Boston's Cathedral of the Holy Cross Relies on Symetrix

The Cathedral of the Holy Cross has dominated Boston's South End neighborhood since its construction just after the Civil War. With a seating capacity of 1,700 and a ceiling reaching to 80', the cathedral is the largest Roman Catholic church in New England and the mother church for the Archdiocese of Boston. In the spring of 2017, the cathedral embarked on its first major renovation, including new LED lighting and a large and complex sound system with Symetrix signal processors at its heart. Two years and $26 million later, the cathedral reopened for Palm Sunday services.

The new sound system offers a substantial number of inputs and outputs, which are transported over a Dante network to facilitate moving signals around the sizable building. Two Symetrix Radius NX DSPs handle all of these signals, with one unit dedicated to input processing and the other handling delays to the speakers placed throughout the cathedral.

System designer Evan Landry, president and CTO of Landry Audio, a division of CommLink Integration Corp, found the versatility of the Radius NX important in meeting the substantial needs of the cathedral system. "The Radius NX provides a great deal of flexibility in terms of processing, especially with the Super Matrix, which is processed on its own SHARC chip," Landry asserts. "We also have the ability to do logic inputs and outputs, which is handy for switching things on and off in the processing rack and essential for muting the audio system in the event of a fire alarm closure signal."

The system currently furnishes 32 channels of input, with the Radius NX offering British EQ and highpass filter modules on each input channel. Eight channels of wireless microphones are fielded by two Shure ULXD4Q quad-channel digital receivers. Another eight channels of wired microphones for the choir are routed to two PoE-compliant Attero Tech unDX4I Dante-enabled wall plates, each of which has four mic/line inputs with preamps and phantom power.

An Attero Tech unD4I-L Dante-networked interface receives the signal from the gooseneck mic that resides on the ambo (pulpit). The unD4I-L has four channels of mic/line inputs and four channels of logic I/O. The logic is put to use to sense a pressure mat at the ambo. The ambo mic gain is increased by 5dB in the Radius NX when the mat is stepped on and is removed when the speaker steps off the mat. This boosts the signal for speakers with soft voices, while avoiding feedback when no one is at the ambo.

Provision was made for four inputs from altar microphones, but these have not yet been needed. Similarly, a Symetrix xIO 4x4 Dante-enabled analog I/O expander is installed in the choir loft but is not yet in use as of this writing because the organ has yet to be reinstalled. Anticipating future expansion, Landry had 24-core multimode optical fiber run to the loft.

On the output side, the system feeds a custom-made Innovox MicroBeam 64 line array, plus 18 more Innovox line arrays along the support columns through the cathedral: 16 in the main nave area and one in each of the transepts. PowerSoft amplification drives all of the loudspeakers. Each of these units requires its own delay time in order to synchronize the whole system. Accommodating all of these delay times became the task of the second Radius NX, and the number of discrete outputs required was dealt with by installing four-channel analog output cards in the option slots of both Radius NX processors, as well as adding a Symetrix xOut 12 analog output expander.

Two controllers are used for mixing and control: a Microsoft Surface tablet running a user interface screen programmed by Landry in Symetrix SymView software, and a Symetrix T-5 touch screen controller. "Having a touch screen is really handy," Landry says. "It's programmable, so when someone changes their mind, as often happens with new projects, we can add a volume control, for instance, with just a program change. We don't have to put in another piece of hardware." Landry can even do changes or troubleshoot system problems remotely by logging in through a Nook PC in the processing rack.

The PA system is far from the only sophisticated technology at work. The cathedral's RF mic system is configured as three separate zones and employs two RF Venue Diversity Fin antennas and two Shure UA864 antennas, all of which are sent to an RF Venue 4 Zone antenna combiner. A fully equipped broadcast studio in the basement generates content for TV and webcasting and feeds the Catholic TV Network, based in Watertown, ten miles away. One of the Radius NX processors feeds signals through the Dante network, over a Luminex switch, to the studio's Yamaha QL1 console. From there, program audio is mixed and transmitted with video from the cathedral's broadcast facility, up an optical fiber placed on the building's spire, to a microwave transmitter that sends them to the John Hancock building near the city's Copley Square, from which the signals are then rebroadcast to Watertown.

The Cathedral of the Holy Cross project took nearly three years from the time Landry first asked to bid on the project until the work was finally finished. Success in such a large project depends on good relationships, something Landry had built with the archdiocese over time. "I had worked for the archdiocese a couple of times before we installed the system for them at Our Lady of Good Voyage in South Boston in 2017. That system also included a Symetrix Radius DSP and Attero Tech wall plates. The cathedral project started shortly after the Good Voyage project completed, so we were in a good working rhythm with them, and that made all the difference."