This isn’t the first time we’ve tackled this topic: although recording vocals may seem like a simple task, it may be one of the elements that is hardest to get sounding right. The voice is an instrument with a wide range (in frequency and harmonics as well as dynamics) and, besides, it is one of the sounds our ears are most accustomed to. The voice is full of nuance, and it makes sense that when it comes to capturing it, there are also many details that can make a difference. Mic type, placement, polar pattern, preamp, processing… And that’s only on the technical side. The real difficulty, the truly delicate part, enters the realm of human relationships. It doesn’t matter how well the mic/preamp/compressor/whatever is set up: if the singer isn’t “in the song,” the recording may be technically correct, but it probably won’t be one of those that moves you. We should not forget that records become great when the songs stop belonging to the artist and the listener makes them their own, something that happens only when something touches the person listening.
As Michel Martín pointed out in the vocal recording Master Class covered in another issue of ISP Música, technology should serve the artist, so that he or she is comfortable and can give their best. The goal is to capture memorable, magical moments in which the listener doesn’t notice how the voice was recorded, but rather the soul it carries and what it conveys.
An “ordinary” performance in front of a million-dollar signal chain will not rise above that ordinariness, but an exceptional performance can give you goosebumps and convey thousands of sensations to the listener, regardless (almost) of the mic used. The “almost” refers to the fact that, on the one hand, there is a certain basic quality that has to be met and, on the other, that the same performance, supported by sound technical choices, could have been even better.
So, in this Vocal Recording special, we wanted to address both aspects of recording: the technical and the human. This first part will focus on some of the technical aspects to consider when recording vocals, and the second will move into somewhat more complex territory, laying out ways to use those and other tools to draw the best out of the performer.
Which microphone should you choose?
Probably the best answer to this question is: “Try them.” That’s no joke. When recording vocals, it’s very common to compare the mics available to us beforehand to see how each one responds to the singer’s voice. It’s simple: you set up the different mics side by side and the singer performs a section of the song (preferably one containing the softest and loudest parts of the tune in terms of dynamics) once into each mic. Then you listen to each result separately. There is always one mic that stands out from the rest, whether because it sounds more natural on that voice, has more “air,” makes the voice sit in the track more easily, handles the singer’s dynamic changes better, tames some unwanted aspect of the voice, or the singer “recognizes” themselves better in it… As Csaba Petocz (Elvis Costello, Metallica, Lynyrd Skynyrd) says, the perfect vocal mic doesn’t exist; there are simply different mics for different people.
Take a look at the article “Mic Shootout at PKO,” which details the aspects of this process and lets you compare the response of five exceptional mics: AKG C12, Neumann U47, Neumann U67, Manley Gold and Blue Bottle. If you look at those five, you’ll see that they are all large-diaphragm condenser mics (3/4’’ or more). It’s common to choose this type of mic when recording vocals. At this point we should clarify that a large-diaphragm condenser doesn’t pick up more bass than a small one. In fact, a smaller diaphragm moves more easily and so the mic’s response is more faithful over a wider portion of the spectrum. What does usually happen, however, is that the coloration large-diaphragm condensers introduce can make vocals sound warmer and fuller. Also, because the diaphragm surface is larger, the sensitivity of this type of mic is usually higher (compared with a smaller diaphragm).
As for other types of mics, ribbons usually have a frequency response that generally doesn’t extend as high as condensers, which can be very desirable for giving the voice a certain character.
We shouldn’t forget that before the first condenser mics appeared (the U47 was the first multipattern one), the norm for recording vocals was to use ribbon mics, so using one can give the vocal sound a certain retro touch.
Recently, however, Royer Labs, widely known for its ribbon transducer designs, released the first active ribbon mic on the market (the R-122). Using phantom power, the mic delivers a higher output level and presents an ideal impedance, which widens the number of preamps it can be used with (typically, when a ribbon mic is used to capture sources with moderate SPL, you need a preamp with high input impedance and a lot of gain). This mic may offer precisely the best of both worlds; time will tell.
And as for dynamic mics, they shouldn’t be banished from these duties either. Sometimes a dynamic provides just the right punch for the voice. If you want examples, listen to Kiss’s album Sonic Boom. Paul Stanley’s and Gene Simmons’s vocals were mostly recorded with an SM7. Anthony Kiedis’s (Red Hot Chili Peppers) vocal sound is also often achieved with an SM7, singing very close and with a lot of compression. This Shure model is very common when a dynamic is used for vocals, because of its frequency response, which is more extended than usual for a dynamic but without losing the character of one. “If the expensive mic doesn’t work, try an SM7; you may have to EQ a bit, but some singers sound better on it” is something many engineers and producers say regularly.
Other things that can help you decide on one mic or another involve using its frequency response to shape certain aspects of the voice. For example, a voice with little body will benefit from a mic that adds some, and vice versa: a very low voice will do better with a mic that doesn’t boost that area. Similarly, a somewhat shrill voice will get along better with a mic that doesn’t boost the upper mids, while a dull voice will benefit from it. Some mics can accentuate a particular singer’s sibilance, another aspect that can be decisive in ruling out a suitor.
So, once it’s clear what to expect from each type of mic (in terms of the transducer), don’t be afraid to try several options. Let your ear be the judge.
Polar pattern
Starting again with the most common, the polar pattern most often used when recording vocals is cardioid. On the one hand, it offers an off-axis response that allows the singer some freedom of movement (and expressiveness) without the mic’s response varying too much. On the other, it lets you play with the proximity effect inherent to this polar pattern to add more body to the voice.
