Recovery Speed & The Conveyor Belt

[Steve Herschbach]

I love analogies. Maybe this one will help some people.

Low recovery speeds magnify signals and fast recovery speeds truncate signals. Digital machines usually chop signals into discrete portions. A target is “grabbed” and then it is “released”. A new target cannot be “grabbed” until the last one is “released”.

Imagine a conveyor belt going by with a line of wooden blocks. The blocks have anywhere from 9 to 16 sides. You are standing there blindfolded as the blocks go by. You can pick up a block and feel it for as long as you want to try and decide how many sides it has. The longer you roll it around in your hands, the better. Your chance of deciding if it is a thirteen sided block or a fourteen sided block is better if you have more time. However, you are being graded by how many blocks you identify correctly, and if you hold one too long some pass by before you can pick them up.

The conveyor is passing 8 blocks per minute past you. If you have a recovery speed of 1 you hold each block one minute and you get a great “signal” on that block. But seven other blocks go by as you are taking your time identifying the one block. You increase your recovery time to three and now get 3 out of 8 blocks but have less time to hold each block. Less signal information. Still, you get them all right. Now you increase recovery time to 5 and are only missing three blocks. Your slower buddies are having a hard time keeping up now and making mistakes, misidentifying blocks, but you are doing great.

You notice that people standing back are having to reach farther to grab a block and put it back. They are “going deeper” but it is costing them time. You step closer to the conveyor belt so you don’t have to reach as far, and are now a little faster by not reaching as far. You lose a little “depth” but gain some speed.

You go to recovery speed seven and your arms are a blur. Your buddies all give up and stand back in awe as you pick up and put down blocks at lightning speed, and are still calling them right but you can tell you are at your limit. You finally go to 8 and still get almost all right it every now and then you have to put a block back down before you can tell what it was. You don’t have enough time, enough signal to work with.

You also get to change the conveyor speed. You can swing your coil slower, and now you have more time to look at each target. That means you can lower the recovery speed and still keep up with the targets. Great for the slower workers (detectors) who have a hard time keeping up.

That is a decent analogy for recovery speed and what it does for the ability of a detector to clearly examine a target versus how many targets it can process and how far it can reach. Slow detectors, slow conveyor workers, don’t have a chance. Only the fastest workers, the fastest machines, can pick up and process all the targets correctly in a short period of time. They are a rare breed.

One of the biggest advantages you possess in Equinox is the lightning fast recovery speed. I see far too many people throwing that advantage away thinking a lower recovery speed gets “more depth”. No point in getting an Equinox then, just stick with the slower machine you already have. Give Equinox a real good go at the default higher recovery speeds before deciding to toss away what is perhaps the most important advantage the machine has - lightning fast recovery time coupled with accurate target id and minimal depth loss at those high speeds. That is the Equinox difference. Don’t waste it.

Recovery Speed, Recovery Delay, And Reactivity

[Dubious]

A very good analogy and explanation.  Makes me wonder if I should trade my Equinox 600 in on the 800 at some point. The 600's speed scale is 1-3, and I believe 3 corresponds to 6 on the 800's 1-8 scale, so I'm missing the highest speed settings.  That said, I haven't noticed that I'm missing anything.  One of the things that immediately struck me about the Equinox is that, when I used it on a very trashy spot I've gone over multiple times with the Etrac, it was seeing a lot more stuff down there that the Etrac had been unable to separate.

[Steve Herschbach]

My Recovery Speed (Detect Speed) setting is at 6 nearly all the time. I might go to 7 in really dense trash. I see no real need for 8 - it's just there as an extreme "just in case" for some rare use. I sometimes drop to 5 and maybe 4 if I ever see low mineral ground with sparse targets. I don't see much added benefit to extra low speeds below 4 (2) and in fact I think they negate the whole reason why I have an Equinox. In high mineral ground lower recovery speeds may cause you to lose depth, not gain it.

For the 600 I would stay at 3 and only ever drop to 2 for the rarest of occasions. 6 (3) is where I would glue the control if I had to pick one setting.

[Rick K - First Member]

It’s easier to understand with a video.....

 

[Jackpine]

LMAO

Rick

I'm glad I scrolled down as I was about to post the same Lucy video. Had the link copied

[Chase Goldman]

Good question Dubious.  I think Steve covered it above, but regarding the differences between the 600 and 800 a lot of folks latch on to the obvious missing Gold mode and dismiss that mode as a prospecting mode that is not something they need or want (I personally disagree with this logic because I think Gold Mode can be used in relic hunting due to its ability to perform in highly mineralized soil conditions, but that is not the point of this thread) and completely overlook what I think are two key features one is performance based and the other is user interface based that are different between the 600 and 800.  The key performance-based feature is the recovery speed adjustment and the lack of the two high-end recovery speed settings on the 600.  (The user interface feature I think is the second most important "missing" feature from the 600 is the ability to adjust non-ferrous tone breaks, volumes, and pitch).  Are you missing much without those two highest setting?  Perhaps only in highly trash laden or iron infested sites so depending on how frequently you encounter those sites, you may want to consider the 800.  Also, if you can possibly afford it, I would recommend hanging on to the 600 as a capable backup if you indeed decide to ultimately purchase the 800.  I also want to re-emphasize that although I talk in terms of features "missing" from the 600, this does not mean that the 600 is not a good detector.  What it means is that while the 600 lacks some features compared to the 800, that is the wrong comparison.  The 600 represents a great value when its performance is compared to other detectors in its price range.  Pretty much unbeatable.  ML has given detectorists a value-based choice or a performance-based choice.  Steve covered this in detail in his 600 vs. 800 blog post.

