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Posts Tagged ‘Passive acoustics’

How to use Cardboard Tubes to Fix a Church

Posted by jdbsound on April 1, 2019

Acoustics – complicated to figure it all out, simple to implement. First of all, this is a system, not a spot treatment.  Therefore, all of the walls of a room require treatment.  This is true for all acoustical artifacts, but most products are not able to solve multiple room problems.  As a result, most churches wind up getting only a spot repair treatment of which they learn later was nothing more than trading one problem for another.

To begin, you need a detailed analysis of the room.  Some of the critical measurements are impulse responses,  series of ETC’s and the Frequency response of the room.  These tests combined with others help to map out the room.  With these details, you will be able to identify the standing waves and what frequencies are coming out of corners.  What surfaces are diaphragmatic and where the room focal points are. Finally, you have to account for the room measurements to see if any of the dimensions are causing patterns in specific frequencies and any hotspots or deadspots.   

With this information at hand, you can then create a profile to identify what kind of treatment the room needs.  For standing waves, any diffuser can get rid of that as long there are at least 4 inches of deflection and no surface of diffusion greater than 6 square feet. If you go larger than 6 square foot diffusers, then you have to make the deflection more than 5 inches.  Learned that from trial and error testing.  There is no equation that I am aware of that will tell you that.

Once you have determined all of your standing waves and yes, all rooms that have no acoustical management, regardless of shape have standing waves at some frequency or range of sounds. You then look at the energy coming from any diaphragmatic surfaces (drywall, wood, windows, etc.) and corners. If the excess frequencies are above 500 hertz, in most rooms, you can just use 8 inch half rounds. If there is excess energy between 300 to 500 hertz, then you need to use 12 inch half rounds.    When there is excess energy below 300 Hertz, then you will need 16 inch half rounds.  

With this knowledge, you then need to see how much reduction is needed.  If you only need 10 to 15dB of reduction, you can just put in the half round tubes in 11-inch spacing between tubes regardless of size.  If you need more than 15dB of reduction, then you need to use patterns.  These patterns can be a combination of sizes and variable spacing distances between the tubes.  These variables cannot always be used depending on how much wall space you have.  If you have the wall space and you need more than 30dB of reduction, then you need to use a Prime Number sequence and enough wall space for a minimum of two cycles. 

These patterns were researched by myself by doing a series of trial and error testing in churches where the church allowed me to use their worship space to do experiments.  With enough tubes of various sizes, these tests were done over several days at a time, to learn what patterns are needed for the most common acoustical problems most churches have.  Essentially, I created a Data Base of models to affect the best change for worship spaces of all sizes.  For some churches that present a new problem, JdB Sound Acoustics owns a private test room where research can be done to discover the best pattern to effect the best solution for such a worship space.

In summary, there is no shortcut to doing church acoustics correctly.  That said, many churches can’t afford to hire an expert, but they also need help.  For those churches, several basic rules always assure a huge room improvement. The length of the tubes has to be a minimum of 2/3rds the wall height.  Sidewalls need the diffusers to be 4 feet off the floor or head height of people sitting in the pews.  Tube spacing is always 11 inches between edges. End caps are needed at the bottom to comply for fire code if you are using hollow tubes.  Follow these rules, and you will always get better results than any flat absorbent panel can offer. Another rule is, always have padded seating and carpeted floor.  In most cases, that gives the room the behavior that it is 50% full when it empty.  If you don’t have carpet on the floor, then you need to add absorption panels that equal the square feet of the floor space to the walls along with the diffusers.  If your wall space is limited, you can add the diffuser on top of the absorbing panels.

Every room has the same or similar problems when it comes to church acoustics.  The solutions and tools are always the same but how they are implemented needs to be customized to accommodate the architectural features each room has.  I have come across a few churches that followed these rules without my help, and they were delighted with the results. Yes, there was room for improvement in those DIY projects, but the results they got were way better and cheaper than any other solution out there.  Imagine going to Home Depot or some other place, buy around $1,500.00 worth of cardboard tubes, paint, tools, and hardware to mount the diffusers and fix the acoustics of a 500 seat church for under $2,000.00.  A project like this can be completed in 4 days with four volunteers.  If you make absorbing panels of sufficient quantity, you will spend twice as much if you care for the aesthetics and have a fraction of the room performance improvement compared to what half-round tube diffusers or Tube Radiators can provide. 

