nokta Legend defaults to rejecting IDs 1–11 and accepting 12–60.
Even within one brand, the same object can read differently depending on frequency and mode. The Minelab Multi-IQ platform stabilizes non-ferrous IDs across simultaneous frequencies—a copper coin often reads 21 whether in Multi, 10 kHz, or 15 kHz—but iron falses behave differently. A bottle cap that reads 14–15 in Multi-IQ can jump to the high 20s at 10 kHz single frequency. That shift is diagnostic, not a defect: it is how experienced Equinox users separate crown caps from copper.
Community charts for the Nokta Simplex commonly place ferrous targets at 0–15, nickels around 20–25, and silver and brass from 43–99. But those ranges vary with soil, depth, and firmware. The same chart is a starting point, not a rulebook. The reliable method is to build a personal ID map for your detector by air-testing known targets—a nickel, a silver dime, a pull tab, a rusty nail—and noting where they fall on your machine, in your soil, at the depths you hunt.
This is also why chasing the highest number is a trap. Iron often produces intermittent high spikes that look like a good conductor. A bent nail can flash 80–90 one sweep and 10 the next. A coin rarely dips from high to iron without reason. Repeatable mid-range tones, especially with symmetrical audio from multiple angles, matter more than a single high digit.
The Discrimination Toolkit: Notch, Iron Audio, Iron Bias, Iron Filter
Modern detectors give you four distinct tools that are often confused as one: notch discrimination, iron audio, iron bias, and iron filter.
Notch discrimination rejects specific conductivity bands while accepting targets above and below them. On the Garrett ACE series, the lower bar has 12 segments; you can blank out the pull-tab zone without losing nickels. On the Nokta Simplex, 20 notch boxes each cover 5 IDs—01–05, 06–10, and so on—so you can reject the 40–50 band while still hearing 35 and 55. On the XP Deus II, Multi-Notch lets you define up to three separate rejection windows, such as foil, crown cap, and zinc penny ranges, all at once.
Iron Audio (Garrett AT Pro and AT Max) does not reject iron more aggressively. Instead, when enabled, discriminated iron still produces a low-tone grunt. That reveals bottle caps and complex iron that would otherwise be silent or falsely mimic a high conductor. The low grunt tells you the target is probably junk even when the ID number flashes high. It is the fastest way to learn what a bottle cap sounds like before you dig fifty of them.
Iron Bias (Minelab Equinox) adjusts how aggressively the detector classifies mixed ferrous/non-ferrous responses as iron. The FE and F2 settings range 0–9. At low values, the detector lets more mixed signals through as non-ferrous—good for unmasking coins among nails, at the cost of digging more rusty bits. At high values, it kills the iron but can misclassify borderline non-ferrous targets as ferrous. The F2 profile is tuned for crown caps and modern trash; FE is broader.
Iron Filter (Nokta Legend) works similarly to Iron Bias but with an extra layer. The Iron Filter runs 0–9 in Park, Field, and Gold Field modes and 1–9 in Beach, with a default of 8. The Stability setting, 1–5, fine-tunes how the Iron Filter behaves when IF is below 8. Lower IF plus lower Stability improves the chance of hearing small or borderline non-ferrous targets in dense iron, but it also increases iron falsing. In clean ground, higher IF keeps the audio calm.
Garrett ACE Series: Learning Discrimination on a Budget
The Garrett ACE 300 is the most approachable entry point for learning notch discrimination. It offers a true 0–99 digital Target ID, which many budget machines lack, plus a 12-segment notch bar controlled by DISCRIM (+/–) and Accept/Reject. The preset modes—Zero Disc, Jewelry, Relics, Coins, and Custom—give you different starting patterns. Custom mode saves your notch changes, so you can build a setup for a specific park and return to it.
