There are very few rights and wrongs regarding the sound of a live audio mix, and while there are multiple ways of arriving at a final result, the ultimate criteria for assessing said mix should be that it sounds and feels good in the space one is trying to fill. Of course, this is a challenge thate seems to be right out of the Idiot’s Guide to the Sound Universe — a real “Duh” moment — but we all know this task is easier said than done.
Advancements in technology have provided us with more comprehensive tools at fingertip’s control with which to work. Although newer amplifiers, speaker arrays and delays have enabled us to get more clarity and coverage in any given space, there is still the issue of psychoacoustics and subjectivity. What sounds good to one person does not necessarily sound good to everyone else.
To be clear, not every mix should — or can — sound the same. We are all aware that an EDM concert should not be mixed in the same way as a symphony orchestra, and vice-versa. As long as the proper tools are provided for the space, then the sonic quality of the show becomes the responsibility of the engineer hired to mix the event. How they achieve a “good” mix depends upon how that engineer conceptualizes the music at hand, how well they hear and their ability to manipulate the given technology.
Inboard/Outboard
Most engineers have an arsenal of tools they use on a regular basis to create their sound and, as engineers, we become reliant upon these particular pieces. Fortunately, DSP technology has supplied a means to have hundreds of (virtual) outboard units on any given mix and — unlike analog mixing — the necessity to choose which track should receive the assist from an outboard processor has turned into choosing which plug-in not to apply.
Most outboard devices were created for and used in major recording studios before they found their way onto the riders of touring bands. The recording engineers — when in need of recreating their recorded sounds in live mix situations — would take studio pieces such as their Lexicon 224 reverbs as well as the Manley and LA2a compressors. While these units became a touring standard, they were not made for months of bouncing around in a truck and were cost prohibitive for most touring acts except those at the very top. More affordable and durable pieces were manufactured with the touring and live market in mind, and these units then became standard rider requests.
I am never one to question an engineer’s request for gear. How one mixes and what they feel they need to make their show a success are as subjective as denoting what sounds good. I understand why such plug-ins as the Waves C4 and C6 multiband compressors, MaxxBass, Vocal Rider and Renaissance verbs have become popular. I don’t quite get the Aphex Aural Exciter plug-in, but then again, I never got the analog piece either, although engineers I’ve worked with swore by it as a must-have item. Maybe my ear isn’t refined enough to hear what it does, but my lack of sensitivity brings me to another piece of equipment that is a regular rider request, but one that I question as necessary in certain live situations — the word clock.
The Word Clock Issue
The word clock debate is almost as contentious as the last presidential debate, but with an even more subjective outcome. Practically every digital device has an internal word clock for ensuring that the timing of the sampling rate is kept to precise and regular intervals. (See related Theory & Practice column, this issue, page 49).
In a studio situation with multiple digital devices, a master clock is an absolute necessity. Slaving the various pieces of equipment from the master word clock will then guarantee that there will be no “jitter” or drift between them and that all the generated data from the different devices will arrive at the same time and rate. I visualize this as digital phasing, much like a speaker system that works best when all the speakers are moving in the same direction at the same time. A word clock is also imperative in A/D conversion, such as with the preamps in a mixing console, but given that every digital console has an internal clock, the question remains as to whether or not the sound quality is improved by using an external clock; especially if it’s only in conjunction with the console and no other digital interface.
I work with engineers who use an external word clock with every console ranging from the Yamaha LS9 to the DiGiCo SD10, and they contend that the sound is enhanced when overriding the internal clock with an external clock. Considering that my argument being the internal clock should be sufficient on any given console, I set up a little test. The first console I tested was the Avid SC48. Using an SM58 into channel one on the console with a QSC K12 speaker plugged into an aux, I spoke into the microphone while switching between the Antelope OCX word clock and the SC48’s internal word clock. To my ear, there was no discernable difference, but when we did the same test in the same way with a Yamaha LS9 16-channel console, there was a distinct change. In no way was this a definitive test, and I cannot claim that the perceived audio from LS9 with an external clock is better than the audio from its internal clock, but I can say that there was a distinct change.
Since I carried out my meager test, I have spoken to a few different users who agree with my belief that with most new consoles, the external word clock is not a necessary addition in terms of sound quality. Of course there are those that disagree and will not be dissuaded from using an external clock regardless of the console.
Outside Opinions
Realizing that I should consult a higher power, I called upon the great Google and found that my assumptions were not without merit. I found a rather in-depth article written by Hugh Robjohns regarding the subject and, after running multiple tests, his conclusion was that, in older consoles, the internal clocks were not always the best, but that today’s converters often work best with their internal clocks. Dave Rat also blogged about this subject and, with an oscilloscope, compared the square waves of an M7CL with a Big Ben attached and those emitted using its internal clock. There was a definite difference between the two as read by the oscilloscope, with the internal clock being the anomaly. Despite the visual unattractiveness of the signal, they were not able to conclusively prove that the audio itself was changed for the worse. Even though there are irregularities shown in the older Yamaha consoles, I still contend that, for a simple setup — which does not employ multiple devices — an external clock is unnecessary in regard to improving the audio quality of the signal or mix.
While I’m sure to be challenged on this matter, I should say that regardless of my own assertions, I would never tell another engineer what tools they do or do not need to make for a great mix. In any case, the best decisions come from your own ears.
