The basics: why frequency matters so much
Most hobby metal detectors work on the VLF principle (Very Low Frequency, induction balance). The transmit coil generates an alternating magnetic field. When this field hits metal, eddy currents are induced in the object, which in turn build up a weak opposing field. The receive coil registers this signal, and the electronics derive the conductivity from the time shift (phase), which you see as the target ID on the display.
How strongly and how clearly an object responds depends on the frequency used. Put simply:
Low (approx. 4–8 kHz)
Strong on large, highly conductive objects such as large silver coins, copper or bronze. Small and thin objects tend to get lost.
Medium (approx. 10–20 kHz)
The classic all-round range for coins, jewellery and relics with balanced sensitivity.
High (approx. 25–45 kHz)
Very sensitive to small and low-conductivity objects such as thin hammered coins, fine gold jewellery or gold nuggets. However, it also reacts more strongly to mineralised ground.
A single-frequency detector therefore always has to settle for a compromise. This is exactly where multi-frequency technology comes in.
What exactly does “multi-frequency” mean?
The term is not always used consistently in the trade. It is important to distinguish between two designs:
Simultaneous multi-frequency
Several frequencies are transmitted and evaluated at the same time. The electronics compare the responses with each other and gain additional information about the object and the ground. Examples: Minelab Multi-IQ / Multi-IQ+, XP FMF®, Nokta Multi, Garrett Multi-Flex in Multi mode.
Selectable frequencies
The detector offers several frequencies to choose from, but always works on only one frequency at a time. This is practical and flexible, but technically not simultaneous multi-frequency.
Many modern detectors can do both: one or more simultaneous multi-frequency programs and additional selectable single frequencies for special tasks.
Multi-frequency is not an XP invention: a look at the history of the technology
XP is by no means the only manufacturer to rely on simultaneous multi-frequency technology. Minelab has been researching in this direction since the early 1990s, and Nokta and Garrett have since developed their own systems too.
- Early 1990s
Minelab Sovereign with BBS (Broad Band Spectrum): one of the first multi-frequency detectors for hobbyists. According to the Minelab manual, the BBS circuit of the later Sovereign Elite transmits 17 frequencies simultaneously, spread over a range of approx. 1.5 to 25.5 kHz.
- 2000s
FBS (Full Band Spectrum) in the Explorer and E-TRAC series, later FBS 2 in the CTX 3030. These detectors provided a lot of information, but were comparatively heavy, expensive and rather slow in signal processing.
- 2017/2018
Minelab EQUINOX with Multi-IQ: a technology developed from scratch. It combines simultaneous multi-frequency with a much faster recovery time than BBS/FBS and made multi-frequency popular in the mid-range.
- 2020
Garrett ACE APEX with Multi-Flex and Minelab VANQUISH bring simultaneous multi-frequency to the entry-level and mid-range classes as well.
- 2021
XP DEUS II with FMF® (Fast Multi Frequency): the first fully wireless multi-frequency detector, with multi-frequency programs or, alternatively, 49 single frequencies from 4 to 45 kHz. In the same period, Nokta The Legend appears with three multi-frequency modes.
- 2022/2023
Minelab MANTICORE with Multi-IQ+: the further developed generation with, according to the manufacturer, around 50% more transmit power than the EQUINOX and a wider frequency spectrum. The EQUINOX 700 and 900 follow.
- 2026
Nokta The Legend 2 as the successor with multi-frequency and single frequencies from 4 to 40 kHz.
Multi-IQ and Multi-IQ+: what is the difference?
At Minelab, Multi-IQ stands for simultaneous multi-frequency with in-phase and phase-shifted evaluation (in-phase and quadrature). Compared with the older BBS/FBS systems, Multi-IQ uses a different set of base frequencies, is more sensitive to targets that favour high frequencies and responds much faster thanks to modern processors.