In the end, a 15dB reduction in the mid-range, getting rid of standing waves and because the tubes break up energy traveling down a wall, there is no bass build up in corners, so you don’t need bass traps, the room improvement will be very dramatic.  My skill comes into play for churches with strong music programs for contemporary worship services or large choirs.  Churches that want their pipe organ to have a better balance during congregational singing or for Choral performance.  Churches that want  congregational singing to be loud enough to drown out the sound system.  Then there are churches that have a lot of windows, artwork or limited wall space, for them, there are many other ways to achieve similar results using other diffusive materials and techniques that require a more substantial investment.  In many ways, most church problems are the same, but they all have unique variables that need different ways to implement the same solution. 

Finally, why do I use this system?  It is because of God.  God showed Solomon how to make the acoustics of the temple ideal for the Holy of Holies and the main sanctuary.  I discovered that this does indeed work.  Since re-discovering this method of sound management, I have viewed this as a promise from God.  How many times does it say in the Bible follow these command, instructions or ways, and you will be blessed or things will be better? Since learning this method of managing sound, God has kept his promise every time.  Also, consider this. 

Science has yet to create a simulation model that can accurately predict the results.  God told Solomon what to do, and this method does work.  All of the 400 plus churches that are already using this method of sound treatment, they did it as an act of faith whether they realized it or not.  I have always been honest in sharing this with everyone.  God has kept his promise to all of those churches. For those who want proof, isn’t 400 plus churches of all shapes as sizes enough?  You don’t have to believe me, but you should believe God. Since this is proof of what God teaches in the Bible is true, what does that say about the rest of the Bible?

If you don’t trust the science, if you don’t believe me or this website, you can trust God in this.  God showed me how to do church acoustics, and the answer has always been out in the open, in the Bible for everyone to read it.  The shape of the sanctuary and the acoustical treatment are all there for us to follow.  Furthermore, Jesus was also present when God told Solomon what to do.  In a way, Jesus told Solomon what to do also, as you can’t separate God and Jesus.  When God speaks, Jesus speaks. 

This method of doing church acoustics is not a secret or a mystery.  It is there for everyone to know how to have the best worship spaces that Christians need and is a joy to have.  So if someone says, “that is in the Old Testament, and it is not relevant today.” I say, Jesus said he came to fulfill the laws, the prophesies and promises that He made in the Old Testament before He became flesh.  We are supposed to follow His ways because we love Him.  We Love God.  Because we love God and Jesus, we follow the teachings of the Bible. For far too long, we have been using secular designs of worship spaces and acoustics at the expense of not knowing the full blessings of worship God wants you to have in your church today.  Worship space designs and acoustics should never be treated as an option or another failed experiment when it doesn’t have to be that way.  If you know the scriptures, you know that this is true.

Sure, for years people have been blessed in houses of worship in all kinds of shapes, sizes, and acoustical problems because of their faith.  Fixing the acoustics of existing churches in this method has huge benefits right away and for the future.  However, only a few of them are experiencing all of the blessings God promises us when we follow His ways, including worship space designs and acoustics.  You could also say that a House of Worship is also another tool used to do a better job at fulfilling the great commission when designed according to His way. God will never stop loving us or blessing us when we make mistakes, but he did say we reap what we sow.


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The Best Worship Experiences

Posted by jdbsound on March 25, 2019

What would you prefer? A church were you can have the best worship experience or a church that looks amazing?

The organist of this church pulled every stop, pushed the peddles all the way down and the he had trouble hearing the organ just 20 feet away. At the back of the church at the sound booth, the organ was barely audible. I used a SPL meter, put it about 3 feet over my head at the back of the church and the congregational singing peaked at 105dB several time during a familiar hymn. There was no one behind us. There have been other times at other church where I designed or upgraded their acoustics were the congregation is singing acapella and they were peaking at 106dB. The good news is, singing like that doesn’t hurt your hearing.

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Church Sound and the Gospel

Posted by jdbsound on January 28, 2019

The goal of any worship space and the church sound system is not about loudness, gain before feedback, intelligibility, special sound effects for the organ or choir, having the most talented performers in the worship team, how many wireless mics, number of channels the mixer has or the name brand of equipment you have. The goal of a church worship space and the sound system is to be a safe place where the Gospel can be presented clearly and with little to no blemishes. Where every person within the worship space can hear and understand the Gospel as clearly as when having a conversation with someone only 4 feet away and sharing the Gospel. Anything less than that goal means that the spoken word can be corrupted in the journey between the minister’s mouth and ears of all those who are listening. The Gospel needs to be broadcasted and understood as clearly as reading God’s written words.

If your church has hot spots, dead spots, good sound in these seats and poor sound in those seats, then the Gospel is not being presented equally to everyone. If your sound system has technical problems during worship often, then it is a distraction, and it can make the difference of understanding something important.

The chart below shows tangible results when your worship and sound system are tested. There should be three tests.

