Afternoon, all...
A bit of rummaging with microphones on Balloon2.05 this morning 
- there 2 issues, if anyone wants to just hang a PC microphone 
straight off a Balloon (which,to be honest, is only really expecting 
line input, the microphone feature was just an (optimistic) last-
minute thing.)
First - microphone levels are rather low. Slapping in a x100 gain 
block (Maplin N69AW worked very well for £6, if needed for 
prototyping)
Second - the phantom power to the microphone isn't clean 
enough, and you get a 'pock' noise every time the 3V rail drops a 
bit (when the CPU comes out of idle). If you remove the phantom 
power resistors (R17, R18) and the pulldowns (R19, R20), and 
use a battery-powered mic, the quality's pretty darn good, 
though. 

Since the gain block stops the phantom power from getting to the 
mic anyway, this pair of mods go pretty well together. 
Balloon3 will have better power isolation to drive the mic, 
assuming I can find the space. 

Steve