I agree with the points expressed in this thread, and I would like to add a few thoughts and observations.
As an engineer, I definitely designed the ICES-PEMF system to have a simple and practical way to orient the magnetic field lines certain specific ways. This was based on the published tissue responses to applied electrical fields, and my original design intent was to design ICES-PEMF to use electro-magnetic induction to induce equivalent fields in the deep tissues to have similar effects to electric fields.
I think I generally succeeded in this, and to that extent there are “correct” ways to stack coils to achieve these magnetic flux line directions, and thus the resulting electrical fields. So far as all that goes, I think the system works pretty well.
But then quite a few people started telling me that they were getting good effects when they stacked or oriented the coils in ways that I would have calculated were “incorrect”, because they would tend to cancel the magnetic fields. But people just kept doing things I advised against, and quite a few people claimed very significant benefits from using the coils stacked the wrong way. Some of these were people who I know to be reliable observers. For example, they would insist that the “wrongly” stacked coils worked well for them. But later, they stopped working so well and then they noticed that one of the coil wires had broken. When replaced with working coils, they once again had good biological benefits from these “incorrectly” stacked coils.
So, I started thinking about this, because it shouldn’t have worked at all; the fields should have cancelled.
But when you look at it more deeply, it starts to make some sense (maybe)
This is because magnetism does not work like light. One example: if you have two beams of light in a dark room, the beams can move around separately, or they can cross, but the light from one beam does not interact with the light from the other beam. (physics nerds: assume non-coherent light, which is a safe assumption for typical beams such as flashlights)
Magnetism is completely different. Any two magnetic fields in the same space will always interact. Consider the example of two separate powerful magnets. When you try to push them together but with like poles facing each other (South-to-South, or North-to-North), the magnets will repel. The closer they get, the stronger the repelling force. Here is the interesting point: the magnetic fields do not cancel when you do this, they just deform eachother. Directly between the magnets you will measure zero magnetic field, but not because the fields cancel, rather it is because the fields are disported away from eachother.
And it is clear that the fields to not cancel out, because they continue to generate a large repulsive force between the magnets.
So, by analogy to powerful fixed magnets, you end up with a lot of magnetic field distortion, but not necessarily cancellation, when you stack the coils incorrectly. And it is currently my opinion that in some cases, these distorted magnetic field vectors still have significant biological effects.
I did not believe this was possible at the beginning, years ago. But the number of positive observations of this effect has convinced me that a simple understanding of bio-magnetic effects is just not nuanced enough to capture the full range of effects and responses that people have to PEMF.
And the reason you do not see this using the hexagonal coil tester is that the coil tester was designed to test coils individually or when stacked “correctly” with simple, predictable magnetic flux vectors. But with the distorted fields from “incorrectly” stacked coils, you will not detect the distorted fields properly with the coil tester, because it us simply not designed to detect the distorted fields.