(Proximity Effect, Mic Types, Pick-up Patterns and More)
Recording Vocals in the studio can be one of the most challenging aspects of tracking and music production. Not only does the type of mic affect the quality, but so does the placement, the surrounding acoustics, the room, the polar pattern on the mic, etc. This tutorial will be of assistance to shed some light on these topics, and particularly useful for engineers working in home studios. The mic’s we use today are direct descendants of early telephone technology. Once radio broadcast and recording technology started to emerge in the mid-20th century, music lovers looked at developing better, more specific microphones for use in the studio and recording world. Today, we have an endless variety of microphones to choose from, however, they all still work according to the fundamental principles developed by our techno-ancestors.
There are three main types of microphones utilized in modern recording: Dynamic, Condenser, and Ribbon. Of these, Ribbon mic’s are the least used. I’ll get into some theories regarding Ribbon mic’s and their lack of usage in the studio at a later date. For now just know that their fragile nature has kept a lot of engineers away from using them. When it comes to day-to-day recording, Condenser and Dynamic microphones keep the world going round, and are a staple in studio’s as well as live tours. Even though there are many differences in “how” these two types of microphones work, it can be as simple as whether or not the microphone needs “power”. Dynamic mic’s don’t need any type of power connection, just plug them into a mic pre-amp, crank up the gain, and you’re ready to go. Condenser mic’s require +48V (Phantom Power).
Dynamic Mic (Shure SM58) • Condenser Mic w/ Power Supply (Neumann M147)
There are two ways you can get “power” to a Condenser mic, either it has a dedicated power supply that comes with the mic, or you can use your microphone pre-amp to power it via the +48V (Phantom Power) button. I can’t think of any mic pre-amp, or console, that doesn’t have a +48V button. They serve the sole purpose of allowing you to “power” condenser mic’s that do not have their own power supply.
DAKING Mic-Pre One - notice the Phantom +48 button on the lower right corner
When you use any condenser mic that doesn’t have a power supply, simply connect the mic with an xlr cable to your pre-amp, turn on the +48V button, then start increasing the gain to desired taste. As with all equipment, be careful when powering the unit on. Make sure the gain is turned down and the +48V button is OFF when first connecting the mic as well as disconnecting it when you’re done. The same goes for an external power supply.
Aside from the type of microphone you decide to use, you have to keep in mind something known as Polar Pick-Up Patterns. Pick up patterns refer to where and how the microphone is picking up sounds around it. Facing the mic in the appropriate direction at your sound source has a lot to do with how good the recording sounds. Seems quite simple doesn’t it. But, as with all simple things I can be sure it’s gotten the best of all of us at times. There are several different pick up patterns such as Cardiod, Omni-Directional, Super-Cardior, and Bi-Directional.
Bi-Directional (Figure 8)
Are you confused yet? I have to admit that when I first picked up a microphone (it was a magical, far-away place, known as The 90’s) I was very confused as to what I was supposed to do with this info. As it turns out, it’s quite simple. All microphones have a “front”, either the top or side of the mic depending on the model. When you, or your sound source, is facing the front of the mic, draw a heart shaped loop around the front of it, this is where you are picking up sound. Any sound from the back or side of the mic, that isn’t within the Cardiod pattern will be rejected and not come through clearly. This is known as being on-axis. If you wanted to pick up sound from the front and the back of the mic at the same time, equally, this is where a Bi-Directional pattern would come in handy. Also known as Figure 8, Bi-Directional allows you to record two different sound sources facing either side of the mic. This can come in very handy when recording a duet with two singers facing one another. For those rare occasions where you have lots of people, or things, in a room and they all need to be recorded, you might want to use an Omni-Directional mic. As the name might give away, Omni (all) refers to a mic that can pick up everything around it equally, from all directions. As you can see, the Polar Pick-Up Patterns refer to how the microphone can be positioned to capture the best sound.
To be very honest, the most widely used type of mic’s for sensitive studio recoding is a Condenser mic with a Cardiod pick-up pattern. They provide accuracy, detail, and precision in control, making them easy to use and very effective for isolating sound sources such as vocal, drums, acoustic guitars, piano, etc... If your budget permits, you could go with a variable pattern Condenser mic which allows you to change the pattern the mic is using. This feature provides versatility if you know you’ll be using various patterns in your recording life but it comes at a premium as they tend to be more expensive than a mic with a fixed pattern. Dynamic mic’s (with a Cardiod pattern) are the most widely used mic’s in the live sound and performance world. They are very versatile, clean, and very plug-n-play since they don’t require Phantom Power. They can also take quite a beating without affecting their performance where as a Condenser mic is much more sensitive and would probably break under most live sound conditions. They are also widely used in recording very loud sources such as drums and electric guitar or bass cabinets.
Once you have your microphone set up and plugged in, you should take a few things into consideration. Based on what you know about polar pickup patterns, you know that sound will be coming at the front of the mic, but, you have to also recognize that the mic will pick up ambient noise from within the room or environment. It can really get in the way of a good vocal sound when you are picking up ambient noise, so it is a good idea to try and minimize this. Some very basic sound isolation techniques can really make the difference between a good clean vocal (or instrument) sound or one that sounds like it was recorded in a living room.