The ACE 300's digital scale gives repeatable coin IDs in clean ground but becomes jumpier in mineralized soil and trashy parks, where the detector's single-frequency operation struggles with modern alloys. That is why the standard advice is to start in Coins or Jewelry mode, not Zero Disc. A light notch that removes only the lowest foil segments keeps small gold and odd relics audible while silencing the most common trash.
The ACE series is not equipped with Iron Audio or a dedicated iron discrimination range. Its discrimination is purely notch-based, which means iron below a certain conductivity is either rejected or accepted, not differentiated by tone. That is fine for parks and tot lots, but it limits unmasking in dense iron. If you hunt old home sites or relic fields, the ACE will leave more masked non-ferrous targets in the ground than an AT Pro or Equinox. Still, for learning how numbers map to dig decisions, the ACE 300 is hard to beat.
Garrett AT Pro and AT Max: Iron Audio and High-Resolution Iron Disc
The Garrett AT Pro adds the missing piece for relic and iron-heavy sites: a 40-point High-Resolution Iron Discrimination range from 0–39, controlled by IRON DISC. Instead of a single iron cutoff, you can fine-tune exactly where iron gets rejected while leaving non-ferrous targets above that point fully audible. The AT Max takes this further with up to 44 iron segments and True All-Metal Iron Audio.
Iron Audio is the defining feature here. When enabled, rejected iron still produces a low-tone grunt. That grunt reveals bottle caps and complex iron that produce intermittent high spikes. The proportional audio in Pro Mode and the Tone Roll Audio let you judge size and depth: shallow or large targets sound louder and "fuller," while bottle caps produce a broken or grunty high tone instead of the clean, sharp response of a coin.
The AT Pro's workflow for a nail-infested homesite is to set a moderate IRON DISC around 20–25, keep Iron Audio on, and listen for the difference between a cap's broken high and a coin's clean repeatable hit. In cleaner relic fields, lowering IRON DISC and opening more of the scale reduces masking of non-ferrous adjacent to iron. The AT Max pushes that further: all-metal Iron Audio lets you run true all-metal and still hear iron grunts, making it possible to pick masked conductors out of dense iron.
Both machines reward smaller coils and slower sweeps when discrimination is low and iron is heavy. Fast sweep speeds compress the audio and make the grunt less readable. If you are serious about unmasking silver in old parks, the AT Max's finer iron control and Z-Lynk wireless audio are genuine advantages, but the AT Pro remains a solid mid-range workhorse.
Check current price on Amazon — Garrett AT Pro
Check current price on Amazon — Garrett AT Max
Minelab Equinox 700: Multi-IQ, Iron Bias, and Crown Caps
The Minelab Equinox 700 represents the multi-frequency side of discrimination. Its Multi-IQ engine transmits at multiple frequencies simultaneously and uses the differences to stabilize target ID. The 119-segment Target ID system on the 700 gives much finer discrimination than earlier 50-segment Equinox models. The older −9 to 40 scale still applies conceptually: −9 to 0 is ferrous, 1 to 40 is non-ferrous. The 700 splits that range into more increments, so a copper coin that reads 21 on the older scale is easier to separate from a nearby lead fragment.
The critical setting on the Equinox is Iron Bias, with FE and F2 profiles each ranging 0–9. Low Iron Bias (FE/F2 near 0–2) lets more mixed ferrous/non-ferrous responses through as non-ferrous. That is the correct starting point when hunting non-ferrous targets among nails—old sites, house tear-outs, cellar holes. You will dig more iron, but you will unmask coins and buttons that high Iron Bias would misclassify as iron. High Iron Bias reduces diggable iron at modern trashy sites, but it also risks suppressing borderline non-ferrous targets.
The Recovery Speed control interacts with Iron Bias. Higher recovery speeds improve target separation in trash but reduce depth and can make iron falses sharper. Lower recovery speeds go deeper in clean ground but let adjacent targets blend. For bottle caps, the classic Equinox test is to check a target in both Multi-IQ and a single frequency like 10 kHz. A crown cap that reads 14–15 in Multi-IQ will often jump to the high 20s at 10 kHz. A copper coin stays around 21. That shift is one of the most reliable in-the-field cap checks available.
