I do almost exclusively classical music, from small chamber orchestras to symfony size.
Generally I tend to use omni microphones whenever possible, simply because I like the sound I get out of them. You have to place them a little closer than cardoids, and they can be a bit picky about room acoustics and it might take a bit more "ear" from the recording engineer. It is definitely worth it though.
For recording acoustic music, I can only recommend small diameter omnis. (Well, some of the really good large diameter mics can make really good recordings, but we are talking a different price level there).
- My current favourite pair is my DPA 4003-s which I am not going to suggest given the price. If you stumble over a pair of DPA4006 though, that is definitely a top-level mic (DPA was spun off from B&K, so B&4006 is the same mic).
- On a little more modest budget you might want to look at Sennheiser MKH20, used they tend to come in at a decent price in USA (new, the USA distributor adds way to much).
- In the Neumann series, KM183 are actually very nice, much better for this purpose than the KM184 which can tend to be a bit on the harsh side. You can make good recording with your 184, but you have to step back a bit from the source, and might still need to EQ a bit.
- Going still lower in price they tell me that the Russian Octava 012 is a good mic, never used it myself though, and the verdict is still out on the Chinese version (there are a number of lawsuits going on between the Russian company and what looks like thieves to me).
- I also have a pair of Studio Projects C4 that comes with both omni and cardoid mics, these are definitely useable, but if possible I would go for the KM 183 instead.
One of my friends swear to God that the best recordings he has ever done was with a pair of DPA4061. These are the ridicuosly small but very good. Maybe a tad on the high side as for self-noise, about the same as Earthworks omnis. For almost all uses this is not going to be a problem, but for very quite sources it can show itself.
There are a few other omnis you may want to look at, but I think they tend to come in at higher prices. Producers such as Microtech Gefell or Schoeps comes to my mind there. The Earthworks mics seems to be loved by quite a few people as well, no personal experience though.
As for mic technique I tend to use simple AB, placing the mics something between 1 and 3 feet from each others, typically around 1,5 feet. Best way to do this is to mount them on the same stand using a stereo rail. Then it is all about placing the mics in the room. A good stand really helps. Although omnis are less sensitive to vibrations, I always mount mine on shock mounts to be on the safe side.
All in all, in that price class I have been very happy with my Neumann KM183 pair.
Gunnar