Let’s begin with what you won’t see in this article: You won’t find the customary list of mics, their governing attributes, or a list of instruments they flatter; mics age differently, making that kind of list largely moot. Also, it wouldn’t necessarily help if you didn’t have those microphones, many of which are quite expensive.
Likewise, you won’t see a right-brained crystallization of concepts you’d come across in a book such as, “Mixing with Your Mind.” Michael Stavrou does that better than I could ever hope to.
Instead, we’re going to cover basic concepts, as well as some tips, tricks, and considerations that have worked for me over the years.
Learn the Basics (and Hopefully More) of the Microphone
Later we will consider factors arguably more important than the microphone. But still, a basic understanding of microphones will help you get quick results.
In all mics, a transducer converts soundwaves into electrical energy, though different design principals in the capsule engender different results. Simply speaking, you’ve got:
Dynamic (Moving Coil)
A coil is affixed to a membrane (called the diaphragm), vibrating in opposition to a surrounding magnet, transmuting a soundwave into electrical current. These mics tend to be quite robust on stage, can handle a good deal of loud transients, tend to be especially resonant between one and 4 kHz, and often roll off high frequencies above 10 kHz or so. They’re often used on drums, live vocals, and guitars.
Ribbon
Like a moving-coil capsule, a ribbon uses a membrane, but this one is very thin—say the equivalent of a tiny piece of foil—which vibrates in the middle of a magnet. Ribbons tend to be more accurate than moving-coils, but also more sensitive, and can be damaged by the implementation of phantom power. It is said that their “resonant peak” occurs at the bottom of their range, securing a flatter frequency response afterwards. They can also be flattering on instruments with natural high end.
Condenser
Here you’ll find two conductive plates at work, one acting as the diaphragm, vibrating with the sound source, and modulating its distance between the other plate. This motion varies the capacitance and voltage of the resulting signal. Condensers require external power to run and, due to their construction, tend to have specific colorations, particularly in the highs and high-midrange. Often, you’ll hear them on vocals, where they engender the present, silky sound we’ve come to expect in pop.
There are subcategories of course, and uses vary across makes and models.
Next, We Have Polar Patterns
Omnidirectional
Sound is captured all around the capsule.
Cardioid
Sound is captured in a heart-like pattern around the microphone, with minimal response (if any) coming from the back. There are variations and substrata of Cardioid patterns, but we don’t have the space here.
Figure 8 (Also called Figure of Eight or bidirectional)
Sound is picked up immediately in front of the capsule, and immediately behind it, with virtual rejection on the sides. This polar pattern can be quite useful when trying to get separation among live instruments.
Go ahead and do more research into these concepts, since drilling information into your head will help you avoid making catastrophic mistakes (like running phantom power through a ribbon microphone), and will aid in situation-specific circumstances (singer/songwriter wants to play guitar while singing? Two figure-8’s please!)
Consider the Considerations
With technical knowledge in hand, here’s what I consider when pairing a mic with an instrument.
The Instrument
An instrument’s characteristics will have a huge effect on how I mic it. I don’t mean the instrument itself, but the way the instrument expresses itself: An acoustic guitar can be extraordinarily bright, or quite dull, depending on the make, the model, the strings used, and of course…
The Player
There’s a classic story in which Charlie Parker may/may not have pawned his sax right before an important gig. Either way, he used a plastic saxophone for Jazz at Massey hall. What did he sound like? Charlie Parker. People have their unique timbre. Use your ears to hear what’s different about the player you’re miking, and react accordingly.
The Room
The room is quite important, maybe more so than the mic itself. If you’re in an unfamiliar room, walk around while clapping your hands, listening for flutter echoes. Use the higher and lower registers of your voice to test out low-/high-frequency responses. Once you find a pleasurable spot, set up there: You’ll be more inclined to use the sound of the room to your advantage, using off-axis positioning with confidence.
The Track
The track itself will dictate how you’ll want to work. If you’ve heard the demo, you’ll have a good idea of harmonic motion, arrangement, and genre, which will influence your decisions. For instance, in a pop track, I might not put a ribbon microphone on a singer, because today’s pop tends to require a bright, sparkly sound out of the vocal. However, on a rock track, a dynamic or a ribbon might just be the ticket.
The Function
What’s the instrument doing in the track? Is it providing percussive elements? Or is it laying down harmonic pads? This will influence mic choice and placement as well.
Now that we’ve got our concepts and considerations, here’s…
A Miscellaneous Grab Bag of Tips!
Know thy voice, know thy mic
If you’re trying to get a good sound, it always helps to have a reference you can count on. To judge a new monitoring situation, I run a record I’m deeply familiar with through the system and run it through the “childhood test” (i.e., does this record sound like my childhood? If not, what about it sounds different from how it sounded in my childhood?). For microphones, I have my voice. I know it well from listening to it in singing and voice-over contexts. I can judge a microphone’s innate qualities by seeing how it stacks up to my own voice, because I know what to expect from my recorded voice. I can use this knowledge to assess any microphone I’ve never used before. Does one make my voice sound (even) more nasal than another? Does another add low-end? This will be good information for utilizing a microphone.
Avoid putting a mic right up on the source—unless you have to
If you need to overwhelm to contain leakage, that’s one thing. Otherwise, sounds benefit with a little bit of air, especially in a great space.
Use the proximity effect to your advantage
The closer you get to a microphone, the more low-mid range you’re going to elicit. If your instrument could use more 300 Hz or so, bring the microphone in.
Big picture drums
When miking a drum kit, I would try to achieve a good overhead sound first, and then fill in with spot mics.
Use a figure eight to reject sounds you don’t want
The sides of the mic are virtually dead. Thus, you can angle the microphone in such a way that anything on its sides are out of the line of fire.
Think polarity, but go for character over polarity
People obsess about getting their signals in solid phase cohesion. This is good practice, but it should never be at the expense of a characterful sound.
Before recording an instrument, tune it extensively, and if it’s a string instrument, tune it multiple times. It needs to settle into its intonation.
Stereo or Mono Miking?
In my opinion, the answer lies not in the instrument, but in its function. If your piano is the big feature of the song, then a stereo spread might be suggested. If it’s one of many harmonic instruments, mono might be preferable.
If the sound you’re miking is natively harsh, try pairing it with a mellower mic, and vice versa
There’s no sense putting an innately shrill mic on something like a trumpet—there’s a reason that many jazz records utilize ribbon microphones.
If you’re taking a DI with an electric instrument’s amp, check the polarity between the two signals up front
This way, you’ll have your sound ironed out before the mix process, and putting it into the track might be as simple as putting up the faders and blending the sound.
Try turning the mic off-axis to get mitigate particularly harsh sounds
This tip is great for project-studio operators with a small microphone locker. If you find yourself consistently, aggressively de-essing vocals you’ve recorded, try placing the capsule at a slight angle to the singer. The same goes for a piercing brass instrument or an alto or soprano saxophone. This can cut the harshness, but at the same time, it teaches you to utilize every part of your microphone—not only a valuable exercise, but a way to add variety to the sonic palette.
That’s all the space I’ve got. B&H has plenty of video tutorials for specific miking techniques. And as always, feel free to leave a comment if you have a specific question!