 

55 minutes ago, Steve Herschbach said:

My Recovery Speed (Detect Speed) setting is at 6 nearly all the time. I might go to 7 in really desne trash. I see no real need for 8 - it's just there as an extreme "just in case" for some rare use. I sometimes drop to 5 and maybe 4 if I ever see low mineral ground with sparse targets. I don't see much added benefit to extra low speeds below 4 (2) and in fact I think they negate the whole reason why I have an Equinox. In high mineral ground lower recovery speeds will cause you to lose depth, not gain it.

I liked and agreed with your conveyor belt analogy especially with regards to "depth" (more on that below).  But I am really glad you wrote the above  because I have been struggling with determining when I would ever invoke the lowest recovery speeds.  In fact, I was a little confused by the following statement in the manual (p. 26) regarding the default recovery speed setting for Gold 2 which is supposed to be geared towards maximizing performance under highly mineralized soil conditions but also happens to have the lowest default recovery speed that ML attempted to explain below (bold text added by me):

"Gold 2: Difficult Ground
Gold 2 is best for searching for deeper gold nuggets
in ‘difficult’ ground conditions. Gold 2 has a lower
Recovery Speed, which will increase detection depth. However,
more ground noise in more heavily mineralised grounds may
result. Tracking Ground Balance is the default setting. Target Tone is
set to 1 and the audio is optimised for hunting for gold nuggets.
Gold 2 Multi-IQ processes a high frequency weighted multifrequency
signal, while ground balancing for mineralised soil."

I guess ML hedges their bets by saying that there is essentially no free lunch because although the lower recovery speed setting will "increase detection depth"  more ground noise may be present in more heavily mineralized grounds obviating the advantage which is somewhat consistent with what you were saying above about "losing" depth.

On a separate note, for the Equinox, I think of recovery speed less in the context of trading "target depth" for "target separation" but instead, trading "the most accurate target ID at depth" for "target separation".  In other words just knowing a non-ferrous target is there amongst the iron (even if you don't have a stable ID) is often an advantage vs. slower machines that will not register an ID at all.

So I guess I don't really have a question other than wondering whether ML hit the mark with their Gold 2 explanation on recovery speed.

Thanks.

[Steve Herschbach]

The statements in the manual are nothing more than generalities and how well they match with reality just depends on ground conditions and target mix. Even my own statements are generalizations only and have to be taken with a grain or even a lump of salt.

[Norm S]

I actually remember that Lucy show when it aired. I hated that show but we watched what mom & dad wanted to watch

[Guest calabash digger]

Thanks for posting that I wondered what your lowest speed was. I ran it in 5 in clean ground the other day and 6 and 7 in the iron the other day. I saw some dropping it to 1 or 2 on the other forum. 6 is probably gonna be my sweet spot for general relic hunting... hmmm think that's the default in park 2.

[Steve Herschbach]

You have probably already seen it Scott. Find a deep target and test, and increasing recovery speed causes almost no discernible loss of depth. The target sound gets shorter, but that is about it until you get to 8, where it can shorten out of existence. In my ground anyway lowering recovery speed adds no depth worth noting but significantly increases the risk of masking. In my opinion any extra targets gained by any minimal depth increase at lower recovery speeds is vastly outweighed by the risk of targets lost due to masking. In bad ground a lower recovery speed increases ground noise, again making any real useable depth gain debatable. In my worst ground (and it’s Really bad) I am just not seeing it.

More to the point, aren’t people trying to pull targets out of ground already pounded with BBS/FBS detectors? If so, then where is the reason in trying to turn Equinox into BBS/FBS if those machines have already been used and can find no more? Remaining targets, if any exist, will be there due to masking. Even ground with low trash still has trash and that trash can mask stuff. And there really is more to Multi-IQ than just speed and masking. I can’t put my finger on it but I know it’s there. It sees stuff other machines don’t see, plain and simple as that.

People really need to let Equinox be Equinox. Trust that the defaults are close to what you really want, no matter what, for at least the first week or two. Immediately dropping to recovery speed 1 or 2 when the default is 6 and the user has no prior experience with the machine is really just kind of nuts. I think most poor results people are having is trying to outthink the engineers. Trust me, they are way, way smarter than any of us when it comes to what makes Multi-IQ tick and what settings are best.