The Equinox 700's Park, Field, Beach, and Gold modes each apply different default discrimination and audio profiles. Park is tuned for modern trash with tighter iron rejection; Field opens up the ferrous range for relics; Beach handles salt and black sand without falsing; Gold uses a different audio profile for small gold. Understanding those mode defaults is half the battle before you touch Iron Bias.
XP Deus II: Audio-First Discrimination and the X-Y Screen
The XP Deus II takes a different path: it is an audio-first detector. Its Fast Multi-Frequency platform allows discrimination from −6.4 to 99, but experienced users rarely run high numeric discrimination. Instead, they rely on multi-tone audio—2, 3, 4, 5 tones, full tones, or pitch modes—to interpret target character without hard-rejecting broad ranges.
Full tones and pitch modes are the heart of Deus II discrimination. In full tones, the audio pitch rises proportionally with conductivity, so you hear a complete tonal shape of the target rather than a single on/off. A coin gives a clean, stable high tone; a bottle cap gives a broken or hollow high with a sharp low edge; a gold ring often gives a repeatable mid tone that fluctuates less than foil. Pitch mode emphasizes signal strength rather than conductivity, useful for deep targets where conductivity ID becomes unreliable.
The X-Y oscilloscope screen is the other major discrimination tool. It displays the target's phase response as a trace pattern on a two-axis graph. Ferrous items, cans, and crown caps produce distinctive trace shapes that differ from coins and lead. With practice, a quick glance at the X-Y trace is faster than waiting for a stable numeric ID, especially on deep or masked targets where numbers bounce.
For trashy sites, the Deus II's Multi-Notch allows up to three rejection windows—N1, N2, N3—so you can kill the pull-tab band, the crown cap zone, and the zinc penny range without touching anything above or below. The advanced tone breaks and ground/iron threshold controls let you partition the audio exactly where you want the low grunt to stop and the mid tone to begin.
The real strength of the Deus II is its fast recovery combined with low discrimination. In nail-infested ground, running low disc and high reactivity with a small coil reduces masking far more effectively than heavy notching. The detector reacquires quickly between adjacent targets, so you can sweep through iron and still hear the coin tucked next to a nail.
Nokta Legend and Simplex: Iron Filter, Stability, and Notch Boxes
Nokta gives you two strong discrimination systems across its mid-range and budget lines: the Legend with Iron Filter and Stability, and the Simplex with 20 notch boxes.
The Nokta Legend is a simultaneous multi-frequency detector with selectable 4, 10, 15, 20, and 40 kHz operation. Its default discrimination rejects IDs 1–11 and accepts 12–60. Custom notch patterns can accept or reject individual IDs, either manually by moving a cursor under the scale or automatically by swinging over a target and notching that ID on the fly. The automatic notch is convenient, but it can accidentally kill future targets that share the same ID group. Manual notch is safer if you want to preserve small gold.
The Legend's Iron Filter behaves like a cross between Minelab Iron Bias and Garrett Iron Audio. Ranging 0–9, with a default of 8, it controls how aggressively ferrous is rejected. The Stability setting, 1–5, fine-tunes the Iron Filter when IF is below 8. At high IF/St values, you reduce iron falsing and quiet down shotgun shells and other metallic trash. At lower IF/St, you increase the chance of hearing tiny or borderline non-ferrous targets among iron—at the cost of more iron digs. Start with the default IF 8, then back off in dense relic iron or when chasing small gold, especially in Field and Gold Field modes.
