The Salt Lake Tabernacle's One-Of-A-Kind Rigging
The one-of-a-kind Salt Lake Tabernacle, in Salt Lake City, is a venerable building to millions of followers of The Church of Jesus Christ of Latter-day Saints worldwide, and has been standing for nearly 140 years. Home to 11,623 organ pipes and America's most famous choir, the Tabernacle is celebrated for having nearly perfect acoustics.
Built when the only sound tech on America's frontier land was Mother Nature, the Mormon pioneers painstakingly constructed an all-wood, self-supporting, 150'-wide, dome-shaped roof with no beams or pillars to hinder views. Its elliptical design allows thousands of people to hear so clearly that it is common for tour guides to demonstrate the audio properties of the Tabernacle by dropping pins on the pulpit or tearing newspaper, which can be plainly heard throughout the building, up to 170' away.
For posterity's sake, the Tabernacle was closed to the public for two years for major seismic renovations and general upgrades. Enter Stage Technologies, a UK-headquartered automation mechanics and control systems firm.
“We worked with The Church of Jesus Christ of Latter-day Saints in 1999 to install a 40-axis automation system at their conference center in Salt Lake City and again in 2001 to supply a portable system for their modular lifts. Their Tabernacle building is just across the street from the conference center,” explains Stage Technologies CEO Kevin Taylor.
Stage Technologies' main responsibility on the renovation was supplying and overseeing the installation of the entire rigging system along the Tabernacle's delicate attic, and they worked with Bronx, NY-based installation contractors Pook Diemont & Ohl Inc. and lighting truss manufacturers Tomcat USA. McLaren Engineering Group, of West Nyack, NY, provided design services for the rigging systems. AMC Fabrication of Henderson, NV, designed and fabricated all the rigging blocks and designed several custom, field-adjustable rigging blocks that could tilt, swivel, and rotate, in both singles and multiples. In total, there were about 200 rigging blocks onsite, with at least 12 variations.
The structure's interesting setup and delicate construction called for large-capacity winches and associated rigging to carry lighting trusses with focus baskets, speaker clusters, chandeliers, and harnesses for personnel who clean the pipe organ. The project also called for installing two tension-wire grids. Custom sheave blocks were developed to route wire ropes and electric cables to the suspended elements.
“There are lighting trusses, chandeliers, and speakers overhead in the Tabernacle,” explains Bill Gorlin, a VP with McLaren Engineering Group and chief of the firm's Entertainment Engineering division, who worked as project manager on the renovation. “We did the trusses for Tomcat, and we also worked on junction boxes for the chandelier contractor, Cache Valley Electric of Salt Lake City. All the equipment hanging over the audience is rigged to cable that eventually makes its way over to big electric winches that allow them to move up and down. Head blocks, loft blocks, and mule blocks were used for electric cable management. They had a lot of custom cables.”
Carrie Robertson of Tomcat describes the custom trusses. “We created 21 sections of custom truss 26" tall and 36" wide; 18 of them were 15' long,” she says. “One was 123" long, and two were 128" long. They have a lamp bar chord running under the truss, a cable channel built into the bottom, and an I-beam installed for the focus chair to travel on. All of the trusses were powder-coated ETC white to match the lighting fixtures. There were also 18 custom pick-up bars designed to work with the truss.”
The chandeliers were completely rehabbed and updated, says Gorlin, and then attached to winches so a button could be pressed allowing the chandelier to come down and be serviced — same thing with the speakers and lighting trusses. “You press a button, and they come down, and you change whatever you want and send them back up again. You can change out lamps and lighting units, and you can move them around and get them properly focused using a focus basket for one person with fall protection. When they fly the truss back out, the person stands in the basket, and they can manually pull themselves along the length of the truss and focus all the lights because you can't focus the lights when they are down low; they have to be up high. And once the lights are all focused, you bring the truss back down, and the guy gets off, and they fly the truss back up again to the proper height.”
While the renovations were part of a larger earthquake-proofing of the Tabernacle, the main goal of this project was to make the systems safer while also making it easier for staff to maintain and repair chandeliers and lighting in the 3,500-seat building, along with a complete upgrade of the lighting and sound systems, making it a world-class performance space. Yet each improvement presented its own unique set of challenges.
