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Sound System Design: Determining the Right Speaker for Your Space

While there are real and valid situations where line array speakers will work well in a worship space, I see this as probably the number one misapplied technology for optimal sound clarity.

It was summertime in the early 1990s… and Whiteheart was the headliner during the Sonshine music festival.  Being a teenager and loving to hang out with friends and hearing awesome music made for a great summer night.  

When Whiteheart was playing, there were storms that literally enveloped the festival grounds, as the thunder and lightning went seemingly in time with the music that was being performed on stage.  The river was flowing with God’s hand over us. 

From that, a passion was sparked in my life to pursue that kind of experience, not just that one time, but to where I could help with the audio and visual elements of worship. 

Turning the clock back even further, I had begun running sound at age 13, and was deeply technical well before that, having learned from dear ol’ dad.  

What had begun as a hobby, turned into a passion, one that has fueled a lifelong career. 

Alright, enough history … let’s get in to what makes for a good sound system. 

If you are interested in learning more about upgrading audio in your church, check out the following session, "Keys to Upgrading Your AVL," slated for the WFX Conference & Expo this November in Orlando.

Why does the room matter? 

With the music festival having been outdoors, there were a lot fewer acoustic issues to deal with, versus those that might arise from a room.  

Sound travels at 1,130 feet per second, and that is far slower than light.  This speed means that there is roughly 1 millisecond of delay per foot that the sound travels.  If your room is 80 feet from the front to back – you will have about 80ms of time pass, for the sound of you clapping on stage to reach that back wall. If the wall is acoustically reflective, though, then you will get a slap echo back at 160ms.  

See what just happened there?  Echo … Echo … echo … Yup, hard reflective surfaces cause audible reflections, and that can be problematic. 

What is the best solution for a room that has is burdened by too much echo?  Maybe pass out wireless headphones to everyone.  Or design a specialized sound system that can cut through it. 

One such “room” that at first glance has its own sound challenges, is the Basilica of St. Mary’s in Minneapolis. It has roughly five to six seconds of reverb time, with the prior sound system was comprised of large horns up in the attic, blowing through square grilles in the ceiling.  Fortunately, the sound was not directly aimed at the back wall but angled down. That meant the reflection was going to hit the floor, not bounce back up to the altar, which is an example of the angle of incidence versus reflection at work. 

Then 11 years ago, a large line array was installed at the Basilica.  

No, not that kind… 

What was installed were a series of 6-inch wide speakers that are each 21-feet tall.  At the time, this was very new technology, known as a digitally steerable array.  Essentially each individual loudspeaker driver had its own amplifier channel and DSP, to allow it to be “steered” by the processing.  The way it worked was by design, where a 4-degree beam of sound was disbursed out of each 21-foot array, with each speaker mounted just above people’s heads, as the beam was steered at a slight downward angle.  

This was a huge key toward the speaker’s performance, as if that beam was aimed squarely at the back wall, the reflection would have come back up to the altar about one-quarter second later, and really messed with the priest.  By opting instead to configure it with a down angle, that meant the reflection off the back wall ended up hitting the people’s backs in the last rows, while getting absorbed.  Remember that people absorb sound a lot better than stone or glass. 

Line Array or Point Source? 

This is probably one of the hotter topics that gets bandied about these days.  When I first attended the Sonshine music festival, the setup featured huge stacks of speakers on each side. More recently, though, those speakers have been replaced by huge hung line arrays.  

In the early days, we had loud sound up front, but as you got further back, it would get progressively quieter.  

These days, those on hand at Sonshine found it was as loud if they were back 200 feet from the stage, because the line array was huge, probably 16-20 boxes tall.  

One of the main attractions of a line array is that we are accustomed to seeing them at concerts, and that provides some validity to them being used in so many other setups.  

While there are real and valid situations where they will work well in a church, I see this as probably the number one misapplied technology for optimal sound clarity. 

Speaker Styles 

Let’s explain the basic differences.  A point source loudspeaker is just that – one loudspeaker that may have multiple drivers working in different frequency ranges to cover the full bandwidth of sound.  Most typical would be a 12-inch woofer and a horn tweeter.  Some may also include a midrange driver, and in the point source category there are several substyles.  This would be large format horn loaded, small format horn, coaxial and more.   