The Nokta Simplex is the budget entry with real notch discrimination. Its two-digit 01–99 scale and 20 notch boxes—each covering 5 IDs—allow any combination of accepted and rejected bands. Park, Field, Beach, and All Metal modes come with different preset notch and iron-off behavior. Some Park modes auto-notch 0–15 IDs to cut iron and noise, which is a useful starting point. You can also notch automatically by swinging over an unwanted target and confirming, but the same caution applies: auto-notch a pull tab, and you may silence a gold ring that shares the same 5-ID box.
For jewelry and beach hunting, keep the mid-range boxes open. Gold rings can span 10–60 IDs on the Simplex scale, overlapping heavily with foil, pull tabs, and zinc. Blacking out everything below a certain number to kill trash also kills most gold. The better approach is the same one you use on any machine: reduce notch to only the worst trash, lower recovery speed when you can, and listen for repeatable mid tones.
Check current price on Amazon — Nokta Legend
Check current price on Amazon — Nokta Simplex Lite
Pinpointers: What Discrimination Means in the Hole
Pinpointers do not discriminate the way the main detector does, but three models bundle ferrous or tone features that speed up in-hole decisions.
The Garrett Pro-Pointer AT detects all metals with no true conductivity-based discrimination. It operates at 11.5 kHz, offers three sensitivity settings, and has two modes: audio+vibrate or vibrate-only. Its Fast Retune button narrows the detection field or tunes out saltwater, wet sand, and mineralized ground—reducing false responses without rejecting ferrous. Do not expect it to tell iron from silver; once you open the plug, it beeps on both. But the retune feature helps you lock onto the target's edge and ignore mineralized soil noise.
The Minelab PRO-FIND 35 adds Ferrous Tone ID, giving distinct audio and vibration responses for ferrous versus non-ferrous targets. It is not a full target-ID system—it is a coarse ferrous flag—but in mixed iron and modern trash holes, that difference is valuable. When you have already dug a rusty nail and the pinpointer shows a ferrous tone on the next fragment, you know to keep moving. The PRO-FIND 35 is waterproof to 3 meters, offers 5 sensitivity levels, and includes DIF technology that disconnects its coil field when off to avoid interfering with nearby detectors.
The XP MI-6 is aimed at XP ecosystem users. It links wirelessly to the Deus II, Deus, and ORX, letting you adjust sensitivity, tones, pitch, and volume directly from the detector's remote. Audio modes include Pitch and Pulse, with Pulse recommended for noisy environments. Like XP's main detectors, the MI-6 emphasizes tone and sensitivity rather than a hard ferrous/non-ferrous ID. Its value is the seamless integration: the pinpointer feels like an extension of the detector's discrimination scheme, not a separate box.
The right pinpointer depends on your main detector. If you run an Equinox or a Nokta, the PRO-FIND 35's ferrous tone ID is a genuine upgrade. If you use XP, the MI-6 is the obvious choice. If you want maximum simplicity and reliability at depth, the Pro-Pointer AT remains a solid all-metal pinpointer.
Check current price on Amazon — Garrett Pro-Pointer AT
Check current price on Amazon — Minelab PRO-FIND 35
Check current price on Amazon — XP MI-6
Masking, Recovery Speed, and the Depth Trade-Off
The most important concept in discrimination is masking. When a good non-ferrous target sits next to iron or trash, raising discrimination can cause the detector to see the iron as the dominant response and suppress the coin entirely. This happens because the detector's circuitry averages the phase shift of both targets, and the lower-conductive iron can pull the response below the discrimination threshold. The good target is still there—it is just masked.
High discrimination, high iron bias, or high iron filter all increase the risk of masking. That is why experienced detectorists run low discrimination in old, nail-infested sites. A lower threshold means the mixed signal gets through, and the audio—grunt plus high tone—tells you there are two targets or a complex one. You then decide by digging. Small coils and slow sweep speeds improve unmasking further, because the detector sees fewer targets at once and the audio has time to separate.