The first is with a test speaker. It is a point source speaker that is small enough to mimic a person’s voice.

The next test is feeding a signal directly into the sound system and test those results. This test is just about the playback quality of your sound system.

The third test is to use the test speaker 30 inches from an open microphone such as a pulpit or any microphone on a stand and test the combined results of the worship space’s acoustics direct interaction of the sound system and open mics. You can also do a second version of this test and place the test speaker 4 inches from a microphone where the microphone is 45 degrees off axis.

If all three tests are not in the Yellow section, the results will let you know if it is your sound system, the acoustics or all of the above.  This is also a better indication predicting if upgrading your sound system will improve the results you are looking for. This is also a strong indicator that your worship space needs some kind of an acoustical management system

sti alcons chart conversion

You can get your church tested. It doesn’t cost much, and the results can save a life or many lives, depending on your point of view. As an independent consulting company, we offer church testing and results with no obligation to use our services in the future.

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What will give you the biggest bang for the buck in upgrading the Sound of your church?

Posted by jdbsound on May 2, 2018

This 300 seat church already had a reasonable high-quality sound system.  It was properly designed for the room and professionally installed. The acoustics were not that bad.  At least it was thought that the acoustics were not such a problem.  The outstanding issues they were trying to solve or improve were:

  1. Gain before feedback,
  2. Elimination of the few deadspots that were not solved from the previous sound system when the current new JBL speakers were installed
  3. Reduce sound spill from floor monitors,
  4. Better control of the drums (when using acoustic drums) and
  5. They wanted 3dB more bass from the Sub-woofer.

These are all reasonable reasons to upgrade the sound system.

Good Speaker System setup_s

The church was considered the following upgrades.

  1. Replacing the professionally designed and installed 12-year-old JBL sound system.
  2. They considered going for IEM (in-ear monitor) system for up to 8 people. (This would have included a new digital mixer)
  3. The church considered making an air-conditioned drum booth or get an electronic drum kit.
  4. They also wanted to add a second twin 15-inch sub-woofer.
  5. Estimated total cost, almost $26,000.00 installed.

This is what the church actually did. They changed the acoustics of the room.  They installed an acoustical Tube Radiator system.

What did they gain by doing this?

  1. The sonic quality of the existing JBL speaker system was greatly improved. The improvement was noticeable better regardless of how much equalization was added or when the EQ was bypassed. (Definite proof that the acoustics of the room changed the performance of the speaker system from the day they were installed.)
  2. All of the remaining deadspots were now gone. (This was never a speaker system problem as the right speaker system design was already installed.)
  3. The performance of the speaker system was such that picking up a person’s voice went from 12 inches to 35 inches with a Shure SM58 mic before feedback would show up. (Again, acoustics limits the performance of all sound system. Sure there are some very expensive gadgets that can improve gain before feedback, but such gadget can cost more than the material cost of the acoustical fix.)
  4. The floor monitors are now well behaved. No matter how loud the floor monitors get, you definitely need to and to add the front of house to hear clear sound. As it turns out, the overall stage mix dropped around 10dB without the performers even noticing as they were now able to hear the stage mix from the monitors so well at a lower volume. You could say that the monitor spill issue is eliminated.
  5. This eliminated the need for IEM’s.
  6. Since the drummer can hear himself now, he gradually started playing quieter after a few weeks. The need for a drum cage disappeared.
  7. The Single Sub-Woofer was now able to play 9dB louder without distortion. It would have taken 3 more sub-woofers to get the same loudness without distortion. That was equal to spending around $15,000.00. (Standing waves and bass buildup in the corners added air pressure onto the surface of the cones of the subs drivers. This added air pressure creates distortion. When the subs distort, the sound quality and maximum sound levels of what the sub is supposed to be able to do, can drop up to 15dB in many rooms.)

Aylmer EMC Church Pano 2017_ss

Other improvements

Congregation Singing.

  1. The participation of people singing went up from 30% to 75%. (When people can hear themselves and the other people around them, it encourages people to sing more.)  s a resulting, the congregation is singing 8 to 15dB louder. (The more people singing, the louder they will become.)
  2. No more distortion from the speaker system with playing louder which means the perception of loudness is greatly reduced. (Standing waves and bass buildup in the corners added air pressure onto the surface of the cones of the bass driver of full range speakers. This added air pressure creates distortion. When the bass drivers distort, the sound quality and maximum sound levels of what the full range speaker is supposed to be able to do, can drop up to 15dB in many rooms.)
  3. After two years, the congregation is starting to add harmonies to their singing. (That is what happens when people can hear each other.)
  4. Now when people stand up to give testimonies or prayer requests, people can hear them whenever they forget to use hand-held wireless audience microphone.
  5. The front of house stage mix is so much better. Now you can hear all of the performers without having to blast the sound system. (A well-diffused room can make the signal to noise ratio improve from 3dB to 25dB. As the signal to noise improves, the easier it is to settle into a high quality.)
  6. The worship space is now concert quality for any high SPL event, recitals, choirs or orchestral events.

