Regarding building a tube mic pre, I would probably have tried:
http://www.tangible-technology.com/tubes/altec.html
FREE SCHEMATICS can also be found here:
http://nanaimo.ark.com/~pat/
1. THE FABULOUS... TUBE HI FI PRE-AMP!!!! - a line level amp.
2. MAKE YOUR OWN....BALANCED MIC PREAMP!
3. MAKE...