Multi-IQ+ builds on this: Minelab states a higher transmit power over a wider frequency spectrum as well as more powerful signal processing. In practice, this shows above all in depth: while a single frequency often delivers inaccurate or ambiguous target IDs with increasing depth, the target ID with Multi-IQ+ remains largely stable even for deeper objects. However, Minelab does not disclose in detail exactly how the two generations differ internally.
Same basic principle, own implementation: the systems at a glance
At their core, all manufacturers pursue the same idea: using several frequencies at the same time to detect small and large, low and highly conductive objects more reliably than with a single fixed frequency. However, the implementation differs.
| Manufacturer | Technology | Example models | Selectable single frequencies |
|---|---|---|---|
| XP | FMF® (Fast Multi Frequency) | XP DEUS II | 49 frequencies from 4 to 45 kHz |
| Minelab | Multi-IQ | EQUINOX 700 / 900, VANQUISH | depending on the model, e.g. 4, 5, 10, 15, 20, 40 kHz (EQUINOX 900) |
| Minelab | Multi-IQ+ | MANTICORE | 5, 10, 15, 20, 40 kHz |
| Nokta | Simultaneous multi-frequency (3 multi modes) | The Legend, The Legend 2 | 4, 10, 15, 20, 40 kHz (Legend 2) |
| Garrett | Multi-Flex | ACE APEX | 5, 10, 15, 20 kHz plus Multi and Multi-Salt |
Tip: on a smartphone, you can swipe the table sideways. Data according to manufacturer information, as of October 2026.
Does a multi-frequency detector really find deeper?
There is no blanket answer to that. Under ideal conditions, for example with a large silver object in neutral ground, a suitably chosen single frequency can certainly reach similar depths. The strength of multi-frequency lies elsewhere: the detector recognises different targets more reliably under changing ground conditions. Whether small coins, fine jewellery or difficult ground: multi-frequency technology often delivers more stable signals and more usable information.
That is exactly why multi-frequency detectors such as the XP DEUS II and the Minelab EQUINOX series have established themselves as the first choice for many detectorists. Ultimately, what counts is not just how deep a detector searches, but above all what it can still reliably identify at that depth.
The 5 most important practical advantages of multi-frequency
1. Finding small coins and low-conductivity objects more easily
Tiny items, thin silver coins or fine gold objects often give only weak signals. In mineralised ground in particular, single-frequency detectors reach their limits here; low frequencies such as 4 or 7 kHz sometimes miss such objects even at shallow depths. Multi-frequency combines high and low components and detects small targets much more reliably.
Your advantage: You will walk over thin silver coins, fine jewellery and other tiny items less often.
2. Identifying large metal masses and coin hoards more reliably
Conversely, low frequencies pick up large masses or accumulations of coins that a high frequency (about 20 to 40 kHz and above) detects poorly, discriminates incorrectly or, depending on their position, even interprets as iron. A multi-frequency detector processes high and low frequencies at the same time.
Your advantage: Whether a single coin or a larger hoard: the probability that you will assess the signal correctly increases.
3. More stability in mineralised ground and on the beach
Electrically conductive ground such as saltwater beaches or heavily mineralised fields easily throws single-frequency detectors off balance: false signals, unsteady tones, jumping target IDs. As ground and metal react differently to different frequencies, a multi-frequency detector can cancel out the ground signal more precisely. In damp ground, single-frequency detectors also often show “halos” (conductivity fluctuations caused by soil moisture). The XP DEUS II removes these, for example, in the GENERAL and RELIC modes by subtracting the soil moisture.
Your advantage: Smoother running and better detection of genuine targets on difficult ground.
4. Stable target IDs and clear tones at depth
Hearing a signal is one thing, assessing it correctly is another. With increasing depth, target IDs become less accurate on many detectors and tones begin to fluctuate. Multi-frequency often delivers more stable target IDs even with weak signals, so that you can better assess a target before you start digging.
Your advantage: Dig up less junk, have more time for genuinely interesting finds.
