Corporate Audio SoundCORPORATE AUDIO DEMANDS HIGH-END SOUND 1/01/2012 4:00 AM Eastern
Sound reinforcement for events in hotels and convention centers has been a huge industry for many years. It goes through cyclical up and downs, like most corporate-related services, but right now it’s only getting bigger and more production-oriented. Ballroom events, meeting rooms, multipurpose venues, video conferencing, telepresence—they’re all proving a fertile ground for today’s audio school graduate. Often, professional A/V companies are the first employer for many of the students graduating today. Mix asked Chris Thomson, a 2002 graduate of Ex’Pression College for Digital Arts and now a technical coordinator at Swank Audio Visuals in San Francisco, to let us know what a typical day in the life of a first job might look like.
Corporate, medical and political events are becoming ever more complex as meeting planners expect the speakers presenting onstage to sound clear while integrating seamlessly with video, lighting and staging. In fact, the corporate-event sound engineer’s skill set includes many of the fundamentals that concert sound mixers adhere to, and the consoles, loudspeakers and processing gear is increasingly of the same type and quality. While the majority of the job involves dealing with the low sound pressure level of the speaking voice, it’s not uncommon to find an A1 working a press conference in the morning and then mixing Carlos Santana for a Silicon Valley product launch in the afternoon. An event I recently engineered for commercial real-estate company CoStar required using all of the fundamental corporate audio skills, including proper speaker positioning, effective lavalier microphone placement, voice-specific EQ techniques, correct wireless RF programming, podium microphone compression and, finally, proper gain structure.
CoStar’s event was held in the ballroom of the Westin Market Street hotel in downtown San Francisco. The ballroom is an elegant 9,040-square-foot rectangular space measuring 114x80 feet. The setup day began at 7 a.m. I joined four of my Swank Audio Visuals co-workers to begin the gear push from our various storerooms located throughout the hotel. By 8 we were ready to begin the event setup, which called for three 17-foot, fast-fold, rear-projection screens, 60 feet of pipe and drape, two lighting trees and the sound system.
The sound equipment included four Meyer Sound UPJ loudspeakers for the mains, two Meyer UPMs for the front-fills, a 32-channel Midas Venice console, and an audio rack with the processing gear and wireless mic units. A crew from CoStar’s IT department was providing (and setting up) the projectors and video-switching equipment. They were scheduled to arrive at 2 p.m. My team planned to be finished with the hard set so that the projection work could begin once they arrived. As three Swank workers assembled the lighting trees and projection screens, I teamed up with my audio assistant, Brandon, for the sound system setup.
First, I needed to examine the room’s stage, seating and tech riser positioning, already set by the house according to the client-approved CAD diagram. The two things that stood out to me were the position of the tech table and how some audience sightline issues would dictate my speaker placement. The tech table was positioned on the stage-right wall. It is best to mix from the back of the room near the center, but in the corporate A/V world, side-wall tech tables are common. I positioned my 32-channel Midas on the end of the table furthest away from my planned speaker position so that I could hear a more on-axis sound. As Brandon rolled over the speaker cases and Ultimate speaker stands, I began plotting the best locations.
This particular show called for the audience tables to be set fairly wide and not too far back from the large stage (32 feet wide). Also, the two outside 17-foot-wide projection screens forced me to place the speakers further from the stage than usual. No truss today, so with this floor-based speaker set, I chose to cluster two speakers outside the screens instead of splitting them due to sightline issues.
To accommodate the video tech table, we had to set the speakers about two feet behind the front of the stage. It is almost always good practice to place the speakers in line with, or in front of the stage’s front edge, but that was not possible for this show. Also, the wide set of the room tables in relation to the stage did not allow for delay speakers to make a difference. The two Meyer UPM front-fills placed on the stage were going to help, but for the most part sound would be coming from the two UPJ clusters set wide, seven feet high, angled toward the stage more than usual, requiring that sound be pushed 70-plus feet to the back center of the room—not ideal, with potential for greater-than-usual feedback problems.
MICS AND EQ
The microphone used for this corporate event (and most A/V events in general) was a wireless lavalier: a Shure UR4S. The obvious advantage of a wireless lav over a podium mic is mobility; the disadvantage is poor gain-before-feedback. The small-cap condenser element on these UR4S mics has the same cardioid pattern element used in my favorite podium mic, the Shure mx418. The crucial difference is where the mics face the mouth.
