Getting the best from the SDC2300

REVISED – June 2020

A few notes on the new version!
SDC2300 is now shipping as a new version. The main detector unit is still the same, but Minelab have added some cool new additions to the pack, to make this detector even better straight out of the box. A neoprene armrest cover is now supplied. The Koss UR-30 headphones are gone, and a new Minelab branded headphone is included. They have a nice solid feel, but are very comfortable. The headphone cable can be removed, and uses a twist lock mechanism to attach, so spares can be purchased and kept handy in case of any breakage in the field.
There is also a perfectly fitting knuckle protector that has been a standard inclusion for a little while now. The biggest improvement is a sealed drop in Lithium Ion pack, which replaces the 4 x C Cells, but C Cells can still be used if one wishes.

It’s no secret that I’m a big fan of Minelab’s SDC2300 gold detector. Its effectiveness and simplicity is simply unmatched. Here’s how easy it can be:

Quick Set-Up

Simply turn it on, set the threshold to the 4th led, set the Sensitivity to 2/Green, and with the coil up off the ground press the Noise Cancel button. Now press and hold the green ground balance button, pump the coil a few times between 10cm and the ground surface, let go of the button and you’re ready to hunt.

While the SDC2300 is pretty light on in setting options, to many users this is part of the appeal, but there are a few tricks to getting the best performance and results out of the SDC2300. Here are a few things I’ve learnt with the unit, and what works best for me.

1. Noise Cancelling

Through improvements in the general circuitry, the SDC 2300 isn’t as effected by sources of Electromagnetic Interference (EMI) as much as say a GPX series machine is, but due to the high sensitivity of the unit and general sharpness of the audio signals, even picking up slight amounts of EMI will result in a chattery threshold that can mask a genuine target response. In my experience with the unit in the Adelaide hills and parts of the Victorian goldfields, I have found it very critical to perform a Noise Cancel to allow the unit to select the quietest operating channel for the area you are detecting in. You should always do a Noise Cancel at the start of a session, and repeat when necessary.

Before pressing the Noise Cancel button, I find that for best results you should have the coil in the orientation that you will be swinging it. I.e. if you are detecting on flat terrain, then your coil should be kept parallel to the ground. Or, if you are about to detect a slope then keep your coil at the angle of the slope. Now, regardless of the coil angle, it is important you raise the coil up off the ground, to expose the coil to environmental noise.

TIP: If your threshold is quite stable when you raise the coil off the ground, increase the Sensitivity to 5 before pressing the Auto Tune button. Or just do this regardless.

Hold the coil steady up off the ground, at the angle you will be sweeping it, and then press the Noise Cancel button. During the tuning process, keep the coil very still. When the Noise Cancel procedure finishes, drop the coil to the ground, set Sensitivity back to 3 and listen to the threshold to see if there’s any improvement in stability. If you feel that the threshold stability hasn’t improved, then repeat the procedure. While it may sound like a chore, trust me, when you get the unit humming it will repay you in finds, as target signals stand out much better, and you may even be able to increase the Sensitivity.

2. Sensitivity

The Sensitivity of the SDC2300 is critical to getting the best performance of the unit under different conditions. Traditionally the Sensitivity or Gain setting on a gold detector needed to be set to suit the ground conditions, but on the SDC the Sensitivity level is dictated more so by the level of EMI (Electromagnetic Interference) in a location rather than the ground conditions. The SDC2300 handles ground so well, that in most areas you can have the Sensitivity on the maximum setting of 5! In simple terms, set it as high as you can before the detector becomes too erratic. Higher Sensitivity settings seem to also have a bit more volume, so this will help in hearing those faint threshold variations, so the higher the better, but don’t go too far if conditions don’t allow it. Some of my deepest digs have been with the Sensitivity on 1, but the signals were a faint variation in threshold tone that could only be heard through good headphones.

Some SDC operators run the Sensitivity “flat out all the time”, i.e. never take it off Sens 5, and while this can be quite productive under certain conditions, I find it can be a handful and more of a distraction due to the instability of the threshold. I have found that if using headphones, I prefer a smoother threshold as the sound is right on my ears so I won’t have any trouble hearing a faint signal. But if using an external speaker, you need all the help you can get in the volume department, so having the Sensitivity on 4 or 5 works well – the slightly erratic threshold is less of a problem when the sound isn’t directly on your ears. So my general rule of thumb is:

When using headphones: Sensitivity 1-3

When using booster/speaker: Sensitivity 3-5

3. Coil Sweep Technique

To maximise the effectiveness of the SDC, it is important that you sweep very slowly, and keep your coil low to the ground – lightly skim the ground where possible. Getting the coil even 5mm closer to the ground can be the difference between hearing a target or walking over it. Just as important is to make sure you overlap your sweeps – this is very critical to achieve maximum depth on the smallest targets. Just think of how small some of the targets you are looking for are, and at maximum depth you may only be covering a very small area.

TIP: If attacking a large set of old diggings, do small sections carefully rather than trying to cover too much ground and you will find gold.

