Microphone Selection & Placement - A Quick Reference

One of the most commonly asked questions I get as an audio engineer is regarding what mic to use for a specific application. Unfortunately, there are as many opinions about that question as there are audio techs in the field. There are also about the same number of mics available to choose from. What follows is a compilation of my experience with a variety of mics that are both industry standard and, in most cases, affordable. I’m sure lots of people will want to argue and I’ll hear about all the little nuances and esoteric mics that I missed. Good thing I’m always open to trying new techniques!

This article is very long and meant to be more of a reference than a how-to manual. Please feel free to skip the sections that don’t apply to what you do!

First a bit about the types of mics available. A dynamic microphone uses a magnetic element to convert air vibrations into electrical signals. Because of the density of the magnet, they tend to respond a little more sluggishly and inaccurately with low volume or at a distance, but handle high volumes or sound pressure well. A condenser microphone uses an electrically charged element (condenser is an older name for capacitor) which is much lighter than the dynamic element, so it is able to respond more accurately at low volumes or at a distance. Because it’s a charged element and the signal it produces is very small, it requires a battery or phantom power to operate.

Vocals

There is no “one size fits all” vocal mic because every vocalist has a different timbre that makes mic selection a little more complicated than that. I always suggest that audio techs try different vocal mics until they find one that they and the artist agree on. You can often rent a selection from your local audio retailer and experiment.

The standards in vocal mics are the Shure Beta 58a, Beta 87a and the Sennheiser e835. The Beta 58a is a dynamic that I would not hesitate to put in front of any vocalist and will satisfy just about any tour rider. The Beta 87a is a condenser that sounds better and warmer, but is not for the amateur. It’s pickup pattern requires a consistent mic technique to sound good. The e835 is an equally popular dynamic that would work for any vocalist.

Drums

I have tried a variety of mics and techniques for drums, and the best advice I can give is to experiment when you can, especially with the kick and the snare. My current favorite for kick is the Shure Beta 91a, which is a flat condenser mic that you lay on top of the dampening inside the drum. Obviously, it requires a port for that. Other great options are the Beta 52A or Audix D6, both of which go on a stand and are typically placed at the port (Hint: try different angles and depths as well as placing the mic inside the drum and pointing it at the beater or at the shell.). If there is no port, setting it an inch off the head at the very center is a good place to start.

Touring engineers will tell you nothing beats a Shure SM57 on the snare, but I have found the Sennheiser E604 to be a very good alternative. Just the fact that it clips on makes changeovers much faster than using a stand. A Beta 58a is also a good choice for top or bottom. Place the mic just above the rim (so it won’t touch) at an angle that goes more across the head than pointed directly at it. Using a bottom mic for snare is also a great way to improve the quality of sound because it picks up more of the snare (the metal spring part) and less of the snap.

For high hat and overheads, just about any decent condenser mic will do. I use a Shure SM81, which is an industry standard condenser, on a stand pointed down at the top of the hat. You can also mic it similarly from the bottom. I like the top because I can position it so that the cymbals are between the snare and the mic, which partially blocks it from picking up the snare, and I get plenty of attack. Position your overhead mics so that they pick up a good combination of all the cymbals, paying a little more attention to the ride. It sounds different from the crashes and often has a different prominence in the mix.

There is a huge variety of mics just for the toms. The Sennheiser E604 is a great choice, again for the decent quality of sound and the ability to clip on for quick changeovers. My favorite is the Shure Beta 98AD/C condenser mic. They also clip onto the rim of the drum, though they’re a bit more work, but they sound amazing without having to do much EQ. Don’t put them on a snare top, though, as they can’t handle the amount of sound. They’re a little more expensive than the E604, though not as much as another great choice, the Sennheiser MD 421, which is in the $350 range, but sounds amazing. It’s also used in studios, but it’s affordable enough to use on festivals. In a pinch, a 57 of any flavor will work just fine.

For congas, bongos and similar drums, a good condenser on a boom stand placed over the instrument will work well. Get it as close as you can without getting in the way of the players’ hands. One mic for every two instruments is plenty.

Cajon is a popular instrument for acoustic sets, and works great with a Beta 52A or D6 pointed at the sound hole. Sometimes you’ll want a 57 or a small condenser, like the Shure KSM137 pointed at the front to pick up the percussion of the hands. For Djembe, put a condenser on the top and a 57 inside the bottom (both on stands, unless you can clip one on). The bottom mic gives you the boom and the top gives you the attack or distinction in the notes.

Guitar

For electric guitar amps, the SM57 used to be the standard. Then Sennheiser came out with their E609, a rectangular, side-address mic that you can put on a stand or simply hang over the front of a guitar cabinet by its XLR cable. For $100, it’s the best sounding inexpensive mic I’ve found to put on a guitar cabinet, and it’s all I use anymore. I hear they’re even popular in studios.