The total cost of the acoustical system including painting the whole sanctuary. $1,400.00
Since this as a DIY project, the money saved went towards a better headset mic for the pastor and the new digital mixer. Total upgrade, $5,000.00. If the church contract out the installation of the Sono Tubes, add $5,200.00. That is still 60% of the cost of upgrading a perfectly good sound system if everything is contracted out or an 83% difference.

Conclusion

One can honestly say that fixing the acoustics had a far better return on investment versus just upgrading the speaker system alone. Upgrading the speaker system can never make the room sound better, improve congregational singing and it would have not been possible to delete the deadspots without adding more speakers on delays around the room. This transformation is typical of the new worship experience when a church gets the acoustics they are supposed to have. In the battle between acoustics vs sound systems, acoustics always wins. It’s Physics. Try moving a wall with air? You can’t. Change the wall and hear what happens!

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Dead Spots – Sound System or Acoustics?

Posted by jdbsound on April 9, 2018

An unwelcomed guest in any church is Mr. Deadspots. Unfortunately, deadspots in churches are more common than you think. There are two main types of deadspots. Some are frequency related/comb filtering interference and others are dips in sound levels greater that 6dB created by the room.

It is common to see frequency related deadspots in Left/Right sound system regardless if they are Line Arrays or point and shoot speakers. These deadspots are created by interference patterns in a mono speech system as a persons voice is always mono.  These deadspots are where you shift from one foot to another and notice a sound change. In these cases it becomes a problem when on one foot you hear the highs but not the lows. When you shift your position onto the other foot, you hear the lows and the highs disappear. People with hearing aids or early stages of hearing lose notice this the most. People with good hearing notice the change too but learn quickly to put up with it. Some young people think of it as a passive noise filter. If the music is too bright, stand to one side of your seating position. If the music is too boomy, shift to the other side of your seating position. Really! Isn’t that like buying a headset and controlling the sound changes with what angle you tilt your head. It might sound like a great idea until you find yourself with a lot of neck pain. No thank you.

Sound level dips are usually acoustically related. These are created with standing waves, bass building up, hollow walls, room corners, and parallel surfaces that include walls, ceilings and floors and concaved surfaces. In all of these cases, often mid and bass energy build up and the highs are absorbed with carpets, padded pews and people. By the nature of churches and how they are used, carpeted floors and padded seating often represents how the church sounds when it is 50% full. That means that if your attendance is often over 50%, the effects of padded seating and carpeted floors has little to no impact. If church attendance is often over 70% a carpeted floor makes the room more intimate during times of prayer and solemn reverence. In the end, carpets and padded seating is a good thing.

However, because of people in the room, once that room attendance is above 50% the people absorb enough highs that extra mids and bass energy is left behind as is being amplified between parallel surfaces. This excess energy automatically masks the highs. When the highs are masked, speech and music intelligibility drops. The kicker is, if you go around the room with a sound level meter, often the sound levels don’t drop much, even when you stand in a spot where the highs (when you measure just the highs) drop off over 6dB. That is because the excess bass energy is so strong that it fools the sound meter as the meter is reading an average sound level. When you take sound level readings by frequency, then you notice the high number of deadspots in the room. Get a tone generator in a cell phone or computer app and play a constant tone at 55dB at 500 Hertz, 1000 Hertz and 3000 Hertz and then start walking around. At 500 Hertz you shouldn’t notice much of change until you get close to walls. At 1000 Hertz you will notice more changes. At 3000 Hertz, if you are hearing a lot of changes, imagine what 25% of your church audience is experiencing.

Here is a church that had both acoustical and sound system created deadspots, with a central cluster. By nature of a central cluster, in a good room, it gives the best coverage and performance for speech. There is no better way to design a church sound system unless your ceiling is less than 14 ft. high. Choice of speakers, coverage patterns and speaker placement impacts sound too but these are mainly tone qualities and gain before feedback related. It may have up to a 2 or 3% impact on overall intelligibility as well.

corner view pano Ebeneezer Church_s

In this church example, it already has a fairly good quality speaker system in the ideal location for the room. It is designed as a central cluster and by nature, in this setup, it should perform well. However, it didn’t matter if you used the main speaker system or used portable speakers on stands, with any sound amplified you could find deadspots all over the room. On top of that, if you raised your voice in the room, once you were more than 18 feet from someone, understand what was being said was difficult to impossible depending on dictions of the person talking and how good is one’s hearing. When the proper acoustical fix was applied, all of those problems went away and the church didn’t need to upgrade the speaker system.

