VLF metal detector buying advice

[Skippy]

Quote:"I have seen a .. demonstration of the T2, and it looks like it doesn't discriminate beyond a certain depth"
All VLF detectors do this. It's not hard to determine if a target is present, but it takes a stronger signal (ie. shallower target) in order to get enough information to reliable perform discrimination. So, for example a coin will give good ID to 8 inches, jumpy ID to 10 inches, will read as iron to 12 inches, and won't trigger at all beyond that. User skill comes into it - a jumpy 9 inch signal can be turned into a steady 9 inch signal, an 11 inch iron-tone can be turned into a jumpy non-iron tone. etc. They generally report the weakest signals as iron because the ground itself is effectively a sheet of micro-iron.

[soverey]

Quote:"I have seen a .. demonstration of the T2, and it looks like it doesn't discriminate beyond a certain depth"
All VLF detectors do this. It's not hard to determine if a target is present, but it takes a stronger signal (ie. shallower target) in order to get enough information to reliable perform discrimination. So, for example a coin will give good ID to 8 inches, jumpy ID to 10 inches, will read as iron to 12 inches, and won't trigger at all beyond that. User skill comes into it - a jumpy 9 inch signal can be turned into a steady 9 inch signal, an 11 inch iron-tone can be turned into a jumpy non-iron tone. etc. They generally report the weakest signals as iron because the ground itself is effectively a sheet of micro-iron.

If you watch the video it seems it doesn't discriminate a silver coin beyond 10-13 cm (that about 5- 5.5 inches).....although it seems it can detect it fairly well at higher depths.

[Skippy]

My computer is too rubbish, I can't watch the video, I would have to take some headphones down to my local library and watch it there. However, the "video title" describes this coin as a small 13th century silver hammered. I am familar with these coins, and they are not easy to find. They are light (1.0 - 1.3 grams typically), they have a high "corner frequency" (break frequency, -3dB freq etc) typically 15 - 20 KHz, meaning machines that run at these sort of freqs find them best. But high freq machines pick up more ground signal, which limits their depth. These coins are often cracked, bent, incomplete, heavily corroded as well. So finding them at depths beyond 7 inches is rare, though not impossible. It depends on how weak or strong the ground signal is. And how flat-on they are buried, and whether they are long-buried or from ploughed fields that get disturbed annually. etc etc. And many other factors. For example - hammered coins are typically found in land that has been used extensively for centuries. Thus it has a LOT of other junk, especially iron, in it. These other items can mask/hide the desireable targets easily.
The T2 / F75 machines are competent at finding targets like hammered coins. But only in rare circumstances will you dig one from 9 inches.
The same applies to XP GMP / Deus, they may do a little better than the T2/F75 when run at 18 KHz, but don't fall for all the "hammy hoover" hype.
I think your problem is your understanding of the term "coin-sized targets". This very vague description is often used (by US manufacturers) to mean modern milled coinage of medium size. Examples would be US 5 cent "Nickel", 1 cent, 25 c "Quarter", or U.K 1 Pence, 20 Pence, Eurozone 20, 50 EuroCents. etc. Medieval hammered coins are absolutely not "coin-sized targets". They may be 17mm diameter, but that's it. They are 0.3mm thick, with all the other previous mentioned problem characteristics.

[Davor]

If you watch the video it seems it doesn't discriminate a silver coin beyond 10-13 cm (that about 5- 5.5 inches).....although it seems it can detect it fairly well at higher depths.

I'd say this is a good thing. Let me try to explain...
In VLF sound level is extracted from "all metal" channel, simply because it is not affected by ground. When you ground balance your rig, you are actually notching out ground response from the "all metal" channel.
Discrimination is something else. It is extracted from a motion channel at angle against the "all metal", and it has poor response for low conductivity and thin (e.g. hammered) metal objects. All traditional detectors use this channel to gate the "all metal" channel, and therefore such detectors have poor response for thin and poor conductivity objects. This detector is not gating the "all metal" audio, but instead it plays with tonal properties, and you get some response - wrongly VDIed, but response nonetheless.
So, all things not being equal, I'd say that having some indication is better than none. Such targets as in a video you'd probably miss altogether with a traditional VLF.

[Koala]

My IDX 6 KHz machine will pick up tiny hammered at good depth but not if they are on their edge. Don't think frequency of machine makes such a big difference as the marketing people will have you believe. The quality of the rest of the detector and coil/coil size makes more of a difference

The Golden Mask 1+ at 18 GHz against my 6 KHz are almost identical on a Henry V cut half. My IDX was slightly deeper but the coil was slightly bigger 7" vs 8" so not totally fair test. The same happens with most of the online tests I have seen. Either the test are bias as they sell a brand of detector. The tests are done by someone who does not know how to get the best from that model or the coils are different. Its like comparing Apples to Pears.

There is no best detector and everyone will have there own opinion. But most mid rang detectors have very similar performance if set up properly.

[Skippy]

The F75 can, I believe trigger off a combination of resistive/reactive channels, this is the JE (jewelry) mode, it has enhanced sensitivty to lower conductors. Though if you run in DE (default) mode at very low disc settings (1 to 4) it seems to do the same thing. I normally run my F75 at Disc=1 in DE mode; you hear everything, tone ID, with high sensitivity. If you're doing what Soverey is doing, looking for isolated targets, it would be best. You would always get a "hit" of some kind, even if iron-tone. Then you can investigate further and determine if it is actually iron, or a weak non-iron, etc, and use your judgement to determine whether it's a "dig" or not.
The thing about high-end machines like the T2 (and others) is that they WILL give you some indication on targets that other machines just plain won't see. User skill then turns these into diggable targets.

[golfnut]

the soverign or explorer are good

you ask for 12 on a coin.. this is 3030 territory but out of yr budget

[Skippy]

It depends how important your wishlist is, and what exactly you're looking for / hoping to find. And what the nature of your soil is...
As suggested by Golfnut, depth monsters on milled copper/silver coins are the Minelab FBS/BBS dual-frequency machines, so you would need to consider previously-owned Explorers, E-Tracs.....but they are pretty heavy lumps, not ideal for dragging up mountains and swinging all day. And they generally need to be swung slowly, not good if you're trying to cover lots of ground quickly.

[soverey]

I own a minelab safari, and is not what I would call a depth monster, I tested it with different targets under compacted soil. Discrimination is good, it seems that it is designed to detect only to the depth it can accurately discriminate. The T2 looks more sensitive, and discrimination probably a little less accurate, but only slightly.

[Skippy]

I don't see many people on the forums using Safari's, I often wondered if they were lacking in performance. Maybe their lack of adjustments mean they just won't go as deep as their siblings. It would've been sensible to tell us that you had the Safari in your first post.
Maybe you've seen this depth test, but I'll post it anyway:
http://www.staffsmetaldetectors.co.uk/depth_test.htm
People who like the T2 and it's cousins generally rate it for its all-round performance. It finds high-conductor coins well, it finds low-conductors like gold rings, medieval coins well, it's pretty good depth-wise (considering it's single-frequency) and it finds stuff in busy ground with lots of other junk there. There's also a decent choice of coils for it, it runs forever on the batteries, it's acceptably light.