I have read a number of sites that have said that 48v phantom power is too strong for these small lapel mics. I have to think that this is true if a company like Sony provides a barrel type battery power supply for its most expensive, professional lapel mics. These barrels terminate in an XLR connection, which would surely negate the need for a battery as they could run off of the board's phantom power, so why do they use a battery if that is the case? As I said at the start, I do not understand electronics, but these battery power packs seem to suggest that a lower voltage is preferable with a smaller lapel mic.
As far as the guitar goes, I have a piezo pickup already installed, but I want to try the internal mic (which is commonly used by many pros like Martin Carthy) too with a view to running a dual system (which are also commonly sold). I plan on making the mic removable, so that I can take it off when not playing live; it's also possible that it will not sound good enough, in which case I will remove it. The point is, is that I want to try it with a mic that I already have. As I said above, Martin Carthy has used this type of mic internally (a cheap Radio Shack model from what I have read) with really excellent, natural sounding results, so I am sure I will be able to get a decent result if I think it through and spend some time on it.
Thanks again,
Gary.