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Rob's write-up is interesting, and points out some of what I remind folks quite often.

January 11, 2020 09:22AM avatar
Thanks for the history lesson on metal detector filters Monte. smiling smiley

I wasn't sure you were on the same reference to 'Frequency' and that's why I covered the basic reference we all used to hear pertaining the a Disc. mode's requirement. Fast-motion being the 4-Filter reference and 2-Filter providing a slow-motion and quick-response performance. Then the 3-Filter models that kind of share the benefits of the other two.

Here's the hyperlink for the article titled How to know what filter setting to use., by Rob Olszta, Find's Treasure Forums, that includes his statement at the bottom "All metal mode uses none of these filters and is therefore a deeper mode."

I've read Rob's write-up before, and it's important to note the particular make/model he's using and referring to because not all detectrors offer the same features. Nor the same filtering controls, either.

You will note Rob Olszta'st article is un-dated, but I presume it could have been published around the same time period as the one below it by Mike Hillis, dated March 21, 2016. So I realize this information, or at least some of it, could now be obsolete.

I wouldn't call it obsolete, just that it is more applicable to that particular model and the reasons he's making adjustments for his site and his needs.

Nevertheless, the statement at the bottom of Olszta's article is what caused me to ask you my question and now I know why AM mode provides more depth of EMF than Disc.. winking smiley

It would have been easy to just refer to Rob's article and then ask about his incorrect statement.

Note that in my reply, I never said the All Metal mode is always going to provide more depth. I didn't say that because I know better. That would be a 'blanket statement' and it isn't correct because not all makes and models confirm that. I learned that long ago.

I often use a Threshold-based All Metal mode, and I'm selective on which make or model I grab for an All Metal mode search. There are pros and cons for each search mode a detector offers, and there are some good reasons why a true, Threshold-based All Metal mode ought to be used for certain hunting needs. For example, the All Metal search mode, a Threshold-based All Metal mode, is very helpful to use if you are trying to cover a wide-open area and want to be alerted to ANY metal target present, and that's because it will respond to both ferrous and non-ferrous objects. Some of those can be missed by a Discriminate mode due to the rejection level used.

Another advantage to searching in a true, Threshold-based All Metal mode is if you listen you can hear the 'near-miss' targets. Those are the ones that are just outside the edge of the search coil and a motion-based Discriminate mode works best if the search coil is swept directly over a target. In All Metal, you can sweep 'close' to a metal object and hear the audio respond to it even though the coil is off to the side a little. Target found in All Metal that often is Target missed in Discrimination.

Note that I said a 'true', Threshold-based All Metal mode. Quite a few detectors have a mode labeled All Metal, but they are just a motion-based Discriminate mode without any rejection. They should be 'accepting' all targets, ferrous and non-ferrous, but they are not working in a true, Threshold-based All Metal mode. Often they work in a silent-search fashion, but some could still have an audio to them, but are not "the real thing." Those All Metal 'accept' Discriminate modes are still a Discriminate mode and are still using 'filters' to process the signal. They just have close to no 'rejection' to deal with.

Since you have a Tesoro Bandido II microMAX I'll use a couple of Tesoro's for example, and point out a few things. Your Bandido II µMAX has an All Metal mode. That is a true, Threshold-based search mode, capable of responding to all metals be them ferrous or non-ferrous. You have to tuning options as well. 'Normal' or Manual Re-Tune so it stays as it is and if there is any drift or change in ground make-up, You, the operator, manually re-tune to the established Threshold audio setting. That toggle also has 'Auto' to select an autt-tune function to maintain any drift or change in ground mineral effect.

Your Bandido series model uses what's called an ED-120 Disc. circuitry. That simply means that most of the lower-conductive targets, mainly the ferrous range and the cut-off at the minimum Disc. setting is close to the ferrous / non-ferrous break point so it might effect detection of some very small, thin, lower-conductive non-ferrous targets. Now, compare this with a Tesoro Compadre or Silver µMAX model.

The Compadre was their lowest-end model and it only has one control knob. That turns the detector On or Off and adjusts the Discriminate mode setting. It uses what is called an ED-180 Disc. circuitry. That means it will 'accept' up to the full 180° detection range which includes ferrous and non-ferrous targets. In other words, it can respond to ALL types of metal targets. When turned on and the control left at the lowest Disc. level, that is the 180° reference point and the control face is labeled 'All Metal', however, it is not a true All Metal mode. It is simply an All Metal 'accept' motion-based Discriminate mode. It can 'accept' all metal, but signals are processed through the filtering Disc. circuitry.