The proximity effect results in a boost of low frequencies in directional microphones (those that operate on pressure gradient) when the sound source gets closer to the mic. So, depending on the singer’s distance from the microphone, its bass response varies, and this can be used to advantage to bring different nuances to the voice. However, this same trait can be harmful in some cases. For example, when the singer likes to sing very close to the mic and the proximity effect is exaggerated, or when recording several vocalists, if you use distance from the mic to balance the levels of the different musicians, the response of their voices can be distorted. In these cases, using an omnidirectional pattern eliminates the proximity effect and with it the issue of the mic’s response changing with the distance to the source.
Keep in mind, however, that with the mic in omni, more room sound will be picked up (the cardioid has a null at the rear that the omni lacks), so the voice may not sound as close. One way to alleviate this “side effect” is to place absorbent material behind the mic to keep room sound from reaching it from that side. Devices like the Reflexion Filter are very useful for this.
As for tighter polar patterns such as supercardioid or hypercardioid, they are very suitable for keeping other instruments from bleeding into the vocal mic when recording with several musicians at the same time.
Tube or solid state? Preamp?
There is also often some confusion at this point. It is often believed that tube microphones are better than solid-state ones. That is not true: if they are well built, both will be excellent mics. Of course, one may be better suited to some cases and the other to others.
Tube mics usually add a certain color that solid-state ones don’t have. People usually talk about smoother, more nuanced highs and a “body” (the result of the harmonics the tube introduces) that can make the mic ideal for some types of voices or songs… but also unsuitable for others. Some songs don’t call for a voice with these characteristics, and in those cases a non-tube condenser will be more suitable. Or the voice is precisely too aggressive and the tube can soften it a little. As said in the previous section, the best thing is to try what works with that singer on that song.
When it comes to choosing the preamp, something similar happens as with mics. Once you’ve chosen which microphone to use, it’s not unusual to try several preamps to see which works best (and once you have a mic-preamp pair, move on to trying different compressors, etc.). However, when pairing the mic with a preamp, it is generally kept in mind that if the mic is a tube mic, it shouldn’t be connected to a tube preamp as well. Introducing that element at both stages of the chain can exaggerate its effect too much.
As for impedance matching, with dynamic and condenser mics it isn’t desirable for the mic’s output impedance to equal the preamp’s input impedance, since this reduces level and signal-to-noise ratio. A suitable ratio is usually around 1:10 (the preamp’s input impedance about ten times the mic’s output impedance), but in reality practically any mic you’ll find in a professional studio can be used with any preamp.
Have you tried those preamps that let you vary the input impedance? In theory the feature is aimed at ribbon mics, but in practice it’s useful for any type of microphone. By varying the input impedance you change the mic’s timbre and response without touching an equalizer… when you try a mic through different preamps, pay attention to that kind of effect.
By the way, if your preamp has this knob for varying input impedance, don’t be afraid to try the variations it can produce in the mic’s response; you may find very pleasant surprises that would be very hard (or impossible) to achieve with simple EQ.
First adjustments
Once you’re 100% satisfied with the result of the mic-preamp tandem, a bit of EQ and compression can help settle the voice into place.
During recording, light settings are usually used; the goal at this stage is usually to add small nuances that build up, leaving the more aggressive processing for the mix.
Unless the singer has a very low range and reaches notes (frequencies) very low in the spectrum during the song, a high-pass filter will normally help bring clarity to the voice, eliminating possible low-frequency noise problems transmitted to the mic through the stand or cable.
If you have a high-pass filter on both the mic and the preamp, it’s usually better to use the one on the mic, to eliminate the unwanted material as early as possible and keep it from even reaching the preamp.
As for EQ, think of applying boosts/cuts of just a few dB (2-3) on the equalizer to shape or enhance some aspect of the voice. If you find yourself having to EQ more than 6 dB to fix a problem, it’s time to rethink the chosen mic and preamp (or the singer). That said, it isn’t unusual to need a notch filter to remove an unwanted harmonic (if you insert it as a plug-in, you can always remove it later). Of course, if you’re clear about the sound you’re after, don’t be afraid to go for it and record it directly. The advice we’re giving leans toward the cautious side, which leaves more possibilities open for the mix.
Besides using a pop filter, problems with plosive consonants can be softened by slightly varying the mic’s position, so the diaphragm isn’t perpendicular to the blast of air. You can rotate the mic so it points to one side of the mouth, or above/below it. In those last two cases, keep in mind that you’ll increase the nasal sound (pointing up) or the chest sound (pointing more toward the chest). This technique of slightly varying the mic angle can also fix problems with “s” sounds. However, be careful how the mic is positioned relative to the singer, so they don’t have to sing in a strained position. Although you will have seen in many studio photos the mic placed above the singer, with the singer having to tilt their chin up to sing, that position isn’t right for all singers. It’s better to ask the performer how they’re most comfortable and position the mic accordingly.
If you find that, for technical reasons, the mic has to be placed in a way the singer doesn’t find comfortable, you can use the pop filter to disguise that position. The singer usually takes the pop filter as a reference for where to stand, so you can place it in a way that suggests the mic is in the position that’s comfortable for them, while the mic behind it is actually placed differently (as long as a very tight polar pattern isn’t being used). In these cases it’s more convenient to put the filter on a separate mic stand. This makes it easier to place the filter in more extreme positions and, at the same time, avoids transmitting noise to the mic (many engineers put the mic on one stand and the pop filter on another by default).
As for compressors, when used in recording they typically apply gain reduction of about 3-6 dB, with attack and release times that aren’t too aggressive. Again, the goal is to establish light control rather than an exaggerated compression effect during recording.
However, as we’ll see in the second part of this series, what gets recorded to tape/hard disk is one thing and what is sent to the singer’s headphones is another… (more details on compression and other techniques in the next article).