Power without Prominence
Nov 1, 1997 12:00 PM, Jack McLean
The wise blending of new components with current ones in developing a soundsystem can provide the customer with the advantages of improved performancewhile keeping an eye on the bottom line. Such was the case at the FirstEvangelical Free Church in Rockford, IL, where Joe Guarino of Audio- TrakSound Company recently completed the renovation of the house soundreinforcement system. Rather than scrapping the entire old system, whichwas installed at the facility's inception in the mid 1970s, Guarinocarefully selected components that could be retained while replacing thosenecessary to achieve the goals of the system renovation.
"In a system upgrade, I try to stay focused on the whole picture as itrelates to the customer, which extends beyond just the performance of thesystem to include budget and purpose-of-use considerations," he notes. "Astarting point is to prioritize. Look at what can be changed to provide thegreatest improvement, followed by continued evaluation of the system'scomponents and their performance, which may warrant further changes. But ifa component has been well maintained, works fine and will meet establishedrequirements, why replace it?"
Guarino also encourages the customer to provide input regarding componentselection. Doing so requires more time and effort in the form of productresearch, customer education, and often the need for demonstration.However, the result is a better informed client who is more confident inthe final decision, the contractor, and ultimately, the system.
Front-of-house loudspeakers are usually the first element of the systemthat Guarino evaluates. They tend to be the most sonically influential and"permanent" aspect of the system, often requiring the highest labor andcomponent cost as a percentage of the total system expenditure. For theFirst Evangelical project, he was given primary charge to design thesystem, evaluate the current component inventory, and recommend specificcomponents that would be required for purchase. He also consulted with DonLudwig of Ludwig Marketing, Kenosha, WI, for a secondary opinion ofspecific manufacturer products and a review of options.
"It is common for us to recommend larger capacity loudspeakers than acurrent situation might dictate," Guarino says. "In installations whereprogram needs can vary greatly, future requirements often demand expandedcapability from the loudspeakers, especially in respect to power handling.In terms of sonic performance as well as power handling, it is doubtfulthat First Evangelical Free Church will outgrow this speaker system. It isimpressive."
Prominent musicFirst Evangelical Free Church seats about 2,500 with in a parabolic-shapedsanctuary. A large balcony extends from the rear of the room, creating anunderbalcony seating area that leads to six overflow rooms immediatelybehind. Folding doors at the front of each room allow it to be opened tothe sanctuary when needed.
The ceiling is relatively flat, maintaining a height of approximately 40feet (12 m) from the main level. All floors are carpeted, except for thechoir area adjacent to the pulpit, and all seats have padded backs.
"Acoustically, the room's not too bad," Guarino says. "Originally, theupper balcony rear wall had been completely surfaced with acoustic panels,while the floor level had not. Subsequently, the church, in an attempt toreduce the differentiation in sound characteristics between these twoareas, installed a series of RPG diffusers. This had improved thesituation, but there remains a fair amount of slap off the back and sidewalls in the under balcony. A plan to treat these surfaces is currently inthe works." It is a plan that Guarino has highly and repeatedly encouraged.
Music has always played a prominent role in services at First Evangelicalwith full choir, orchestra, and electronic band featured. In addition,concerts by popular Christian artists hosted by the church have become morecommonplace, as have large-scale Christmas and Easter productions. It hadbecome apparent that a full-range system capable of producing the dynamicsand subtleties of the music programming would be needed to replace theoriginal central cluster system.
After supplying temporary full-range systems for a number of the church'sevents, Guarino had become familiar with both the membership and theirneeds and wishes for a new system. During this time, he had suppliedseveral A-B system comparisons, allowing key decision makers to betterunderstand sound as well as the performance of the system and specificequipment. When the decision was made to acquire a new system, he was askedto supply its design and installation.
Fully optimizedStereo capability to every seat in the sanctuary, to fully optimize musicprogramming, was added to the new system wish list. Yet the width of thesanctuary - more than 170 feet (51.4 m) - made fulfillment of this wish abit challenging. Guarino responded with a left/center/right (LCR)front-of-house loudspeaker design with arrays that would each cover theprimary seating area.
Left- and right-channel programming is fed via the two main outputs of thehouse console. Center channel programming, established on one of theconsole's matrices, is primarily comprised of vocal signals and providespoint-source localization, particularly enhancing the intelligibility ofthe spoken word.
The center loudspeaker cluster is arrayed to provide 180 degrees coverageto both upper and lower levels. Mounted as close to the ceiling as possibleto keep sight-lines clean, only about 1 foot (30 cm) down from the ceiling,the cluster consists of a top row of four Eastern Acoustic Works (EAW)MH690 mid/high loudspeakers in a tight-packed array that cover the balcony.Beneath that are four EAW BV150 bass loudspeakers followed by four moreMH690s tight-packed and covering the lower level.
EAW MH series are two-way loudspeakers specifically for large-scale,permanently installed sound reinforcement systems, and they are designed tobe used with the SB, BV and BH series to build precision arrays. Theyprovide exceptional control of horizontal coverage with tightly controlleddispersion in both planes, facilitating construction of arrays that provideboth high intelligibility and coherent music reproduction.
"The BV150s provide a very rich bass sound without being overwhelming,which is good for this cluster because it is used solely for voicereinforcement," said Guarino. "These loudspeakers also serve as a dividerbetween the upper and lower mid/high arrays, minimizing vertical signaloverlap."
