ouuuch! 'let's build a flame war'
back on the subject! here's the main parts of a mic preamp:
input/unbalancing section can be transformer (easiest but costly) or solid state (be careful of CMRR)
gain stage opamp(DMIC, other mid-grade pres), instrumentation amp (V2), discrete(Oade pre, neves, millenia?!)
gain control can be part of amp stage, or pre- or post- attenuator, stepped or swept
metering no meters, clip lite, analog vu, LED bar graph
headphone amp some do, some don't
power supply/batteries runs off of either +6 or +12, so a switching converter is usually needed, sometimes 2 9v's are used for +/- rails
phantom supply a nicety, usually done with another DC-DC convterter, could be a source of noise if done wrong...
output line driver optional, the one in the V2 can drive 1000m of cable, but field tapers will never use that...
many, many ways to do all of the above...first thing is choose the topology of the preamp, what is going to be included.
from there there are lots of designs to start with, helpful app notes (jensen, burr brown, national etc.) that give design
suggestions, work with those, build a prototpye. sound test it, find areas of improvement (fix what's broken!)
spin. retest....find a box for it all...
dunno if any of you were on the diy-hdrec list, a similar group trying to make a hard drive based recorder....a few smart guys on there, but scope
creep killed it...i want this...i want that etc. the only way to get something realized is to limit the scope early, get something working then ADD things
to your WORKING prototype. start simple and embellish. or make a basic model that can be built up in different ways. this can be done as an amp core,
then couple it with your preferred method, power supply etc. maybe make a bunch of small boards that plug together or pin compatible?? maybe do a main
amp board for SS balancing, one main board for XF balancing, then make the power supply, metering, headphone amp and output boards plug into that?
kind of a modular approach...maybe even include space for a *GASP* digital board?