Hello hello folks,
I did use Emotiv for a while (with the EEG SDK) and switch to openBCI, been using both for brainwave detection for couple of years. Recently I receive my Gaglion boards too.
First , UltraCortex and the chin strap is not compulsory in my experience. The gal is keeping the sensors and I had good signal with gal only (not a lot of mobility thou), in my early prototypes I actually used just a winter hat to keep the sensors fixed. Later I made my own velcro headband, but I’ve also seen similar for $20 or so on the web. UltraCortex, I think, is giving you the advantages of using moisture instead of gal as well as the easier sensors placements, but it was too expensive for my case.
Most of the functionality from openBCI GUI for the Cyton board is not yet ported to Ganglion, but it looks promising. You would need to steam the channels input and do the filtering yourself, not long and trivial processes but ganglion just shipped and there is not much out, yet. NeuromoreStudio is great solution in general and offers a graph interface with bunch of examples and OSC, but no support for Ganglion yet and some strange pricing options, which I haven’t really know about since I used previous open betas. openBCI is providing great documentation and software libraries, like NodeJS and Processing, which is just lovely, but the Ganglion GUI is …in the process… Dunno when the full functionality is coming, but as the name of the product suggest, ‘open’ means you can easily do stuff if you want.
Brainwaves detection with fewer channels is indeed somewhat possible, but I don't believe it will be good representation of brainwaves with only one channel. After all, one sensor means only one part of the brain so you cannot really make an objective picture. I did have the daisy module for a while, so I made tests with both 8 and 16 channels and was even happy with as low as 6 channels for my project. To be honest you can go with 2 sensors if you focus on frontal cortex for example and Alpha-Beta waves, but I'm not sure how far research is with association of brainwaves and parts of the brain when it comes to meditation. The 4 sensors however go nicely in front and the back, which is somewhat complete chain. Here it comes the tricky part in my perception, by having 4 sensors you can monitor signals on top or the edges of the head and some people do have different personality related to which parts of the brain are used. So maybe we need to place sensor slightly different locations depending on the person and such adjustment would be possible, but less needed with more sensors. The 16 sensors setup allow us more information from more regions of the brain, hence higher resolution brainwave readings and the possibility to discard channels without effecting much. This week I was playing around with 3 sensors on Ganglion because one was not active and I didn't fix it for the sake of experimentation and while it was acceptable case it was very frustrating to have some part of the brain data completely in the dark... so yeah, any number of channels would allow you to define present brainwave, but the more sensors in your chain you have, the better you would be able to define the dominant brainwave and the given brain state. Probably 4 and 8 are the commercial minimum because it does represent somewhat complete net on the head.
The classification of the meditation in Emotiv (which is different suit than the raw EEG/brainwaves approach) is done by sampling many buddhist monks. I did not manage to record high meditation activities in my previous tests, but in theory you can teach your own system to classy mediation, probably just as good with openBCI and large enough valid meditation sample. Emotiv does have (sort of) learning abilities, as the device gets more accuracy over time for a given person (profiling), which is sort of cool. With openBCI the provided raw EEG signal, needs to filter and to classify meditation.
To make the long story short, openBCI does offer sort of barebones products with better quality of signal, documentation of the software, access to your EEG data and (most importantly) updates. Emotiv and Muse (probably others too), however does offer more 'commercial' ready product, where you can get classified data to dashboard and recording it, but somewhat limited access to the raw EEG data. I would choose openBCI any day, but you cannot easily ignore the experience completeness of emotiv and other commercial package. I’m not sure how non-developers make the choice, as it's not easy.