View Full Version : frequencies

03-26-2015, 12:44 PM
Which is better a lower frequency machine or a higher one? I notice that Garrett Ace 350 has a frequency of 7.5 and the Garrett pro has a frequency of 14.5 and then other machines in the same price range like minelab has a higher frequency.Does it matter? Anybody have an answer for me thank you.

03-26-2015, 01:39 PM
The frequency affects what you are looking for. I was told by a dealer that anything below 20 kHz is good for coins/relics; It doesn't really matter. However, I take that with a grain of salt. Theres no way to refute the laws of physics, or electromagnetism. Generally the higher frequencies are more for prospecting because the higher frequencies pick up the gold flakes better. Lower frequency machines have lower attenuation on the return signal so they can hit those coins well. To compensate, the higher frequency machines need higher gain receivers. Mine is a 6.9kHz and I don't miss too much. A few on here have the ATP which is the 15 kHz +-97Hz and they been getting some good finds with them. Theres always a trade off and there are things at each end of the spectrum will miss. I personally would prefer to have it under 8kHz if it's single frequency. If you intend to hit saltwater beaches, you might want to look into dual/multiple frequency machines. Single frequency should be fine at freshwater beaches. Look also at the other features of the machine. I'd want a depth indicator, VDI, and target category. Many tones are good so u don't always have to look at the screen.

Lodge Scent
03-26-2015, 03:00 PM
Like Mango says, the optimum frequency depends on what you are looking for and what your site conditions are like. Any machine at any frequency can find the easy targets. When you factor in target depth, soil conditions, target composition, target size, EMF, etc., using the right frequency for the conditions at hand can make all the difference. I've often had marginal signals on nice targets basically go away when I changed frequencies. The opposite is also true of course. If I only had one choice, for the majority of hunting I do, an 8kHz would be a general frequency that I could live with. I wouldn't be happy with it all the time though. It is nice to have multiple frequency options !

03-26-2015, 07:12 PM
Thank you veery much for your answer.I guess it makes a lot of sence.Trying to figure out which machine to purchase next as Im told to go with a minlab but don't see any difference between the minelab and the Ace 350 or the Garrett Ultra GTA1000,but Im told the minelab will put the Garrett to shame as far as depth and performance.

03-27-2015, 06:49 AM
Nay. I was told too that only the CTX 3030 can see thru the mineralization. The minelab in the price range you are referring to are prob the xterra series. Although you can change the frequency of those machines, it's achieved by changing out the search coil. It works, but to me I would rather have the touch of a button versus having to lug an extra coil around. Sometimes the odd finds can be enough to carry around on their own. There's a bit of hiking sometimes so it's not like you can check the machine at the car and expect the soil to be the same a mile or two away. I think the GTA1000 is an obsolete model. Just be aware, too, that some of those YouTube videos are embellished a little.

10-29-2015, 09:50 PM
I don't claim to be an expert by any stretch of the imagination... but I have one of those Minelab Xterras... a 705 as a matter of fact, and on more than a few occasions I've compared the 18.75 khz frequency coil (for low conductors i.e. gold and aluminum) to the 3 khz coil (for high conductors i.e. silver). I have not yet found a situation here in S E Michigan where the 3 khz coil out performed the 18.75 khz for finding coins or jewelry. I recently bought the NEL Hunter 3 frequencies (3, 7.5 and 18.75 khz) in one (at a time) coils for my Xterra 705. I hunted in a straight line with the Detector in 18.75 khz mode (my favorite) down the sideline of an entire Soccer Field with approximate 3 foot overlapping swings digging any medium to high pitch tones and dug several modern clad coins and pennies and scrap aluminum. I then switched over to 3 khz and re-did the same area and dug just two more Nickels... only at the end of the search field, that I just suspect, that I missed. This wasn't the first time I had done this experiment and experienced the same results. I prefer the 18.75 khz frequency because of the sharpness of the tones I get compared to the less sharp tones in the 3 khz hunting mode no matter what the target is comprised of. I'm hunting in low to mid mineralized soil.

10-30-2015, 12:18 AM
I have a bit of experience with the X-Terra running all 3 frequencies and I have notice a significant difference using them. The high frequency (18.75KHz)attunes to lower conductivity metals such as gold much better than the low frequency(3KHz) and is a killer at finding nickles. Also because of the shorter bandwidth the high frequency is great at finding very small or even tiny targets. I have hit on partial staples and flakes of lead in the past that the other frequencies won't touch. The drawback with high frequency is I have noticed a big loss in depth-I only get about half of what the 3KHz can do. That's where the low frequency really shines-if you are looking for the deepest coin size targets, low frequency is the way to go. On high conductive targets such as silver it can't be outdone on a single frequency machine. With my NEL coil I have gotten silver at 14 plus inches, and have seen ground coin tests reaching about 2 feet. (Likely ideal conditions and clean soil-not likely in the field, but shows the potential)

As a side note, if you do decide on an X-Terra 705 and decide you want a NEL 3 frequency coil I "may" be talked into parting with one of mine. Very low use as I just got them maybe 2 weeks before I got a great deal on a CTX.

10-30-2015, 04:12 AM
2 foot deep coin finds? That's gotta be a record!!! Was that in sand or soil? You don't fish too, do ya? LOL. I understand the difference in wavelengths and the premise that lower frequencies travel deeper in the ground. It's analogous to high frequency coils being a fine threaded bolt and low frequency being a coarse threaded bolt... It's a lot quicker to screw-in the coarse threaded bolt compared to the fine threaded one. I'm basing my statement about my preference of 18.75 kHz over the 3 kHz based on my own experience in direct head to head (preliminary) experiences... We'll see if those results change as time goes on.

10-30-2015, 06:14 PM
2 foot deep coin finds? That's gotta be a record!!!

Well, I was a bit amazed too-admittedly it was 30 sensitivity in ideal conditions, large coin using the NEL 15" coil at 3KHz. The other frequencies were significantly less.