The first five rows of seating are covered by two EAW UB82 compact,low-profile loudspeakers hung from the lower mid/high array, which havetheir own equalization and level settings, as do all upper and lowersections of each array. The pastor often walks through this zone wearing anopen lavalier microphone, so the goal was to achieve a bit more control ofthe loudspeaker system to enhance gain before feedback. These down-fillspeakers are adjusted to make a smooth and soft transition to the MHcoverage zone.
Left and right loudspeaker clusters, flown at the same height as the centercluster, include two levels. Each level has an EAW SB535 subwoofersandwiched between two MH690s. Positioned wide left and right, the clusterssupply 135 degrees of horizontal coverage in the mid/high-frequency rangewith their coverage overlapping to create the stereo image for virtuallyall seats.
At the outset of the project, Guarino inquired about covering theloudspeakers in some manner to make them less visible. The only requestfrom the client, however, was that they be painted to match the ceiling,which EAW was able to meet based upon a color sample. Very positiveresponse has been received regarding the design and appearance of the threeclusters.
As a relatively modern structure, the church offered plenty ofinfrastructure to support the loudspeaker clusters. But as an extra measureof precaution, Guarino consulted with the architect regarding supportissues and guidelines. Following this, he designed custom flybars --fabricated by Latham Industries of Rockford -- that span several beams andprovide ample support.
Informed choicesAll of the system's power amplifiers and most of the signal processors arelocated in the broadcast booth behind the house mix position at the centerof the balcony. These devices are mounted in a large double-bay MiddleAtlantic rack that was built into one of the walls to conserve space.Casters added to the bottom of the rack allow it to be rolled out forservicing. Conduit was already in place, simplifying cable runs from thecontrol room to the clusters.
In a proposal, Guarino presented a range of leading amplifier brands,evaluating them with specific criteria to the church staff. The choiceended up being three models from the AB International Pro series based on ahigh marks in sound quality and dependability. The lack of need forcomputer control and monitoring offered substantial cost reduction.
Pro series model 9620 amplifiers drive the bass loudspeakers. Model 9420units power the mid-frequency transducers and model 9220 units power thehigh-frequency devices. The center cluster is driven at 2 V; the left andright clusters are loaded at 4 V.
EAW MX300 processors supply crossover to the loudspeakers. A single stereoprocessor was used for the left and right clusters. The upper and lowerportions of the central cluster each have their own dedicated monoprocessor. Several equalizers supply individually tailored EQ settings forthe upper and lower portions of the system.
Again, through communication with the customer, a number of equalizersbrands were proposed before Rane GE60 1/3-octave graphic equalizers wereselected. Guarino points out that, in addition to good sound quality and anexcellent price point, he appreciated the GE60's continuously variableadjusting filters for precisely control of both the extreme high and lowends of the frequency spectrum.
The house mixing console, a 40-channel Yamaha PM-1800, had been added someyears earlier. Still in excellent condition and supplying the capabilitynecessary for this system, it has been retained. In addition, two1/3-octave equalizers from the prior system were also put to good use.Located adjacent to the console, they can be added to a channel orsubgroup, such as the choir subgroup or the pastor's microphone channel fora bit of extra tweaking.
Virtually all programming run through the system is live with only anoccasional tape or CD playback exception. A Sabine feedback exterminatorinserted in the choir subgroup allows a bit more headroom, particularlywhen the orchestra and band are in high gear. However, both it and theextra equalizer settings have been adjusted at the time of installation andcan't be accessed by system operators.
Routing schemes established on the console are simple and intuitive.Guarino points out that operators vary in experience, so the simplisticapproach usually works best. This philosophy was also the primary factor inthe decision not to add a lot of outboard effects processors; only a YamahaSPX-990 and SPX-90 were on hand.
"As an experienced live and studio engineer, I have come to expect a lot ofextra tools to patch into a system," he says. "But most of the operatorsrunning this system would not take advantage of them, so it would be moneynot well spent. Besides, this system sounds great as it is."
A mix of all subgroups, also with its own tailored equalization, is sent tosix EAW JF80 compact loudspeakers mounted from the ceiling at the front ofeach of the six overflow rooms behind the sanctuary. A single AB model 9620amplifier receiving a properly delayed signal drives all six, three perchannel. Offering a 90 degrees coverage pattern that covers the entireoverflow room, these loudspeakers primarily reinforce mid/high programmaterial that the clusters can't quite deliver given the obstructioncreated by the overhang of the balcony.
Positive imagingApthough starting to show its age, the stage monitoring system was alsoretained for the time being. An exception to this is the choir monitorsystem, which has been replaced by two EAW UB82 loudspeakers hung in aside-fill fashion. The units are controlled by a GE60 equalizer and poweredby an additional AB 9420 amplifier. The monitor amplifiers are locatedadjacent to the front-of-house system's power and processing racks in thecontrol booth. The floor monitor loudspeakers remain a combination ofvarious model wedges that can be placed as needed.
Guarino notes that the combination of the old and new has met with ravereviews from the client. "The most-heard comments have focused on theclarity and openness of sound quality as well as the positive impact of thestereo imaging," he concludes. "Our primary goal was to deliver very highquality stereo sound suitable for all the church's applications, and thishas been accomplished, much to their satisfaction."