Recovery speed is a separate control that is often confused with discrimination. It governs how quickly the detector resets between adjacent targets. High recovery speed improves target separation in trashy sites: two coins 2 inches apart are reported as two signals, not one blended response. But high recovery speed reduces depth, because the detector spends less time integrating each target's response. Low recovery speed goes deeper in clean ground but blends adjacent targets.
The trade-off is directional, not numeric. In a trashy park, run higher recovery speed and moderate discrimination to cut through the junk. In a clean field, lower recovery speed and lower discrimination will find deeper targets. The interaction with discrimination also matters: raising discrimination while keeping recovery speed high can cause the detector to skip brief high-conductivity spikes from masked coins, increasing the masking effect.
Practical Discrimination Settings by Site
Different sites demand different discrimination profiles. Here are the working baselines that come out of community practice, adapted to each detector family.
Modern parks and tot lots. These are trash-heavy but shallow. Start in the detector's Park mode: a Garrett ACE in Coins or Jewelry mode, an Equinox in Park 1, a Legend in Park, a Simplex in Park. Reject only the lowest foil and iron ranges. Keep recovery speed moderate to high. Expect lots of foil and pull tabs; do not black out the entire mid-range or you will miss small gold.
Old homesites and cellar holes. Iron is dense and old targets are deep. Use lower discrimination and Iron Bias/Iron Filter. On an Equinox, set FE or F2 around 0–2. On a Legend, lower IF to 5–6 with Stability 3–4. On a Deus II, keep discrimination low and use full tones or the X-Y screen. On a Garrett AT Pro or AT Max, run IRON DISC around 20–25 with Iron Audio on. Sweep slowly.
Beaches. The main enemy is saltwater and black sand. Use the detector's Beach mode, which is tuned to handle mineralization and salt. Discrimination can stay moderate because deep beach targets are usually recent losses, not masked relics. If you use a pinpointer, the Pro-Pointer AT's Fast Retune helps in wet sand; the PRO-FIND 35 and MI-6 are waterproof for shallow water work.
Relic fields and gold ground. For relics, open the discrimination as much as you can tolerate. Run all-metal or minimal disc, and rely on audio nuances. For small gold, use Gold Field mode on the Nokta Legend and Gold mode on the Equinox, both of which use different audio profiles. Lower Iron Filter or Iron Bias to let borderline non-ferrous signals through. In dense iron, always use a small coil and slow sweep.
Verifying your settings in the field. Before trusting a discrimination pattern, run a quick in-ground test with a known nickel, a pull tab, a rusty nail, and a silver dime. Bury them at the depth you normally hunt, sweep from multiple angles, and note where each one hits on your detector's scale. This takes five minutes and gives you a detector-specific ID map. No generic chart from the internet can replace it.
Which Detector Family Fits Your Hunting?
The best discrimination system is the one that matches how and where you detect.
If you are learning or on a budget: the Garrett ACE 300 and Nokta Simplex both give you real notch discrimination and a digital ID scale. The Simplex adds more notch granularity with 20 boxes, while the ACE has the classic 12-segment bar and a clean 0–99 display. Both are strong choices for parks and tot lots.
If you hunt old sites and need iron audio: the Garrett AT Pro and AT Max are the direct answer. The AT Max's 44 iron segments and True All-Metal Iron Audio make it possible to run all-metal and still hear iron grunts, which is exactly what you want for unmasking silver in dense iron. The AT Pro offers the same capability at a lower material cost.
If you want multi-frequency stability and crown cap control: the Minelab Equinox 700 is the most complete discrimination package. Multi-IQ keeps non-ferrous IDs stable, Iron Bias handles modern trash, and the 119-segment scale separates close targets. It is the strongest all-around pick for mixed parks, fields, and beaches.
If you are audio-driven and want maximum unmasking: the XP Deus II is the detector you grow into. Its full tones, pitch modes, X-Y screen, and ultra-fast recovery let you run very low discrimination in the worst iron. You trade a steep learning curve for the ability to hear what others miss.
