Article

Tuesday, March 09, 2010

Church Sound Basics: “1,000 Watts” Isn’t Necessarily 1,000 Watts By Some Standards

Avoiding the error of purchasing and using an inadequate amplifier based on misleading wattage claims

At some point in the past, certain power amplifier manufacturers got hip to the fact that the only specification most power amp buyers pay attention to is wattage. 

Sadly, they decided that misleading specs were OK as long as it created better sales. Hmm….

For purposes of our discussion, let’s consider two amplifiers. Amplifier A is rated at 1,000 watts (per side), into a 2-ohm load, with .1 percent Total Harmonic Distortion (THD), measured at 1 kHz, while Amplifier B is rated at 1,000 watts (per side), into a 4-ohm load, with .03 percent THD, measured full range from 20 Hz to 20 kHz.

Let’s break this down, starting with load. All amplifiers, regardless of manufacturer, will provide more power into a 4-ohm load than into an 8-ohm load. Less resistance from the loudspeaker(s) will allow more output from the amp. 

Similarly, the amp (if it will run at 2 ohms; some would rather not) will provide more power into a 2-ohm load than a 4-ohm load for the same reason: less resistance. 

Let’s imagine you have four 8-ohm loudspeakers all running off of one channel of Amplifier A (which results in a 2-ohm load at the amp output, and most professionals won’t do this).  Each loudspeaker is provided with 250 watts.

Now let’s look at Amplifier B. It delivers 1,000 watts into a 4-ohm load (the equivalent of two 8-ohm loudspeakers), so each loudspeaker is provided with 500 watts. An amp that will provide 1,000 watts into 4 ohms will typically provide about 1,600 watts into 2 ohms.

Therefore, each loudspeaker in the 2-ohm scenario is provided with 400 watts rather than the 250 watts cited in the previous example. 

The moral of the watts story? “1,000 watts” isn’t necessarily 1,000 watts by some standards.

The breakdown continues: Amplifier A was measured at 1 kHz, while Amplifier B was measured full range, 20 Hz to 20 kHz.  Full range (also called full spectrum) audio requires exponentially more power than a single frequency. 

Liken it to a couple of Olympic shot-putters. They can both put the shot 30 feet, but the first guy uses a shot that weighs 4 pounds,while the second guy uses a shot that weights 20 pounds. Which guy is stronger?

In our case, the amp (Amplifier B) that puts out 1,000 watts from 20 Hz to 20 kHz is substantially more powerful. 

The moral of spectrum versus output measurement? “1,000 watts” isn’t necessarily 1,000 watts by some standards.

The breakdown continues further: Amplifier A showed us 1,000 watts at .1 percent THD, and Amplifier B showed us 1,000 watts at .03 percent THD. I did lousy in math class, but even I know that .03 percent distortion is a dramatically lower figure than .1 percent. 

The moral of the distortion measurement?  “1,000 watts” isn’t necessarily 1,000 watts by some standards.

There are other power amplifier specs that are interesting, but they deal more with efficiency, speed and other “esoteric” considerations.  Here we’re simply looking at the nuts and bolts of understanding basic amp ratings.
 
It’s entirely possible that Amplifier A will work just fine for your application. It is, however, also entirely possible that Amplifier B, usually (but not absolutely always) at a higher cost, is the right choice in order to get the safe clean performance that your application demands - now and far into the future.

With that in mind, if you’re looking at an amp that’s quite inexpensive for the amount of power it will allegedly provide, definitely ask to see the specs.

And now for a new moral: Don’t make the error of purchasing and using an inadequate amplifier based on misleading wattage claims. Inadequate power can result in lack of clarity and enunciation in your system and can even blow your loudspeakers if there is too much demand placed on the amp.

Jon Baumgartner is a veteran system designer for Sound Solutions in Eastern Iowa, a pro audio engineering/contracting division of West Music Company. Feel free to e-mail him with your questions at .(JavaScript must be enabled to view this email address).

More Church Sound Basics articles by Jon Baumgartner on PSW:
Graphic Equalization Can Make A World Of Difference
Using Compression To Benefit Overall Sound Quality
Locating Your Loudspeakers & Related Issues
Proper Console Gain Structure, Maximizing Signal-To-Noise Ratio

{extended}

St. Mary’s Simplifies Audio Workflow With Symetrix Automix Matrix 780

The Automix Matrix has alleviated staffing issues and allowed the Father to control his volume with confidence.

St. Mary’s Catholic Church in Albany, Oregon had several audio issues they needed to resolve.