The Silver microMAX model has two knobs and a toggle switch. One control adjusts a Sensitivity level, and the other adjusts the variable Discrimination setting. It uses an ED-120 Disc. circuitry, similar to your Bandido, so when adjusted to the minimum Disc. level it will be close to the ferrous / non-ferrous break-point and 'reject' most ferrous objects. It also has a 2-position toggle switch, labeled Disc. and All Metal. The Disc. position simply functions with the variable Discrimination setting you adjusted. The All Metal position does not use a true, non-discriminating All Metal function. It simply relies on a Discriminate mode setting that is close to the ED-180 point or in other words, is a motion-based Discriminate mode with just about no rejection, therefore 'accepting' ALL metal targets, both ferrous and non-ferrous.

Now, back to the 'depth-of-detection' in different modes.

You can get more depth in the 'Normal' manual re-tune mode than in the Auto-Tune mode because it uses a very fast auto-tune speed. That can tune-out very small or weak-signaling deeper targets that the Normal, non auto-tuning function might still report.

Another difference is that Sensitivity level control you have. It is only functioning in the Disc. mode, not All Metal. The All Metal mode on your Bandido relies on the circuitry designed setting that is at, or close to, a full Sensitivity level .... for the All Metal mode. The newest detector I own and really enjoy is the Nokta / Makro Simplex+ which has four different search mode settings: All Metal, Field, Park and Beach.

I keep the Sensitivity Level set at maximum in all for modes, and in the three Disc. modes I have none of the Discrimination notch segments rejected so I am 'accepting' all ferrous and non-ferrous targets. But my Park mode is different from Field and Beach. It gets less depth than Field or Beach, even though all three have a full Sensitivity level setting. Why? Because the circuitry was designed that way, and for a reason. The Field and Beach modes have almost identical detection depths, and are the deepest modes on my Simplex+.

But, what about the All Metal mode? Isn't it the deepest-detecting mode as Rob suggested in his write-up? No, it isn't. Even at maximum Sensitivity is it a motion-based All Metal mode, and by circuitry design the 'auto-retune' speed is very fast and, due to that, it impedes the functional detection depth. Therefore, both the Field and Beach Discriminate modes are deeper-detecting than the All Metal mode.

As always, I'll hard-copy your reply and file it in my "Monte" folder by current-date-at-the-top, for future reference.
I treasure your replies ! grinning smiley

That's a lot of paperwork to read through, and it might be best to do so over one longer winter season when stuck indoors. Just have pen and notebook handy and make notes of the important things. I usually respond in a post a little lengthy, but that because many readers will be learning, new things to them. Many are newer to this great sport and I therefore emphasize some parts of a reply that they might not be familiar with or quite understand.

BTW, with all the exercise you give your fingers at the keyboard gymnasium, I wouldn't stand a chance in a hand grip contest with you ! LOL

It's only two fingers that get the job done, one on each hand. I never learned to type or 'keyboarding' as they call it today. And with the arthritis and other problems I have and a lot of loss of muscle and strength, no one needs to be concerned about an over-powering grip from this old phart.


"Your EYES ... the only 100% accurate form of Discrimination!"

Stinkwater Wells Trading Post
Metal Detector Evaluations and Product Reviews
monte@ahrps.org ... or ... monte@stinkwaterwells.com
Nokta / Makro: FORS CoRe, FORS Relic, Racer 2 and Simplex + also using Makro and Pulse-Dive Pinpointers
Tesoro: Bandido II µMAX and Silver Sabre µMAX ... White's: modified IDX Pro ... XP: ORX ... Fisher: F44
Headphones: Killer B's 'Hornet' and 'Wasp' -- Detector Pro Gray Ghost XP
Note: Detectors are listed alphabetically by Brand. Models are chosen based on search site conditions.
*** All working well today to make memories for tomorrow. ***
Subject Author Views Posted

VLF Metal Detector Filters

ToddB64 61 January 09, 2020 05:52PM

Todd, an answer about 'Metal Detector Filters' regardless of operating frequency range.

Monte 73 January 10, 2020 11:20AM

Re: Todd, an answer about 'Metal Detector Filters' regardless of operating frequency range.

ToddB64 38 January 10, 2020 07:28PM

Re: An error I didn't catch. Meant to type the 'b' and not the neighboring 'n'.

ToddB64 30 January 13, 2020 02:28AM

Re: Todd, an answer about 'Metal Detector Filters' regardless of operating frequency range.

ToddB64 39 January 10, 2020 02:35PM

Rob's write-up is interesting, and points out some of what I remind folks quite often.

Monte 39 January 11, 2020 09:22AM

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