Two problems with a lav on clothing are low-end chest resonance and chin blockage. Placing the lav mic element about seven inches below the person’s head is good practice. If it is too far down, the mic doesn’t pick up as much of the voice, causing more feedback issues. If pinned too high, the mic picks up even less high end. Generally, the console preamp has to be pushed harder, and the high end (8 to 20 kHz) needs to be boosted. The extra gain will require more EQ adjustments.
The equalization techniques required for a corporate event are quite different than the techniques used doing sound for a band. A presenter at a corporate event is just talking and sometimes a timid person will speak at a very low volume. This, compounded with the feedback-generating position of lav mics, requires a careful “ringing out of the room.” It is often taught at audio schools that only four to five feedback frequencies should be moderately notched out of your 31-band or parametric EQ. This is a rule that I strongly believe in but rarely see followed by beginner sound engineers. Pulling too many frequencies (ones that are not actually feeding back) will just bring down the room’s overall sound level and lead to descriptions like muddy, tin-like, fake, thin, etc.
Although the compromised speaker placement at the CoStar event posed a feedback problem, I was able to get plenty of gain using careful and spare EQ adjustments. During the day, Brandon acted as a test speaker onstage. Soon I had rung out the feedback frequencies on my rack’s 31-band EQs. Next, I worked on the mic input channel strips of the Midas Venice. Boosting the strip’s 12kHz knob brought my assistant’s voice “to life” with the high-end “air” that is the part of the human voice. Often there are multiple mics on at once, and the variety of presenters will need different adjustments. A good sound person should be able to dial in EQ adjustments within seconds of a speaker talking.
Wireless microphone programming can be problematic in today’s RF-bombarded airspace. In general, most wireless mic transmitters will not send signal through more than two walls, so it is doubtful a mic kit being used in a hotel across the street is going to cause you any trouble. But all kits being used in your building should be set on different frequencies and monitored closely. Most mic manufacturers have preset groups of frequencies that do not interfere with each other, but sometimes you are forced to use multiple group settings because of a lack of open RF channels on one group. In this case, you should turn on all the mics and test them to uncover any intermodulation problems. RF problems can be greatly reduced with proper preparation; however, it is a good idea to have a wired mic or extra wireless handheld available onstage in case hits occur.
Compressor technology comes in handy when amplifying the speaking voice. A person speaking into a podium mic should be standing with their head about a foot away. In reality, this is sometimes not the case. If they are too far back, a well-rung-out system will still pick up the person’s voice. If they do the opposite and get their mouths too close, the microphone can be overloaded and create loud, boomy “plosive” sounds. Cutting some of the low end on the channel strip will help, but the main tool to fight this problem is a compressor. Compressors have many uses when mixing a live band, but this is the main use when amplifying sound in the corporate setting.
As I mentioned before, a lavalier mic input should be set to pick up strong level (good signal-to-noise ratio) without clipping (proper headroom). This method of setting a strong level should continue down the signal flow chain, through your preamp, EQ processing gear and all the way out to your speakers. Having a preamp set low will cause problems as boosting a weak signal down the chain can raise the noise floor. Another problem with a weak preamp level is you may not be able to see the channel’s LEDs light up. These lights come in very handy when a group of people is onstage and you are riding the faders. Adding mics onstage will increasingly reduce the gain you have available. Every time you double the number of mics, you lose 3 dB of gain-before-feedback. For example, two open mics will lower your volume 3 dB and eight mics will lower it 9 dB. This is quite a bit of volume loss; even the best sound person will be riding faders in this situation.
Sound engineers working in a corporate setting will face difficult situations. Meeting planners expect excellent results regardless of the room’s shape, stage positioning, table setup and screen locations. And in many ways, with just a voice out front, clean audio is even more crucial. If you have a room of 40 venture capitalists and they are talking big deals, every word counts.
Think back to what you learned in school, then apply it in the real world. The basics do matter: proper speaker positioning, effective lavalier microphone placement, human voice specific EQ techniques, correct wireless RF programming, podium microphone compression and correct gain structure. Understanding these issues is necessary for success in the world of corporate sound.