While some were structural like the unforgiving reverberant space and improper loudspeaker placement, others were functional such as being forced to use an entire mixing console for minimal audio needs.

The church hired Portland-based contractor Delta AV to help solve their multitue of audio dillemas.

“From our initial discussions, it was apparent that 85-percent of their services required just one mic at the pulpit and one wireless mic on the pastor,” recalled Delta AV system engineers, Steve Jellerson and Kurt Bevers, who led the project.

“They were having scheduling issues trying to get someone in to run that minimal sound system, and the whole situation seemed unnecessary to us.”

Bevers designed the new system around the Symetrix Automix Matrix 780. Four wireless mics, a pulpit mic, two floor jacks (intended for choir mics), and output from a video switcher, feed the 780.

Located right at the pulpit for easy access for the pastor, an AMX interface provides access to mute/unmute and volume for each input. A Yamaha LS9-16 digital console mixes the worship band, which consists of drums, acoustic guitar, bass, keyboards, and six vocalists.

“We’ve found that in a lot of churches, it’s to everyone’s advantage to keep the spoken word and music mixing separate,” said Bevers. “That way, it’s impossible for the music mixer to interfere with the pastor’s reinforcement, which is, of course, paramount in the Catholic Church.”

Bevers continued, “We’ve also found that the key to a successful system depends just as much on the interface as it does on the technology itself. The biggest obstacle to success is people’s pain threshold. If they think using the system is going to be painful, they simply won’t use it. If it takes more than three or four lines to describe a procedure, the procedure is wrong.”

“The Symetrix Automix Matrix 780 allows me to have tremendous processing power under the hood, but to present that in a wonderfully simple way to the user. Although it is technically a fixed-configuration processor, the flexibility inherent in the 780 goes a long way toward solving almost all of the mixing problems I’ve come across.”

“St. Mary’s is in love with the new system,” reported Bevers. “The control issues have vanished, making everyone’s life simpler and more harmonious. The Father controls his own volume with confidence. The improvements to the coverage patterns are also remarkable.”

“Now the Father can put a headset mic on and walk anywhere in the sanctuary. Not only is he heard, he doesn’t have to worry about feedback! It’s quite literally a revelation for them. They had never conceived of being able to attain that level of interaction and engagement.”

Symetrix Website

{extended}

OmniLine Array Transforms Audio In Landmark Episcopal Church

Martin Audio Arrays chosen for their intelligibility in a challenging space.

St. David’s Episcopal Church, in Philadelphia is a church with a very distinguished history.

First settled at end of 17th Century by Welsh, the church will celebrate its 300th Anniversary in 2015.

Now the largest of 157 parishes in the Diocese of Pennsylvania, St. David’s needs have changed greatly since its founding

The chapel’s original audio system was intended to amplify sermons and choral voices in a large, reverberant space dominated by an impressive 3-manual, 47-rank custom Dobson Organ.

Consisting of 32 speakers mounted around the upper tier of the long rectangular worship area, the system had one major flaw.

It was incapable of producing coherent intelligible vocals throughout the sanctuary.

Said John Schofield, Parish Administrator, “When the chapel opened, the announcing system was impossible.”

“You couldn’t hear a word anyone was saying or understand it, for that matter.”

The church sought the services of design/installation firm Spinnaker Multimedia Solutions.

Fenicia Redman, VP Project Development elaborated on the project, stating, “St. David’s wasn’t happy with their audio so we performed an acoustic study and 3D modeled the room using EASE acoustic prediction software. “

“It came down to two brands, one of which was the new Martin Audio OmniLine array, and we installed each system on two successive Sunday services for everyone to judge. The reaction was like night and day.

“We replaced 32 speakers,” Redman continues, “whose intelligibility was very poor from front to back and across the listening area.

Vocal clarity was key here because there’s a lot of reverberation in the room to enhance the 50-member choir and organ sound.”

The rest of the system, designed for easy operation, consists of Crown amplification, along with Allen & Heath iDR8 rack-mount digital signal processing system and two PL10 control panels.

Bottom line, “OmniLine delivered the best sound distribution for the least investment. People can finally clearly hear the leaders no matter where we sit,” Redman concludes.

“As it turned out, these two small arrays solved the problem one hundred percent.”

“People in the front could hear as well as the ones in the rear and it sounded even from front to back for the first time. And they’re light, really small and easy to rig.”

Schofield, impressed with the system’s intelligibility, adds “once we chose the Martin Audio system, we’ve been thrilled with the sound ever since.”

