Bobbsy
Boring Old Git
Well, actually it's pretty impossible to choose a mic just from a specification. For example, I have a calibrated reference mic I use to check acoustics in theatres--it's darn near perfect in terms of frequency response (and "better" than most of my favourite mics) but it sounds really boring if I try to record anything real with it.
To try and answer your question:
Frequency response is important because it reflects how accurately a mic converts sounds in the audible range to an electrical signal. With really good ears, you can probably hear from about 40Hz to 20,000Hz (though as you get older this top number reduces--and the lower number is more a kick in the gut than real hearing. In theory, the frequency response should be flat but, in the real world, mic designers add in peaks and troughs in the response to make the mic better for its intended use. For example, vocal mics often have a peak designed in in the upper mid ranges because this helps a voice cut through in a mix. However, the same peak could make a violin very screachy!
Impedance is only important if the mic is the wrong impedance for the interface or mixer you want to feed it into. Almost all modern microphones are low impedance (i.e. under 600 ohms) with most somewhere in the 50-200 ohm range. As long as the mic you choose is something like that, you'll be fine. Just occasionally you may see some older mics with a higher impedance and this might need matching--but unless you're buying either a cheap Skype mic or an ancient classic, you should be fine.
Sensitivity is exactly what it implies...how much sound level is required to get a certain electrical output. If a mic is very low sensitivity, you may need a specialist pre-amp to get the best out of it, otherwise you end up running you pre amp cranked way up and adding noise. Again, though, unless you get into fairly exotic mics, most will be in a "normal" range. FYI, condenser mics tend to be more sensitive than dynamic mics.
Polar pattern IS an area where you have a choice and a decision to make. For some uses, an omni mic--on which is equally sensitive from every direction--gives a more open, natural sound. However, in a typical home studio setting, this also means you'll pick up a lot more of the "room", including computer fans, air conditioners and the bus going by outside. For this reason, "cardioid" mics are probably the most common pattern to use--these pick up far more sound from one side than the other, meaning that facing it away from sources of noise (like your computer) rejects a lot of the unwanted background. It also means that, if you room is hollow and boxy sounding, you pick up a lot less of this unpleasantness.
By diaphragm, I assume you mean "small diaphragm" or "large diaphragm". Small diaphragm mics tend to be more detailed and analytical in their sound while large diaphragms are often warmer and smoother sounding. However, a really good small diaphragm can sound nicer than a mediocre large diaphragm and vice versa. Typcially, a large diaphragm mic tends to be the first mic when people are getting started--but, as you go on, you'll likely end up with a mix.
To try and answer your question:
Frequency response is important because it reflects how accurately a mic converts sounds in the audible range to an electrical signal. With really good ears, you can probably hear from about 40Hz to 20,000Hz (though as you get older this top number reduces--and the lower number is more a kick in the gut than real hearing. In theory, the frequency response should be flat but, in the real world, mic designers add in peaks and troughs in the response to make the mic better for its intended use. For example, vocal mics often have a peak designed in in the upper mid ranges because this helps a voice cut through in a mix. However, the same peak could make a violin very screachy!
Impedance is only important if the mic is the wrong impedance for the interface or mixer you want to feed it into. Almost all modern microphones are low impedance (i.e. under 600 ohms) with most somewhere in the 50-200 ohm range. As long as the mic you choose is something like that, you'll be fine. Just occasionally you may see some older mics with a higher impedance and this might need matching--but unless you're buying either a cheap Skype mic or an ancient classic, you should be fine.
Sensitivity is exactly what it implies...how much sound level is required to get a certain electrical output. If a mic is very low sensitivity, you may need a specialist pre-amp to get the best out of it, otherwise you end up running you pre amp cranked way up and adding noise. Again, though, unless you get into fairly exotic mics, most will be in a "normal" range. FYI, condenser mics tend to be more sensitive than dynamic mics.
Polar pattern IS an area where you have a choice and a decision to make. For some uses, an omni mic--on which is equally sensitive from every direction--gives a more open, natural sound. However, in a typical home studio setting, this also means you'll pick up a lot more of the "room", including computer fans, air conditioners and the bus going by outside. For this reason, "cardioid" mics are probably the most common pattern to use--these pick up far more sound from one side than the other, meaning that facing it away from sources of noise (like your computer) rejects a lot of the unwanted background. It also means that, if you room is hollow and boxy sounding, you pick up a lot less of this unpleasantness.
By diaphragm, I assume you mean "small diaphragm" or "large diaphragm". Small diaphragm mics tend to be more detailed and analytical in their sound while large diaphragms are often warmer and smoother sounding. However, a really good small diaphragm can sound nicer than a mediocre large diaphragm and vice versa. Typcially, a large diaphragm mic tends to be the first mic when people are getting started--but, as you go on, you'll likely end up with a mix.