5. Masking out bottle caps and sources of interference
Thanks to better material identification, XP and Minelab detectors can identify and mask out ferrous bottle caps more reliably (bottle cap filter). Conductive stones such as coke or coal and ground variations such as wet clay, which often cause interference and halos, can also be filtered out specifically using notch – on the XP DEUS II, for example, in the target ID range 23 to 25.
Your advantage: Fewer bottle caps on heavily frequented areas such as parks, fairgrounds or bathing spots.
Bonus: one detector for (almost) every terrain
Where you used to need a field detector, a beach detector and a gold detector, a modern multi-frequency detector covers many areas with one device: fields, woodland, parks, beaches and shallow water. Single frequencies are also available for special tasks.
Your advantage: More flexibility and less equipment to carry.
To be honest: where multi-frequency reaches its limits
Multi-frequency is not a miracle cure. From more than 30 years of our own detecting experience, we can tell you: single frequencies still have their place.
- Electromagnetic interference: Near power lines, electric fences or radio masts, a single, suitably chosen frequency often runs more quietly.
- Special tasks: For gold nuggets or very small hammered coins, high single frequencies often have the edge; for large silver coins in neutral ground, low ones do.
- Battery life: Depending on the detector, power consumption is somewhat higher in multi-frequency mode.
- Setup and experience: A well set-up detector in experienced hands beats any technology. A detector only shows its best performance once you know it.
Conclusion: multi-frequency above all means more information
The question “Does the XP DEUS II find deeper?” cannot be answered in general terms. Much more important is this: modern multi-frequency technologies such as XP FMF®, Minelab Multi-IQ / Multi-IQ+, Nokta Multi or Garrett Multi-Flex provide considerably more information about the object and the ground than a classic single-frequency detector. Small objects are detected better, large metal masses are assessed more reliably and difficult ground is compensated more effectively, regardless of which manufacturer you choose.
For you, this means: more stable signals, better digging decisions and ultimately a higher chance of interesting finds.
Frequently asked questions about multi-frequency
What is a multi-frequency metal detector?
A multi-frequency metal detector transmits and receives several frequencies at the same time and evaluates them together. In this way, it combines the strengths of low frequencies (large, highly conductive objects) with those of high frequencies (small, low-conductivity objects) and can cancel out ground effects better.
Is a detector with selectable frequencies also a multi-frequency detector?
No, not in the strict sense. A detector with selectable frequencies always works on only one frequency at a time. Genuine (simultaneous) multi-frequency uses several frequencies at the same moment. Many current detectors offer both.
Does a multi-frequency detector find deeper than a single-frequency detector?
Not automatically. The biggest advantage lies in more stable target IDs, smoother running on mineralised or wet ground and better detection of very different targets. On difficult ground, however, this often leads to more usable depth in practice.
What is the difference between Minelab Multi-IQ and Multi-IQ+?
Multi-IQ+ is the further development of Multi-IQ and is used in the Minelab MANTICORE. According to Minelab, it transmits with around 50% more power than the EQUINOX over a wider frequency spectrum and processes signals more powerfully. In practice, this shows above all in more stable target IDs for deep objects.
Which frequencies does the XP DEUS II use?
The XP DEUS II works with FMF® technology (Fast Multi Frequency) in several multi-frequency programs. Alternatively, 49 single frequencies between 4 and 45 kHz are available.
Is a multi-frequency detector worthwhile for beginners?
Yes, in many cases. Detectors such as the Minelab VANQUISH, Garrett ACE APEX or Nokta The Legend offer multi-frequency at fair prices and are more forgiving of setting errors on changing ground than simple single-frequency detectors. Which model suits you depends on your search area, budget and experience. We will be happy to advise you personally.
Does multi-frequency also work on saltwater beaches?
Yes, that is exactly where it shows its strengths. Wet, salty sand is electrically conductive and severely disrupts single-frequency detectors. Multi-frequency detectors with their own beach mode can cancel out the saltwater signal and run much more smoothly.