“The attic presented significant challenges for routing the cables since each cable that drops vertically had to run over a series of sheave blocks forming straight-line facets between the curved plaster ceiling and the curved attic,” says Gorlin. “All of this had to be done while missing large wooden framing members.” Welding was not allowed inside the wooden structure, Gorlin notes. “This meant the installation included many custom, field-clamped and field-drilled mounting applications. If this had been any other venue, we would have liked to field weld them, but we couldn't, so it was a really challenging detail for installation.”
Stage Technologies' Taylor agrees. “It was a real challenge installing the winches, as there was very limited space in which to maneuver,” he says. “It was also a very large job, producing a means to divert all-steel wire rope past a huge amount of obstructions throughout the venue.” To install all of the rigging, the cables had to go up and come down around a curve, and then drop back down and go up again. To change direction, sheave blocks were used for every single cable, coordinated through the maze of existing wood and equipment, with attachments made from field-drilled clamps.
Steve Sywak, a senior mechanical engineer with McLaren, also worked on the project and observes there are some extremely notable features on the Stage Technologies winches. “The main feature is that when the winches wind and unwind, the drum, gearbox, and motor shift so that the cables don't have to, so the line stays straight, and the cables are more reliable with a much longer life. Also, the winches have electronic circuits built into them to sense how much force is on the line so they don't apply too much force if there's a problem — I hate to say it — down the line. They can sense if the force gets too high or too low, and they can shut themselves down and have someone go check on them.”
Turning on the cyc lights in the Tabernacle has a much brighter effect now, with 468' of Selador X7 color LEDs provided by Selador and installed by in-house personnel. “The seven colors were definitely the reason we chose them,” says staff A/V specialist Lorin Morse. “But they can be very difficult to focus smoothly. Our cyc wall moves in several different directions since it is the dome wall, and the cyc units aren't mounted uniformly.”
As for the sound design, completed by Kirkegaard Associates, Salt Lake Tabernacle's senior audio engineer Trent Walker explains the unique design and challenges the room presented acoustically: “The sound rigging is tied in with the lighting rigging. Kirkegaard did a great job keeping the system as low profile as possible, as the key to the room is that it is a very live space, and the reinforcement system needs to be as natural-sounding as possible.” The main challenge in installing the system, Walker notes, is that the historical building's unique acoustical characteristics needed to be preserved.
The Salt Lake Tabernacle officially reopened again at the end of March.
For additional Live Design coverage of this project, including the involvement of Auerbach Pollock Friedlander, Performing Arts/Media Facilities Planning and Design, please see the online article Auerbach Pollock Friedlander Completes Work At The Historic Salt Lake Tabernacle
14 BigTow390 Winch
7 BigTow290 Winch
3 BigTow200 Winch
Control for stage and thrust elevators
1 Nomad Control Console
1 Solo Radio Handheld Controller
4 Motor Control Cabinet
1 Motion Control Rack
8 Vari-Lite VL3000Q
48 High End Systems Color Command
468' Selador X7 LEDs (2', 4', and 6' lengths)
120 Ocean Optics SeaChanger
5 ETC Sensor+ 48 dimming
2 ETC Sensor+ Sine Wave dimming (house lights)
18 ETC Source Four PAR
145 ETC Source Four 5° and 10°
14 City Theatrical AutoYoke®
4 ARRI 5kW Fresnel
8 Wybron Nexera
3 ETC Eos console (one in the rack for backup)
1 ETC Emphasis console
20 JBL VerTec Line Array
10 Renkus-Heinz Speaker
6 Duran Intellivox Line Array
L-Acoustics 108 and 112 Monitor
Dolby Lake Contour Processing
Crown IT and CT Series Amplifier
MediaMatrix DSP
Yamaha PM5D FOH Console
Euphonix System 5 Recording Console
Digidesign Pro Tools HD3
Wilson Audio Monitors 5.1 mixing
Schoeps, Beyerdynamic, Peluso, DPA Microphone