If you want a strong mid-range iron control system: the Nokta Legend offers Iron Filter and Stability at a mid-range level. Its default iron rejection is good out of the box, and the auto-notch feature is fast. The Legend is a solid bridge between the Simplex and the high-end multi-frequency machines.
Frequently Asked Questions
Q: What does the number on my metal detector mean?
The number is a target ID value that represents the conductivity and phase shift of the object under the coil. On a 0–99 scale, low numbers are usually iron and foil, mid numbers are thin or low-conductivity non-ferrous like nickels and small gold, and high numbers are silver, copper, and brass. But the exact number for a given object varies by detector brand, mode, depth, and soil.
Q: Is notch discrimination only for beginners?
No. Notch discrimination is a surgical tool for rejecting a specific conductivity band—such as the pull-tab range—without losing targets above or below it. Beginners use broad notch patterns to quiet trash, but advanced detectorists use narrow multi-notch windows on machines like the XP Deus II to kill only crown caps or zinc pennies while keeping small gold and odd relics audible.
Q: Does raising discrimination always cost depth?
Not always, and not in a simple linear way. Discrimination filters targets by conductivity, not depth. But high discrimination or high iron bias increases the risk of masking, where a good target next to iron is suppressed. The actual depth loss depends on soil, target size, recovery speed, and coil size. The safe rule: in clean ground, moderate to low discrimination costs little depth; in dense iron, high discrimination costs real depth through masking.
Q: What is the difference between Iron Bias and Iron Filter?
They serve the same purpose but come from different manufacturers. Minelab Iron Bias on the Equinox adjusts how aggressively mixed ferrous/non-ferrous responses are classified as iron, using FE and F2 profiles from 0–9. Nokta Iron Filter on the Legend works similarly, also 0–9, with an additional Stability setting (1–5) that fine-tunes iron rejection when the filter is below 8. Both are trade-offs between digging iron and missing masked non-ferrous.
Q: Why do bottle caps sometimes read like coins?
Bottle caps have a shape and metal composition that produces a high-conductivity spike on many detectors. On the Minelab Equinox, a crown cap often reads 14–15 in Multi-IQ but jumps to the high 20s at 10 kHz single frequency. On Garrett machines, Iron Audio reveals the cap with a low grunt and a broken high tone. Learning the audio character of a cap on your specific detector is more reliable than trusting one ID number.
Q: Should I use a pinpointer with ferrous tone ID?
If you hunt old iron-infested sites, yes. The Minelab PRO-FIND 35 gives a distinct ferrous versus non-ferrous tone that speeds up in-hole decisions. It is not a full discrimination system—it is a coarse ferrous flag—but after you dig a rusty nail, a ferrous tone on the next fragment tells you to move on. On clean modern parks, a simple all-metal pinpointer like the Garrett Pro-Pointer AT is often enough.
Conclusion
Discrimination and target ID are estimates based on conductivity and phase shift, not object names. The number on the screen only becomes useful when you know your detector's scale, your soil, and what a repeatable signal sounds like. The central skill in metal detecting is not memorizing charts—it is learning to read the whole system: number, tone, iron response, depth, and recovery speed together.
The major brand families solve the same problem differently. Garrett gives you notch segments and audible iron. Minelab gives you Multi-IQ and Iron Bias. XP gives you audio and the X-Y screen. Nokta gives you Iron Filter, Stability, and notch boxes. None is objectively better in all ground; each is better in specific conditions.
Start with the detector you have, run the mode that matches your site, and keep discrimination lighter than you think you need. Test known targets in your own ground, write down the numbers, and trust repeatability over a high spike. When the audio grunts instead of singing, and the number jumps instead of sticking, that is the detector telling you to slow down, open the disc, and dig.
If you are ready to upgrade your control, the detectors covered here are all solid places to look. Use the links above to compare current pricing on Amazon, and choose the one whose discrimination system fits the ground you walk.
