I am looking for a good microphone to record a piano. This is whole new field to me. I looked in the Internet and I found a few places stating about what I shouldn't buy, like, dynamic range microphones.
What characteristics should I look for when picking a microphone (or set) to record a piano?
Would recording directly from a digital piano give me a better quality (although with less dynamics possibilities)?
Microphone capture mechanism
The piano has a very wide frequency range, so you might want microphones with a wide and accurate frequency response. I say "might" because it depends on what sound you are looking for. If you need a more opaque sound (with less highs) then using a microphone that rolls off the higher end of the spectrum could be a good idea.
If you are looking for an accurate capture, then dynamic microphones (do not confuse dynamic mics with dynamic range, like you did in your question, they are not the same thing) are out of the question as they tend to have a not-so-good frequency response in the highs (again, which could be good if you are going for that sound, but not very good for accurate recording).
Instead you should look for condenser microphones, or ribbon microphones (the later only if you know what you are doing, ribbon mics are very delicate). Both tend to have better frequency response than dynamic mics, and also tend to have a flatter frequency response in general.
Polar pattern
Depending on the room and piano type, you'll get different results with different polar patterns. Omnidirectional mics will capture more of the room's reverberance, which can be good or bad depending on your scenario. Cardioid mics will capture less reverberance, and they are also prone to the proximity effect, which is important to consider if you are going for close miking (and again, could be good or bad depending on what you are looking for).
If you are not recording in a professional scenario (in a studio with good sound treatment), then the safer bet is the cardioid mic. You can also get a mic with switchable polar patterns, that way you can test which one you like the most.
Number of microphones
The piano also has a wide stereo range. Highs come from one side, the lows come from the opposite side, the mids come from the center. If you want to capture this, you'll need more than one mic to implement stereo recording. To do this accurately you need two identical mics (same model).
Would recording directly from a digital piano give me a better quality (although with less dynamics possibilities)?
It depends. If you don't know what you are doing and you are not recording in a professional scenario and/or with the help of a professional, then using a digital piano (or any good sampler) will most likely bring better results.
But you still need to be very careful. Not all digital pianos (and samples) have good quality sound. Not all keyboards can accurately capture a performance, and not all keyboards have the same key feel (weighted, semi-weighted, etc).
You want a good keyboard, with a good sound engine (on-board sound engine, or using a plug-in instrument). For a sample-based solution, I really like Native Instrument's Definitive Piano Collection. For a physical-modeling solution, I like 4front's True Pianos. There are many other great options out there, but be careful since it's very easy to get a not-so-good one.
Rather sadly, you'll probably get better results from a good digital piano than from microphones on a real one. Unless it's a really nice piano in a really good-sounding room. You'll have noticed I didn't say "and really good microphones". They matter, but not as much as you might imagine.
If you're after "classical" solo piano sound, record stereo. But remember, an audience normally sees a piano on a concert stage sideways on, from quite a distance. In this case "stereo" will be about placing the instrument in a reverberant space, not about "low notes to the left, high notes to the right". This is a mistake made by the sound sets of many digital pianos.
But you will probably not get the results you want from hiring a concert hall and putting a stereo pair in the best seat! You'll fake the stereo ambience from some combination of close and medium-distance micing, and artificial reverb.
I'll get shot down for this, but I've made some very pleasing acoustic piano recordings with a pair of Shure SM57 dynamic mics. And you may be in a position to try this, with no immediate expense! Do you live in a world of modern performing musicians? Grab a couple of SM58 mics, take the balls off - they become essentially SM57s. (Don't drop them though!).
If you have no gear at all, there's another approach. Buy a Zoom H4n or similar, put it on a stand in front of the piano. You'll be surprised how close the result is to a recording made through much more expensive gear. And even if you progress to more sophticated equipment, a good portable recorder is always useful.
They matter, but not as much as you might imagine. That's very misleading. Differences among microphones can be huge, as in night and day.
Commented
May 29, 2015 at 13:45
This is a mistake made by the sound sets of many digital pianos. Perspective is a design choice. Why would you limit yourself to one scenario? Yours only applies if there's only one row perpendicular to the piano, anyway (is there an auditorium with those characteristics?). Even if the piano is sideways, rows other than perpendicular one will get the notes with a panorama difference. Not only that, but in most situations the piano is amplified using microphones, in which panorama is (again) a design choice and not limited by the situation and/or position.
Commented
May 29, 2015 at 13:54
Unless you really want to become a sound guy, just get a Zoom device.
They're about the only simple way to record an acoustic piano.
Like http://www.sweetwater.com/c733--Zoom--Recorders
Seriously, there is just too much physics to figure out.
The recording pattern and style of microphone are valid points, as mentioned above, and will help you to work out how you are going to mic up the piano. In this day and age you need to work out what you are recording into. Most microphones have an XLR output and unless you have some sort of interface then this can be very tough. If you are recording into a mixer, this will likely take your xlr input and you can then direct the signal from there. A lot of the time these days people are opting for USB technology for their mics. Some audiophiles baulk at the idea of using USB, but the tech has come a long way.
I'd go for good omnidirectional small diaphragm condensor mics without excessive brightness in close proximity to the piano (which means that the effect of the polar characteristic capturing more of the room will be at best mildly relevant). The size of the piano means that cardiod microphones would have to be placed at considerably more of a distance in order to get a balanced sound quality without proximity effects and off-axis coloring (off-axis coloring becomes a mostly moot issue even with cardioids once you spring a few thousand dollars/euros for your mics but not everybody has that sort of small change).
Personally, I consider Oktavas a reasonable deal in that problem space. The somewhat more expensive equivalents from Røde I haven't tried (S55 I think?), but the frequency responses I see on paper are more brilliant than I care for for my use case of accordion, admittedly an instrument that is quite less appreciative of additional brilliancy than most pianos are.