The large format horn loaded speaker is typically massive, and then the individual drivers typically produce their sound through the horn.  The horn is a device that helps direct where the sound goes, and the larger the horn, the better the speaker does at controlling middle and lower frequencies.  The smaller horn will only control high frequencies.  

To just say “I want a point source” is a statement that needs to be backed up with more information on choosing the proper tool for the job. 

The more reverberant the room, or the more you want to control the muddiness because of room reflections, then a large format point source speaker would be a better choice.  Not all manufacturers make speakers in such a configuration, but a few popular brands include Danley Sound Labs, Electro-Voice, Fulcrum Acoustic, and JBL

If a room is more acoustically dead, it should work fine with a small format or coaxial style speaker. That is because you don’t have to contend with the problematic reflections, one can “get away” with this kind of speaker. 

Considering Line Arrays 

When looking at line arrays, in the simplest way to describe them, they are a set of many “point source” speakers, designed to stack together and work together to make an array of speakers that “work together.” 

The reason for why I put the quotes around “work together,” is to make the point that there is both beneficial and destructive aspects of a line array speaker.  A perfect example of where the line works well, is where I want to have a long throw to the sound.  If the line array is long enough – and this is an absolute key point – then it will have control of the sound in the vertical plane.  Line arrays only control the vertical with the size of the array and curve, not the horizontal – that is controlled by the loudspeaker cabinet itself. 

The largest misapplication of a line array would be a room, with a very short front to back distance, and the line array being mounted high above the front rows with a big curve on it.  

That’s because let’s go back to the speed of sound… 1,130 feet per second.  Let’s get an imaginary string from the center of each individual line array cabinet, to my ear at the front row.  From my ear to the first box is let’s say, 15 feet, then to the second box is 16 feet, then the third box is 17 feet, and so on up the line.  

Walk back to the rear of the room, and do the same exercise. The strings at the back of the room would be almost equal distances. 

Where will the line array have maximum summation?  In the rear of the room – all the boxes will be relatively “in phase,” as compared to at the front of the room, there will be maximum smear of the time arrival, and therefore the most inconsistent sound from seat to seat as you go front to back.  As a result, there will be a lot of lobbing and poor consistency in the front of the room.  Imagine a snare drum.  How many times will you hear that drum down front?  With a line array of nine boxes, you will get nine pops off the snare, all within about 1ms of each other, and that causes a ton of comb filtering, and a “distant” sound to the listener.

 By comparison, a single point source box would give you just one pop of the snare, thereby offering an “up front” and clear sound.  As you get further back in the room, the point source will have a point where you are losing the coverage, and a delay fill speaker or a different approach may be needed to fill.  However, for many more modestly sized churches, the point source ends up being a good option. 

A point source loudspeaker can have both vertical and horizontal directivity, and if properly designed, a very consistent sound.  

But let’s go back to the Basilica.  

That room used to have a point source system, and then was changed to a line array … am I contradicting myself here? 

Well no, the speaker at the Basilica had the ability to digitally steer the sound, and we were within the sweet spot of its operation.  Line arrays absolutely are a wonderful tool.  I use them regularly, but my point here was more to make the statement that far too often, line arrays are misapplied because of their popularity in the marketplace. 

Which is right for your room? 

Unfortunately, if you haven’t figured it out, there is no clear-cut answer for all rooms. It depends. 

Should I handle the install of the speakers on my own? 

If you have the ability to critically analyze the room and its acoustics, along with the loudspeaker options, that could work.  

Be careful if someone comes along, though, trying to sell you on the new fancy line array for your 300-seat church.  That line array may in fact be a great solution, but there are cases that I have seen, where one ends up with spending far more money than required, for less than ideal results. 

What does system tuning have to do with the overall performance? 

Absolutely everything.  

As an example, contrast a beaten up old honky tonk piano out of a pizza parlor, compared to a new Steinway.  

Which would you prefer to listen to?  Right, I know.  

Now let’s say that the honky tonk piano has been professionally tuned and played, while the Steinway has not been either tuned or played by me.  

Now which one would you rather listen to?  Right, me too.  

In much the same way, having your system optimized is money well spent.  

There are churches I have gone to, where I have literally unplugged two of the five speakers in their space, and the church leadership was immediately amazed at the improvement in sound. 

TAGS: Gear
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