I'm working on a project for the elementary school that I work at. We have a class observation system where people take these very old speakers (built in-house) and plug them in to a 1/4 in jack outside the classroom. The mics inside the classrooms, as far as I can tell, are electret mics, but they draw power from the speaker when someone plugs one in. We're trying to update the system a little bit to use portable mp3 speakers rather than the old bulky ones we have now as those are pretty much useless, but everything we've tried doesn't seem to work. We've tried using 3.5mm-1/4 in TRS adapters (both stereo and mono) and neither worked. We also tried rewiring the connection using a 3-conductor stereo phone jack from radio shack (basically seeing if it would work if the connection was just 3.5 mm) but that didn't work either.
Can anybody offer any advice? We're trying to find a solution that doesn't break the bank and so far we can't seem to find anything that actually powers the mics and gets sound from them. Is the problem with the mp3 speakers or with the connection? or both?
Thanks in advance for all your help! I'm a bit of a novice when it comes to this so any help will be great, thanks!