Sorry if this point has been covered before but I can't find any previous posts specifically related to this point.
I've also posted this on melodeon.net. Hope that's not bad form.
We've just purchased the M310 melodeon system and 2 M400s for use with a concertina. We used them for the first time, in a gig, last night and are very pleased with the performance. None of the feedback or noise issues that are regularly reported and a decent enough reproduction of the sound plus the freedom to wander round rather than stand in one spot pointing at a mike which, in itself, was worth the cost.
The only negative we've found is that the velcro is terrible! Both the large melodeon bar thingy and the two concertina ones spent the evening hanging by two or three little hooks, in spite of some rather assertive pushing together of the two velcro strips. Admittedly, they didn't actually fall off but it was rather disconcerting and, as a novice melodeon player, any distraction is most unwelcome.
So, to the point. I'm considering getting some magnetic strip and replacing the velcro with a magnet/magnet or magnet/steel arrangement. The specific question is (please forgive my ignorance if this is obvious) is the magnetic field likely to interfere with the functioning of the electret microphones? Also, more generally ... has anyone tried this and did it work?