We already know that any sound directed at the front of the mic will be the most audible, so, it’s a good idea to make sure the area behind the singer or musician is well isolated and not reflecting any “extra” sounds. A really affordable and quick way to achieve this is to put up blankets on the walls. Some people have even used rugs the same way. A typical wall inside the average family home is not usually the best at sound isolation, especially if the floors are tile. The drywall and tile reflect the sound so much it can sound like a hollow box. Use some blankets and line the wall behind the singer, as well as any tile underfoot, with carpet or blankets to reduce the amount of ambient noise from behind the singer. I have often heard people say “Why don’t my recording sound like those on the radio?” The answer is often the lack of understanding of how sound and microphones work together. The main goal is to try to capture a pure performance in the way we want the audience to hear it. If other sounds blend into the recording it tends to diminish the impact of the intended sound.
An example of how extra sound isolation can help eliminate unwanted spill-over and help capture a more accurate sound.
Photos courtesy of primacoustic.com
It’s fair to say that vocals are one of the key elements of any song, and particular attention is usually focused on getting them to sound “right”. Due to the attention the vocals always seem to get, a lot of people have focused on the equipment side of the equation, often stating that simply getting a “better” mic will fix all of their problems. I believe that having a “better” mic in a noisy environment will only yield “better” noisy results. A better mic will often times pick up more of the background ambiance therefore having the opposite effect. You will get better results in recording by focusing on the environment and sound isolation to complement the microphone rather than buying a more expensive one. Sometimes, all it takes to liven up the vocal is creating a better recording space for the mic by blocking unnecessary sound reflections coming from the back of the mic.
We've already established where a Cardiod mic picks up the main body of sound, but in reality, sound from the back of the mic, or room ambience, can still be captured by the mic due to room reflections. This is why in recent years VoxGuard type shields have become very popular. They are mounted to the mic stand and create a barrier around the back and side of the mic: instant awesomeness! I recently had a singer I’ve worked with for over 10 years, in countless “major” studios, tell me how the vocal we captured in my control room was the best she’s ever heard of herself. We used the same mic (she has her Neumann M49: must be nice) every time and wound up with just as good a result in our control room using a VoxGuard as we did by paying $500-$1000 per day to be in a major studio. There are several different manufacturers making these sound isolation tools, or you could make some yourself with some wood, screws, foam and fabric.
One of the last things often overlooked in this whole equation is how Proximity Effect will shape the tone of the sound. You can look up a great technical explanation on Wikipedia, but for us music makers, Proximity Effect is noticeable as the sound gets “boomy” the closer it moves to the microphone. Basically, all microphones become more “sensitive” and “boomy” the closer the sound source is to the microphone. It takes a lot less energy to move the microphone capsule when the vocalist is right in front of it as opposed to standing 1 - 2 feet back from the mic. Also, there is a noticeable overdrive to low frequencies. Even a “good” mic can produce poor results if proximity effect is ignored. I recently asked 3 time Grammy Winning Mix Engineer John Frye what the biggest mistake he sees in songs he is given to mix, his response: Too much muddiness on the low end due to improper microphone & space usage. Most people will try to fix the sound with an EQ or Compressor. While that might sound good for the moment, it make it much more difficult to mix in context with the rest of the finished production. An easy(ish) way to deal with proximity effect is to position the pop filter with enough distance away from the mic in order to prevent the singer from getting too close. There is a good chance you, as the engineer, might have to remind the singer to step back and not lean into the mic too much. It will happen.
There is a point that I believe needs to be addressed primarily regarding vocalists (sorry to pick on you guys). A drummer has drums, a guitarist has a guitar, but never forget that a singer has a microphone. The mic is the singer’s “instrument” as much as the piano is to a pianist. A lot of times, especially with lesser experienced singers, the “best & most expensive” microphone in the closet is not the best to use. It won’t do them any favors and in fact might over-emphasize unpleasant nuances. These can all be worked out with practice and rehearsal, as long as you can get them to stop tweeting about it and actually do it. Every major record label producer I’ve ever worked with is super demanding of singers, sometimes much more than the rest of the musicians, because the vocals can make or break a record. Nobody wants to hear a great sounding record with bad vocals, so I encourage singers to practice their parts as much as their “instrument”. Even if you never record you practice, try to practice singing into a “hot” mic while listening to it on headphones. You will start to notice how you can change the dynamic, tone, and shape of the sound simply by modulating your vocal amplitude as well as positioning in front of the mic.
I encourage each of you to learn singing your songs from beginning to end, mistakes and all. I have watched professional singers spend days working on a vocal in “parts”, one at a time, and then have to learn to sing the song over again when it comes time to perform it live in front of an audience. Yes, you can punch-in one line at a time, or one word at a time, which is great when it comes to fixing mistakes, but don’t treat the entire vocal part as a mistake right off the bat. You’ll find that the more you practice and know your parts from beginning to end, the less mistakes you’ll make throughout and won’t have to worry about punching in one line at a time. The circle of life is complete.