The church decided to leave the sound system alone as the gain before feedback improved and all of the deadspots disappeared. Since this is a traditional church that has no intentions to do anything contemporary, the acoustical fix was designed to not change the overall reverb time. Before and after reverb time remained about the same. 1.7 seconds.  It was the frequency response of the room that saw a major change. As the graphs shows below, where the mixer for the worship space was located, it was also one of many spots where weird measurements were recorded before. We found dozens of spots where the room measurements went squirrely. This is typical of the results of measuring a Left/Right speaker system, not a cluster system. These weird results were a result of room acoustics and not the sound system.  We used our own test speaker for all room testing.

Sound Booth Before and After

After checking our test equipment for errors, it was then realized that by just moving the mic over a few inches, you would get a very different result. In some places, the sound was perfectly fine but move over a few inches and it was not. Our ears are about 8 inches apart. In one row of seating, the largest distance we could move the test mic between a good spot and bad spot was 14 inches. Pew seating is 18 inches.  Every seating position had both good and bad sound. What we were measuring was sound masking in the mids and lows.  The energy was so strong that it masked the highs.  Not only that but the highs were most likely also being canceled from nearby wall reflection between 1800 to 5000 Hertz.  It gave the impression that there was something wrong with the sound system.

In this church, people marked their seating positions by placing personal pillows in spots where the sound was better. Sure enough, testing these spots showed better sound before the acoustical treatment was applied. After the acoustical system was installed, the sound was the same no matter where you sat including the sound booth.

Deadspots in churches are more often a result of worship space design and not a result of sound system design (unless you have the wrong speaker system design for your room). When a church replaces a well-designed sound within 10 years, and have little to no overall improvement after an upgrade, that should be a BIG RED FLAG that you most likely have a serious acoustical problem and no amount of money spent on the sound system can make those problems go away. Besides, these days, acoustical fixes cost less than sound system fixes. As a caveat, our experience has been this. Churches that have fixed their acoustics and then wanted on to expand their music programs, they were able to upscale their sound system with a much higher budget as they upgraded, it actually lead to better performance rather than an exchange of one set of problems for another.

Bottom line is, get your church properly tested. Have someone who knows how to properly diagnose the data, and then design your church a proper acoustical management system. Install the acoustical system and watch the congregation respond and grow. Don’t be surprised if other churches want to use your church for musical and recording events. Your property value may go up too.

Note – The acoustical system is made up of 8 and 12 inch half round plaster covered foam diffusers on 3 walls.  The side walls use a gradient pattern to maximize room performance. On the back wall there are 24 units of 7 ft. x 2 ft. x 18 inch plaster covered foam diffusers that are hollow which allows for additional passive room equalizing in the near future. Project completed by church members.

By Joseph De Buglio
JdB Sound Acoustics

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What is the difference between scattering sound and diffusion of sound? Are Diffusers Programmable?

Posted by jdbsound on April 26, 2015

The simple answer is as follows.  Half, quart or third round devices or objects individually just scatter sound.  A single barrel diffuser or tube radiator as I often call them just create a very uneven distribution of sound.  As single units, it gives about the same amount of performance as placing a flat object of the same size and placing at a 15 to 35 degree angle on a wall.

When using barrel diffusers in various sizes and/or in spacing varying from 0 to 30 inches and apply them to all of the walls in a confined space, you are creating a diffusive field.  You’re turning the church walls into a phase coherent sound field – like churches of yester year built between the 1400’s to 1700’s.  When barrel tubes are used as a system you can program them to only manage the acoustical problems you want to get rid of and at the same time create a more desirable sound field like real reverberation that is musical and supportive to congregational singing.

Barrel tubes spaced too far apart just scatter the sound and reduces some bass but does nothing much else.  Instead, you can program the diffusers to manage standing waves, bass buildup, notch a frequency or two and equalize a room.  You can also program them to lower stage noise, manage monitor spill into the audience and improve congregational singing.  They can also be programs to make the sound system perform better.

The software to program barrel diffusers is still in development.  In the meantime, a test room, and a data base of real world testing is the best way to predict the final outcomes.  Try and program a digital EQ to cut 350 hertz 40dB.  It can be done but it sounds awful.  When you program tube radiators to cut 40dB, it sounds sweet.

Joseph De Buglio

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