The topic of headphones for live engineers discussed in this column last month has generated a more detailed thought process in which I began to chronicle the various tasks accomplished each day at FOH using a set of headphones. It seems somehow ironic that at each show, I perform my work on a huge arena or stadium line array sound system, but I still spend much of my time behind the console inside the private world of my headphones. I then expanded those thoughts by touching on other current tools used for particular tasks that often come up daily.
A Typical Tour Workday
During a typical tour workday, rigging call is 8 a.m. Sound call is usually an hour later when the full complement of local loaders and stagehands come on the clock. I make myself available for consultation with the systems engineer and the tour rigger when deviations from the rigging template are required. The systems engineer and I will then go over the complete game plan for that day’s P.A. deployment. Wherever accurate physical data has been collected, we employ Clair Global’s excellent prediction software for the Cohesion-12 system. Clair’s library of structural information for North American venues is vast. It contains a wealth of precise, building-specific points of data used to create an accurate model of the performance space. This information is crunched by the prediction software to calculate the multiple specifications that will optimize the line array system’s fidelity, volume and distribution.
When sound gear starts rolling into the building, I move out to the FOH position. The promoter rep, our stage manager and I determine the day’s specific location for our control area. I work on a 12-by-10-foot space the floor. The 16-by-12-by-1-foot lighting riser starts just behind me. And the two 8-by-4-by-4-foot video risers are right behind lighting position. I try to get this business done before too much gear is delivered to FOH so no one is cramped or encumbered by heavy road cases. I customarily work with the building personnel to get the various risers pulled, built and placed. When this construction is completed and lighting, sound and video cases are sorted and positioned, I can start building my own world at FOH and running the audio snake(s) back to the stage left area.
AC power will not be up at FOH for a couple of hours, so one must turn to other tasks. In the audio department hierarchy of work projects, the job of rigging the stage left sound points is of primary importance. Each chain motor must be hung and certified by the riggers before the stage left P.A. can be assembled and flown into place. Only when the stage left P.A. columns and lighting instruments are completely cleared of the floor can monitor world and patch world be safely built and the snake runs from FOH connected to power and the stage racks. However, there are always valuable things that can be done before I hear that friendly beep from the UPS and its display dimly lights up in my FOH electronics rack.
Quite often, the first tool that comes out of the FOH workbox in the morning is the Nikon Forestry Pro range finder that Clair Global provides with the their system. It has become an indispensible piece of digital gear. This handheld unit provides extremely accurate three-point measurement for linear distance, height and actual distance (hypotenuse) between two points. It is extremely useful during the load-in process for verifying seating area heights, chain motor hook heights, or double-checking my console’s distance from the stage.
Observing and Adjusting
We often use this time to make additional observations about physical characteristics of the building that may affect the distribution of sound in the audience area. What we see and notate may cause us to alter parts of the information provided to the prediction program. We may respond by modifying angles between cabinets in the line array column or adjusting the overall heights of each array. If changes to the data previously entered into the prediction program are required, this is when that job should done. The systems engineer and I confer and then relay any changes to the crew constructing stage left in a timely fashion.
Other observations are more empirical in nature. Temperature affects the speed of sound. The nominal velocity of 1,120 feet/second at sea level increases with temperature. Relative humidity affects the attenuation of sound. Water vapor weighs less than air, therefore moist air is less dense than dry air. Drier air absorbs far more acoustical energy than moister air, especially above 2kHz. It’s always a good idea to carry a thermometer/hygrometer combination device such as the one pictured above (center) by ThermPro to monitor changes in prevailing atmospheric conditions. Shows are usually performed in temperature and humidity controlled environments, but large enthusiastic crowds may affect both parameters. Of course, there are the great stories about the old Sportatorium in Hollywood, FL having its own weather — with clouds forming and rain falling inside the venue due to the extreme amounts of heat and water vapor emitted by a sell-out crowd. (I know I have a few.)
Later in the day, when the power does come on at FOH, I will use the range finder to determine the distance between my head and the cabinets in the forward facing line arrays that are most closely aimed at me. This Nikon device reads well on dark objects, and the readout gives me the starting point for calculating the delay time I will need on the headphone buss to match the arrival time of sound from the P.A. system. As I said last month, correctly setting this delay immeasurably cleans up what you can hear in the cans when the main audio system is operating at show level. It’s easy enough then to bypass it for real time tasks like effects settings.
The observation period ends when the stage left P.A. is flying and parked at its predetermined heights. At that point I work with the sound techs to finalize height, tilt/pullback and horizontal aim of the various columns. When stage left is nailed down, I then head over to stage right to run chain motors and help in the array assembly process that was just completed on stage left. It is always to my advantage to participate in this process of assembly, because the faster stage right flies, the more time I will have to work with the complete system before line check and sound check.
Once stage right P.A. is in the air, aimed and leveled, I then head back to FOH to power up everything in my world. The first order of business is to reload my current show file on the DiGiCo SD5 console and verify the system. With the mixing desk plus the Pro Tools computer system up and running, I am able to visibly check through all the connections to devices within the console’s network — the stage racks, the Optocore network, the MADI connections and the Waves SoundGrid system.
The Most Important Tool: Headphones
For the next 30 minutes or so, the ground subs are being deployed, the frontfills are getting laid out and amp racks are being connected. That becomes my window to accomplish mixing specific tasks. This is when my headphones once again become the most important tool in the FOH workbox. I need to prioritize tasks in this limited time window before the console becomes devoted to noising the full audio system.
While I don’t recommend mixing a show on headphones, I do rely on the information I hear on the cue buss throughout the day. Next to my ears, my headphones are the most important tool I bring to the workplace.
Here’s a list of a few circumstances for which headphones are the best critical listening medium while I am simultaneously occupying a busy, noisy, public environment.
• Isolating, identifying and describing extraneous noises
• Auditioning effects and/or plugins using virtual sound check tracks or test mic
• Time alignment of separate sources derived from a single instrument
• Comparing characteristics of multiple transducers used on a single source
• Polarity testing of stereo or summed mono sources
• Verifying quality and troubleshooting tracks recorded on DAW
• Rehearsing specific fader moves using multitrack playback
• Paying attention to the stage by listening to the star mic
• Pre line check source verification and discovering possible problems
Checking Signal Quality
When troubleshooting requires listening to signal presence and quality between Point A and Point B, a portable headphone cue box becomes a necessary implement. Clair Global provides an excellent audio line-testing tool that has now replaced the venerable Q-Box in the FOH workbox. The dBbox 2 from CTP Systems in the U.K., with its multiple input and output formats from AES/EBU to hi-z analog, has become a 21st century audio Swiss Army Knife. It handles a wide variety of input and output tasks with incredible agility and has become an essential verification and troubleshooting tool for all digital console setups. The specifications can be viewed at www.
ctpsystems.co.uk/dbbox2.html.
Carefully chosen headphones allow me to experience a private, predictable and polite listening environment. I believe headphones, as opposed to speakers, should always be used in any shared public space. I try to give my fellow FOH-dwellers as much peace and quiet as I can despite my job description. I choose not to use a “shout” speaker, nor do I set up the nearfield monitors on a daily basis. We have, however, carried a pair of Tannoy 12” or 10” coaxial monitors for many years. These are always available on the loading dock when specific gig conditions dictate their use. But I believe I am responsible for generating more than enough inconvenient noise when the big P.A. is kept on for extended periods of time while I am tuning the complete system or performing line check. A little consideration costs me nothing.
When sound check begins, the delay on the cue buss gets punched in and the headphones become relegated to their more ancillary but still completely necessary status.
Safe Travels!