4. Phase Technical Adaptor Lead

Out of the box, you can use the in-built speaker on the right hand side of the SDC (quite good for left handers), or the supplied headphones. Due to the special style headphone connector on the control box, it isn’t possible to connect other headphones, or external booster/speaker combos. This is where the Phase Technical SDC2300 Adaptor Lead comes in. It features the same quality headphone connector on one end, then a short heavy duty fly lead with a 1/4″ (6.35mm) female socket on the other end. This allows you to connect your favourite pair of headphones, or booster/speaker combos for extra performance. The adaptor lead isn’t designed to be an extension cable, so must be fixed in place either under your arm rest, or secured onto your control box cover using zip ties – see the image. If the wire doesn’t move, it can’t break.

5. Quality Headphones

I’ve said it hundreds of times over the years, and I’ll say it again “If you don’t hear the target signal, you won’t be digging up that nugget!” With any gold detector, audio is the most important thing, so why skimp on headphones that are not built for the task? There are literally thousands of headphones on the market these days, but one thing most of them lack is durability. Of the handful of headphones available that are quite durable and can withstand a bit of punishment (generally dj style headphones), most are built for music playback, so to make them sound “good” the low end and top end audio frequencies are often enhanced. Some headphones are so bass heavy that the overall clarity of the audio just isn’t there. Nearly all gold detectors provide signal responses in the mid-range audio frequencies, so bass and very high end frequencies are less critical, so when it comes to headphone performance what you need is a flat frequency response, and ideally an enhanced mid-range. “Monitor” style headphones have a more natural or flat frequency response, so while they appear quieter when you put them on, faint nugget signals are heard quite easily – as long as it isn’t a windy day! The other problem with Monitor headphones is that they are designed to be used in studios, so are generally not robust enough for use while metal detecting.

This is where the choice of suitable headphones gets extremely limited, and not being able to find the perfect pair, I have worked with several custom headphone makers to produce the ideal set. The latest Recon-ST headphones that are custom built for Phase Technical, really tick all the right boxes. They feature specially selected 150 Ohm drivers, with the sound itself being very geared towards mid-range frequencies – both features enhance your ability to hear the often faint signals produced by the SDC (and other gold detectors such as the Minelab GPX series, GPZ 7000, Makro Gold Racer etc). The build of the headphones is very robust, yet they are very comfortable with thick padded ear pads so can be used for long periods of time. As an added bonus, they will block out a lot of ambient noise, so external distractions are minimized. The curly cable is just the right length and has good flex, and features a quality Amphenol right angled plug to reduce strain on the termination point. I guess when something is built for the gold prospector, you can expect it to tick all the right boxes and the Recon-STs deliver.
NOTE: New version Recon headphones currently in development.

6.External Booster / Speaker combo

As much as I love using quality headphones, some users hate them for different reasons, but the most complaints come from operators who detect in hot or humid climates. I agree, and on those hot days, particularly when there isn’t much wind about, the headphones stay in the gear bag. The SDC2300 lacks an adjustable volume control, and while the internal speaker is quite loud, for a right handed operator the sound is pointing in the wrong direction. The Phase Technical adaptor lead also gives you the option of connecting an external audio amplifier/booster, giving you a volume control and enough power to drive an external speaker. You can then mount the speaker in a location where you’ll stand a much better chance of hearing those faint signals. For external speaker use, I use and recommend the SteelPhase sP01 Enhancer, which I mount on my Pro-Swing harness where the GME speaker is permanently clipped onto my left shoulder strap. This puts the sounds directly towards your ear, so you don’t need to crank the volume too high.

7. Ground Balancing??

There is a question mark after ground balancing for good reason – most users are a bit baffled with the ground balance on the SDC as the unit nearly always appears to be balanced. I think the 2300 is equipped with one of the best Auto Tracking circuits ever made – it just works and works very well. One tip I will give in relation to ground balancing is to regularly stop sweeping your coil and just give the coil a couple of pumps. This isn’t always necessary, but I like doing it just to be sure that the ground balance in perfectly maintained in the event that it may be slightly out, after detecting through a big change in ground mineralisation.

8. Location, location, location

These days to be a successful prospector, you are not only required to have good technique, good gear, and good spots, you need to use your particular detector to its strengths – e.g. work out what are the key benefits over your detector compared to previous/other detectors, and then use that in the right area. For the SDC2300, its key benefits are how quiet it operates in mineralised soils, particularly its ability to ignore charcoal, and also its high sensitivity to low conductive targets – its reputation for finding specimen gold (in quartz, ironstone and others) as well as porous/prickly gold is now well established.

So, to get the best results from the SDC, you should use it in mineralised and shallow ground, and especially where gold is known to be close to the source. Picture a very long set of diggings where the head of the diggings are quite shallow and start at the base of a large hill, and then meander down the gully into deeper ground. Generally speaking, the head of the gully will have rougher textured gold, and more mineralised shallow soil, while further down the gully will be deeper ground, less mineralised due to a greater amount of topsoil, and the gold will be more weathered, giving it a rounded lumpy appearance. Due to this, metal detectors in years gone by that may have struggled in mineralised soil and didn’t have very good sensitivity on the rougher “un-weathered” nuggets, would have been far more effective on the lower section of diggings. So it should be the case, that you would have more success around the head of the diggings using your SDC2300. This is just a generalization of one possible scenario, but it’s a tip that has produced for me in a number of different locations.

Well I hope this blog has given you a tip or two to help you in the hunt for those elusive yellow rocks!