If you ever have to mic an acoustic guitar, I feel for you. It’s difficult to get a great sound out of them because of the distance required to keep the mic out of the way of the guitarist’s hands. Put your favorite condenser on a stand and point it at the fret board just off of the sound hole toward the neck of the guitar. That typically keeps it out of the way of both hands and picks up a balance of the “body” (coming from the sound hole) and finger noise. I typically use an AKG C1000s or a Shure SM81. If you can clip a microphone on, that’s even better, because any movement of the guitar will drastically change the sound you get. I haven’t tried the DPA Core 4099 with guitar clip, but I hear it’s amazing!

I always go direct on a bass guitar when I can, but when a mic is called for, a Shure Beta 52A is a great choice and it’s a favorite of many a touring engineer. They often want direct out and a mic to get the nuances of a well-tuned bass cab. The issue with a mic on the bass cab is that you have a high potential for feedback through the subs. If the direct out isn’t working in a festival, try using a good DI, like the Radial J48. Plug the bass into the input and loop the parallel output jack into the bass rig. You’ll get a pretty decent sound at the XLR output.

Piano

There are lots of ways to mic a piano, from a single SM57 above A440 to David Meece’s 7 mic custom setup. I always use at least 2 mics on piano to capture the complexity of the instrument more accurately. The difficulty is that the part that produces sound we want is spread out along the entire width of the sounding board and includes such things as the hammers hitting the strings. Each piano is different in where the sweet spots are. Using a good quality condenser is crucial, and spending more money will achieve better results. Also, insulating the microphone from the body of the piano will reduce unwanted vibrations. A pair of Shure KSM 137s is a decent choice, but I prefer AKG C414 or Earthworks Piano Mic System, both of which are very expensive. Use the best mics you have and experiment with placement to get even coverage.

Big Band

If you are dealing with players that are used to using mics, you don’t need to do anything special for trumpets, trombones or saxophones. A Beta or SM 57 on a stand works great for the volume levels of any of those, and they will control blend and solos on their own. If you want a little better sound from saxophones, especially the smaller ones (alto and soprano), I like a condenser like the Shure Beta 98H/C, which is a clip-on that goes on the bell. It also works for clarinet.

Strings

A good fiddle player will have a pickup system. For fiddles that don’t, and for violins, cellos and the like, a miniature condenser clipped to the bridge works well. The DPA CORE 4099 comes with different clips for a variety of instruments. You can also clip on a miniature mic like a DPA 4061 or a Countryman I2. If you don’t have a suitable clip-on mic, a good condenser on a boom over the violin/fiddle will work, but is susceptible to change with the movement of the player. I have never seen a violin or fiddle player that doesn’t move! For bass or cello, you can put a condenser on a stand and point it at the “f” hole, just be sure to keep the mic out of the way of the bow.

Choir

There is no great way to mic a choir of kids that don’t project. Unfortunately, I know this from experience. I have, however, had great results from using a few AKG C1000s on stands placed evenly across the choir. Any decent condenser will work. Be sure to use tall, quality stands and get the mics placed equidistant from the vocalists and a distance that allows the sound to blend a little before it hits the mic. If you get your mics placed too closely to each other, you’ll get some phase cancellation between the mics when the same sound arrives at each mic at a slightly different time. To avoid this, we use the 3:1 rule: The distance between mics must be 3 times the distance from any one mic to the sound source. This applies to any multi-mic setup (including piano) but is most noticeable with choirs. 

Xylophone, marimba, glockenspiel, bells, vibraphone, etc.

As with a piano, all of these instruments spread out the sound along their entire length. You also will want to pick up some of the attack of the mallets hitting whatever medium makes the sound. With most of these instruments, the initial sound reverberates through tubes mounted below the wood or metal pieces, however you should get plenty of sound by placing two condenser mics on boom stands over each end of the instrument. Be sure to communicate with the musician to make sure your placement is as close to the instrument as possible without being in danger of getting hit by the mallets.

A few more unusual ones

French Horn is a beautiful instrument, and pretty confusing about how to mic it. The best technique I’ve used is to put a Beta 57 (or 58) on a short stand directly behind the player. The way the horn is played points the bell, which is where the sound exits the instrument, behind the player, and usually on their right side. Putting a mic in that space picks it up well.

For flute, the sound is generated at the mouthpiece, so clipping a mic on the other end won’t work. There’s also a significant amount of air going across the mouthpiece, so to avoid the noise generated by that, use a condenser mic on a boom stand pointed straight down directly above the mouthpiece.

Tubas are difficult. I learned my best tuba technique from mixing mariachi bands, and quite by mistake. Take a Beta 58 with a foam windscreen, wrap it in a plastic bag, and drop it down the bell of the tuba until it comes to rest, then tape the cable in place with something like gaff tape that won’t leave a sticky residue on the instrument. Don’t use a condenser mic because the tremendous volume generated inside the tuba will cause it to distort. Alternatively, with mariachi bands that like to move a lot as they play, you can use a clip-on instrument mic at the bell of the tuba attached to a wireless pack. Just make sure you secure it well!