I started using metal detectors in March of '65. The 'standard' coils for most models ranged from 6" to 8", and from the latter '70s through most of the '80s the 'standard' size for most makes and models was from 7" to 8" Then in late '87 and early '88 we saw White's introduce the "Blue Max 950" and they said it was because consumers wanted more depth and a little better coverage. At the manufacturer's presentations at the Texas Council of Treasure Clubs that year, Alan Holcombe, their market guy who moved on up to CEO, told the audience he wanted to clear the air. He told everyone that he felt they had made a mistake and the former 'standard' 8" was better balanced and the better general-purpose performer. I and many others agreed and he and I discussed coils and models periodically for over twenty years on some of my visits to the White's factory.
Keep in mind that the bulk of the recreational use of metal detectors was started in and had a surge in the USA where hobbyists Coin & Jewelry Hunters searched parks, schools, yards, many, many other places and beaches. Since '68 I started using a 6" coil instead of an 8", and from about '71 to the present the majority of my detectors have been equipped with coils from 4½" to ± 7", and to this day I use smaller-size (under 7" diameter round) coils mostly, and in more open areas I opt for a mid-size coil. Those include the round 7" Concentric on my Impact, 5X8 DD on a Vanquish 540, and the 5X9½ DD's on a CoRe, Relic and ORX. I very seldom make use of coils larger than those because most places I hunt have too much trash, a lot of dense brush, weeds, rocks or building rubble.
But Minelab started using the 'over-size' 10" and 11" round DD coils a couple of decades ago, and other makers started using over-size coils as well. The 7+"11+ BiAxial for the Teknetics and Fisher models, 10 " and 11" round coils from White's, 9" and 11" coils from XP and the list goes on. Those bigger coils might be OK for working a wide-open beach or large grassy park or covering the plowed fields in the UK and elsewhere, but to me a lot of detectors come with over-size coils as standard and a lot of newcomers to the sport canty hunt well with them, they can't handle the trash, and many simply can't afford any smaller-size accessory coils. To me, a 'standard' coil on the affordably-priced Simples + should have been a 7" Concentric and not an 11" DD.
I love my Simplex + and I want to use it more often in more of the day-to-day hunt sites I visit ... but I need smaller coils. Plural. An 'OOR' shaped or round 5" DD is a 'must-have' for the very densely littered sites. A good 7" round Concentric coil would make an ideal 'general-purpose' coil, or if not it then a 5X½ DD open-frame coil would do, but a 7" Concentric would be preferred. I started using a DD coil back in '71/'72 and Concentric coils have been around nearly as long.
Matter-of-fact, the majority of the detector manufacturers in the '70s, '80s and '90s made Only Concentric coils or mostly Concentric coils, and even into the start of this century. I see no reason why a good 7" Concentric coil can't be made for the 12 kHz Simplex +. And if somebody tries to explain it off as the modern digitally designed circuitry works with a DD but not well with a Concentric, then maybe, just maybe we should have continued using good analog detectors? Maybe the modern digital designs are not all that good if they can't be made to function with a Concentric coil? And if the multi-option frequency and multi-featured Racer 2, Impact, Multi-Kruzer and Anfibio Multi can be designed to work with a 7" Concentric, there's no logical excise a 12 kHz Simplex + can't.
I don't want a 9" sized anything or a 15" coil, either. Just a 5", 7" and elliptical 5X9½ and the Simplex + will be well equipped.
Monte
