Building the Right Vocal Chain
When discussing a vocal chain, one scientific (yet not audio-related) phrase should be kept in mind. That phrase is “Order of Magnitude.” Each successive stage in the vocal chain is an order of magnitude, or approximately 10 times less important than the one before it.
In terms of the vocal chain, the importance of each item in the chain works this way:
The first item in the vocal chain isn’t, as you might expect, the microphone. It’s the singer. Why? Because the singer is the source of the sound. Everything else in the chain is there to capture and manipulate the vocals. However, since choosing the singer is beyond the scope of this article, we’ll start our discussion with the second item in the vocal chain: the microphone.
Choosing the Right Microphone
While all types of microphone designs have been used on singers over the years, if you were to choose one mic for vocals, it should likely be a large-diaphragm condenser. It’s not that you can’t use ribbon microphones or dynamic microphones for vocals, but those designs tend to be most usable when (A) you want a specific sound or (B) your singer simply sounds better with another style of mic within the context of the project.
There are dozens (if not hundreds) of large-diaphragm condensers available today, so choosing the right mic for your vocal chain will take a bit of research and some knowledge of who you’re most likely to record. Some microphones are notable for the warmth of their low end, a sound most associated with vintage Neumann tube microphones like the U47. Others are celebrated for the high-end sweetness, or “air,” characterized by the equally vintage AKG C12 (and the contemporary designs based on it). A dark voice without a lot of upper-register information may well benefit from a brighter vocal microphone, while one with a bright or screechy voice might do better with a mic that has a bit more heft in the low register and a smoother top end. A certain amount of knowledge can be gained by looking at frequency-response charts, which are typically available on manufacturers’ websites. But ultimately, each voice is unique; it might take a little experimentation to find the “best” microphone for your needs. Fortunately, Sweetwater’s return policy makes this experimentation possible…
Choosing a Preamp
To begin with, look for a preamp with a good amount of gain plus enough headroom that the preamp doesn’t distort — even on the loudest notes. If ribbon microphones may be in the mix, this could mean mic preamps with 70dB or even 80dB of gain. With condenser microphones, 30–40dB of gain will typically be just fine. The main thing, though, is to make sure that the output of the preamp isn’t distorted and that you’re not overloading the input of your workstation. Your 24-bit DAW has a theoretical dynamic range greater than the (theoretical) 96dB available on a 16-bit CD, so there’s no need to slam the input of the DAW; you can always turn up the vocal. While it’s true that you can turn up the recorded track, you’ll also be bringing up any noise that was in the track when you do so, whether that’s a grounding issue causing a 60-cycle hum or a tube somewhere in the chain that’s a little noisy. It’s for this reason that microphones with low self-noise and very quiet preamps have gained in popularity.
Clean or Colored?
There are numerous companies building preamps designed to be as transparent as possible — they’re aiming for “straight wire with gain.” These preamps are generally transformerless (even the highest-quality transformers will cause a small but measurable change in the signal passing through them) and use a minimalist circuit design in an effort to leave the signal passing through them unchanged apart from level. Other companies embrace the designs of the past and the sonic footprint of those designs, though generally modifying the vintage schematics to meet the needs of contemporary audio production. Tube preamps would seem to fall into the “colored” preamp category, but well-designed tube preamps can be as clean and uncolored as a well-designed solid-state preamp.
While opinions abound, the reality is this: once you’re dealing with the wide range of well-designed and well-built preamps, the difference between them isn’t really “night and day”; it is, as a wise man once said, “more like the difference between 5:30 and 6:30 in the evening.” This doesn’t mean that all preamps are the same or that you won’t hear a difference when comparing two or more preamps. But, in the greater scheme of things, the preamp will not be the difference between a great vocal track and a mediocre vocal track.
The last few years have seen somewhat of a renaissance when it comes to hardware-based compressors and limiters. The range of options is truly amazing. Choose between tube or solid-state signal paths and optical, VCA, FET, or tube (Vari-mu) gain-reduction circuits. Some compressors allow great control over the variables involved, while others are much simpler to operate. Compare the Tube Tech CL 1B to Universal Audio’s LA-2A, for example — both are marvelous vocal compressors, though the CL 1B offers an amazing amount of control over the various parameters while the LA-2A is much easier to operate, with controls only for Peak Reduction and Gain.
For tracking vocals, though, the main consideration is this: If you’re not sure where you want to end up, then don’t do something irrevocable when you’re tracking. When recording a singer, if you’re smashing the vocals with so much compression that every breath is as loud as the singer’s notes, every consonant causes the compressor to overload, and you can hear the singer’s clothing rustle when they shift position, then you might have trouble making it fit into a mix that requires dynamics. Instead, treat the tracking compression as a first stage. You need to control peaks so that you don’t overload the input of your DAW and for the quieter lines to be audible. But, at the tracking stage, you should work on making the voice sound like a voice. It’s easy to add more compression during the mixing stage of a song; it’s really hard to remove it.
To EQ or Not to EQ
Should you use an EQ when tracking vocals? It really depends — it’s certainly not necessary to do so as a general rule, and many engineers feel that the right choice of microphone can minimize (or eliminate) the need for EQ in a tracking situation. Remember the “Order of Magnitude” theory? If you’ve chosen the right microphone for your singer, the right preamp for that microphone, and an appropriate compressor, then the EQ shouldn’t be that important in the greater scheme of things.
Nevertheless, should you feel the need to EQ when tracking, consider starting with a highpass filter and rolling off those frequencies that are out of the vocalist’s range; this can be as low as 50–60Hz for bass singers but as high as 150Hz for a female singer. The goal when highpassing a signal is to minimize those sounds that could make their way into the recording though you’d rather they not — air-conditioning rumble, the singer’s footsteps, even low-frequency vibrations coming up through the floor and the mic stand to the microphone.
Beyond the highpass though, additional EQ would depend on the specific situation, and no generalization will help — except this: a light hand with the EQ when tracking will usually make the mixing process easier. Drastic boosting or cutting of any frequency tends to mean that the wrong microphone was chosen. Some decisions involving drastic processing — whether it’s equalization or compression — are often best left until the mixing stage, after all of the elements have been recorded.
Though the diagram at the top of this article puts the EQ at the end of the vocal chain, it can also be put between the preamp and the compressor [PROOFING NOTE: the given diagram does not include “Preamp” as one if its stages]. Its placement does make a difference, though; if placed before the compressor, any changes in the EQ of the track can cause the compressor to behave differently.
By choosing separate components (preamp, compressor, EQ) to make up the signal path, you can mix and match to get exactly the sound you want. Or you can combine two or more of the components in a channel strip. Quite a few manufacturers make preamps with EQ — the idea comes from the days of large-format consoles, when each channel on the console had a preamp, an EQ, and sometimes a compressor. These sorts of channel strips can simplify the setup (and minimize the number of rack spaces needed) considerably and sound at least as good as a vocal chain with separate components. A few manufacturers have all three components of a complete vocal chain built into one box. These units may be exactly what you need to create the right vocal chain.