Minelabs 800 Question About Sensitivity And Recovery Speed

[Gary985112]

Hi everyone,

I just had a question as it seems like the goal is to detect deeper targets, so it would seem that you would want to achieve as much depth as possible. 

When I lower my recovery speed from 6 to 5, I should be getting a little bit deeper measurably, Is that correct?

WWould increasing sensitivity get me more depth as well? I was just wondering their comparison between lowering recovery speed and depth, versus what role does sensitivity actually play?

Does sensitivity just help amplify targets and not really get you any deeper?

TThanks so much. 

 

 

[Knomad]

In most soil I think you will find that the sensitivity setting will affect your detection depth more than the recovery speed.

A slower recovery speed gives you and the detector more time to detect and hear the target, so has a little effect on the depth.  But a higher recovery speed is much better for separating close together targets, it can also help with detecting small targets in bad ground, this is why with the Nox 800 Gold Mode default recovery is pretty high at 6.

[midalake]

5 hours ago, Gary985112 said:

When I lower my recovery speed from 6 to 5, I should be getting a little bit deeper measurably, Is that correct?

Nope>>>>

[Valens Legacy]

Sensitivity is where you will get the depth on the 800, and with a larger coil it will go even deeper.

[Badger-NH]

Both Sensitivity and Recovery Speed affect depth.

Set the Sensitivity as high as the machine will allow and still remain stable, then set the Recovery Speed to the site conditions. In all metal, if you hear a lot of low tones with each swing of the coil, you might want a higher Recovery Speed for better separation of targets. If there are not a lot of low tones, you can lower the Recovery Speed for more depth. Low tones are caused by iron and/or mineralization.

In my test garden, lowering Recovery Speed increases depth until you get to 4. Below 4 does not have much if any affect on depth. In normal clean ground with few low tones, I usually set my Recovery at 4. 

At sites with a lot of low tones, higher Recovery Speeds will give you better target separation but a lower Recovery Speed can still pick up deeper targets in those same conditions. It pays to search iron infested and/or mineralized sites with both high and low Recovery Speeds.

 

[Northeast]

I am sure I remember Steve H writing on here somewhere that just because you can set your recovery speed fast, it doesn't mean you need to swing fast.  

Setting your recovery speed at 6 or 7 and then sweep with a mild swing speed might open up those squeakers that are hiding between the grunters  👍   (disclaimer: after 4 years with the Equinox I'm still a noob!). 

You've probably already read these but worth posting anyway.  

https://www.minelab.com/community/treasure-talk/recovery-speed-target-masking#:~:text=Recovery speed defines how quickly,coil at the same time.

 

 

 

 

[Jeff McClendon]

On 1/21/2023 at 5:20 PM, Gary985112 said:

Hi everyone,

I just had a question as it seems like the goal is to detect deeper targets, so it would seem that you would want to achieve as much depth as possible. 

When I lower my recovery speed from 6 to 5, I should be getting a little bit deeper measurably, Is that correct?

YES.

From the air and in the ground testing I have done with both the 800 and 900, there is a 3/8" to 1/2" difference between recovery speed setting 4, 5 and 6 which are the settings I normally use for everyday hunting in moderate mineralization on USA coin sized targets even using default 20 sensitivity. This testing includes Beach 1 and Beach 2. Some have said here that there is no difference. Others have said that settings 1, 2, and 3 don't offer much difference. I haven't used or tested those lower settings so I can't comment.

Lowering recovery speed lets the detector spend a fraction more time on a target and will elongate the audio responses just like raising the recovery speed will abbreviate the audio responses and shorten the time the target is checked.

If you have two targets with similar size but different conductivity that are not at the same vertical depth but are overlapping, the one that is closer to the coil may have an audio response that overpowers the target that is deeper if the recovery speed is set lower for example. If the recovery speed is raised, both targets might be able to give enough of an audible response to know there are two possible targets.

Sensitivity may help to amplify the signal response of deeper targets and to create more accurate target IDs and audio responses. Raising sensitivity will also amplify other signal responses from tiny bits of trash and amplify responses that are not recoverable targets like ground interference and electro-magnetic interference.

 

 

 

[Chase Goldman]

17 minutes ago, Jeff McClendon said:

YES.

From the air and in the ground testing I have done with both the 800 and 900, there is a 3/8" to 1/2" difference between recovery speed setting 4, 5 and 6 which are the settings I normally use for everyday hunting in moderate mineralization on USA coin sized targets even using default 20 sensitivity. This testing includes Beach 1 and Beach 2. Some have said here that there is no difference. Others have said that settings 1, 2, and 3 don't offer much difference. I haven't used or tested those lower settings so I can't comment.

Lowering recovery speed lets the detector spend a fraction more time on a target and will elongate the audio responses just like raising the recovery speed will abbreviate the audio responses and shorten the time the target is checked.

If you have two targets with similar size but different conductivity that are not at the same vertical depth but are overlapping, the one that is closer to the coil may have an audio response that overpowers the target that is deeper if the recovery speed is set lower for example. If the recovery speed is raised, both targets might be able to give enough of an audible response to know there are two possible targets.

Sensitivity may help to amplify the signal response of deeper targets and to create more accurate target IDs and audio responses. Raising sensitivity will also amplify any other signal responses that are not recoverable targets like ground interference and electro-magnetic interference.

 

 

 

One additional thought on this excellent post by Jeff - just as there is a point of diminishing returns (i.e., additional noise and lower stability (that manifests as chatter)) when increasing sensitivity, there is also a point of diminishing returns when lowering recovery speed.  Besides the fact that users have reported little difference in their ability to hear fringe targets at the lowest recovery speeds vs. the typical defaults (4, 5, and 6), lowering recovery speed beyond what is necessary will also cause you to hear more ground noise which will be picked up as chatter in hot dirt as well as wet salt sand.  So really, the name of the game is optimizing the settings to give you the desired separation and depth capability as well as minimizing chatter and ground noise (maximizing signal to noise ratio).  Many people have noted that ML has done a pretty good job at setting the defaults for the user adjustable parameters such as sensitivity, recovery speed, and iron bias at pretty good starting points and only slight adjustments for site conditions usually all that is needed to make them optimal if they aren't already there.

[JohnnyRox]