“To the extent that St. David’s is now attracting really big musical events, such as the Philadelphia Boy’s Choir Christmas Concert.”

“It was fantastic. We had the City choir the week before and they loved it too. This has become a popular venue for choral concerts and presentations.”

Martin Audio Website

{extended}

Allen & Heath Releases Updated iLive Firmware And Editor Software

Version 1.6 packs numerous feature enhancements and updates.

Allen & Heath has released the latest version of its iLive firmware and Editor software, which includes a range of enhancements. Version 1.6 is available immediately and can be downloaded from www.ilive-digital.com.

These include support of the new iLive-R72 Control Surface, Dual-Rack input expansion, and ‘SuperStrip’ user view in the Editor control software.

Among the many new developments in the offline/online Editor control software is the ‘SuperStrip’ processing view, which combines important live mixing parameters into a single window, enabling a more comprehensive view of functions when configuring offline or mixing live.

Another key feature in v1.6 is the ability to set the redundancy socket on Allen & Heath’s Audio and Control over Ethernet option card as a breakout to split to other iLive systems, offering a cost effective alternative to audio networking.

There are an array of feature enhancements to improve flexibility, including a Range Select patch function for easier set up of FOH/Monitor/Recording applications, and Safe mode for DCA master levels and mutes when recalling Scenes, ideal for festivals or events involving multiple band set ups.

Allen & Heath Website

{extended}

Minnesota’s Eagle Brook Church Expands Audio Infrastructure With Multiple DiGiCo SD8 Consoles

DiGiCo SD8's were chosen to improve functionality of their audio system on their main campus.

Minnesota’s Eagle Brook Church is a thriving, dynamic house of worship which has grown from 300 people to over 11,000 parishioners in its 60-year history.

As well, the church has grown in physical size, expanding from one to four locations, with a fifth slotted for the near future.

Due to this tremendous growth, the technical infrastructure required a retooling. Last year, Eagle Brook’s primary main campus console, which was handling FOH, monitors and video broadcast production, was replaced with three independent DiGiCo SD8 consoles.

Audio Logic Systems’ Jason Kartak was Senior Designer on the project—working in tandem with Eagle Brook’s Director of Technical Arts, Bill Berger.

“As a client, Eagle Brook came to us when they needed to upgrade and get better functionality out of the system for their main campus,” explained Kartak. “This improvement was in conjunction with two other building projects they were doing, and to better improve the video audio which is broadcasted live to their other 2 campuses.

“I had had previous experience working on an SD8—our production department owns one—and I fell in love with mixing on it. The availability to have dynamic EQ and multiband compression will help them define their mixes and take them to another level. Along with the SD8’s impressive sound FX onboard, its sonic quality and feature set for the cost was outstanding.”

“After doing some research on what our options were, we decided to demo the DiGiCo SD8,” Berger recalled. “Having seen the console in action, I decided that the SD8 would take Eagle Brook into the future. The SD8 has a much warmer sound than our previous console, but perhaps the best feature I appreciate is the ability to link all three consoles together.

“Everyone loves it,” Berger added, “and the sound is incredible.”

DiGiCo Website

{extended}

Central American Events Company Invests In iLive

The iLive-T112 was chosen due to its easy learning curve and digital flexibility.

Honduras event and AV rental company Comunicaciones Mango BTL recently added a new digital console to its hire stock, selecting an Allen & Heath iLive digital mixing system to complement the company’s existing Electrovoice PA and DAS PA Line Array.

Mango purchased an iLive system comprising an iDR-48 MixRack and iLive-T112 Control Surface through Allen & Heath’s distributor, All Music Corp.

Based in the capital, Tegucigulpa, Mango provides event management services for a client list that includes Unilever, Pepsico, Tigo, Bimbo and Cerveceria Hondureña.

“We started using digital consoles three years ago and we love the flexibility digital gives us as we can carry less equipment.”

“Recently we decided to invest in a digital console with at least 48 channel capacity,” explains Mango’s Andre Ferrer.

“Our first choice was the Yamaha M7CL but following a demonstration of the iLive-T system by All Music Corp we decided iLive was the right choice due to the flexible digital snake and easy learning curve.”

“iLive is very versatile, which means I can apply it to all genre’s of music, from tropical to extreme metal, and it is great to use for FOH or monitors,” reports sound engineer, Rafael David. “The preamps have nice headroom and I love the gate, compressor, and the flexibility of the process chain.”

Allen & Heath iLive Website

{extended}