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AVL Designs Inc. first became involved with the Liverpool Central School District in 2007. We were asked to investigate echo problems in their auditorium. When someone would play a snare drum or any other percussive instrument on the stage, you could hear 7 to 12 discrete echoes that were hard to miss. It was like bang…… bang, bang, bang, bang, bang, bang, bang. Of course, this was a problem. The echo occurred in certain areas of the room, not every area of the room, but it was so noticeable that this defect got in the way of most musical performances.
We corrected this by testing the space and then placing specific acoustical panels on sections of ceilings and side walls, effectively eliminating those echoes. When you add absorption to a room, you lose some of the liveness. It is an inevitable trade off when getting rid of the echoes. You lose some of the reverberation.
In the process of time, we talked with the school district about other corrections that were available in the realm of electronic acoustics, which we have done successfully for other schools. After meeting with the music department, we decided to implement an electronic acoustic system in the space. Due to budget constraints, it was ceiling installation only. No side walls, no stage shell, but it was designed to allow a much more immersive sound quality for certain kinds of music.
The room was lacking low frequency response. The reverb time was around one second in the midrange, and it needed the ability to go to higher reverberation times for certain styles of music and types of theatrical performances. Once the system was installed, the school was thrilled. They were so enthused about it that they became a major proponent of this technology, sharing their experience with other schools we met with in the future.
As 2016 arrived, a major renovation was planned for the Liverpool Schools. They were enlarging the entire auditorium, refurbing the music department and adding some additional rehearsal spaces. As a result of our prior experience and success with their existing auditorium, AVL Designs Inc. was brought in along with the architect, on the early stages of this project.
Electronic Acoustics added almost everywhere.
There were a number of goals for the project, the first of which was to include electronic acoustics in many locations. It would not only be the in the auditorium and on the stage, but also in the large rehearsal rooms for orchestra, band and choral ensembles. That way the singers and musicians would be able to rehearse in environments similar to what they would experience in the auditorium.
So, that became the initial driving force for the acoustical design. We had to look at how to treat the main auditorium to get the reverb time low enough and flat enough that when we implement the electronic acoustics, there will not be significant problems with frequency balance and reverberation curves.
The electronic acoustics system is based on Yamaha acoustic field correction devices. It is implemented with speakers located onstage, in overhead ceilings, in under-balcony ceilings, and on sidewalls. These systems are providing reverberation as well as early reflection support for the room. The system can also add voice lift to allow for events without sound reinforcement.
Bigger auditorium, curved walls and NEW balcony.
The auditorium was being dramatically enlarged, shaped with curved walls plus adding a balcony. To deal with that condition we developed a custom absorptive diffusive wall treatment. It consists of series of wells of different depths with perforated materials and solid materials, creating a diffuse sound field within the auditorium and generating a relatively low reverberation time for the size of the room. This design criteria was also used for the music spaces to produce similar reverberation curves for their base conditions. That way, when the electronic systems are commissioned, there will be tunings for each space that will mimic each other to the degree that you can mimic a smaller space to a larger space. In addition to the electronic acoustics and physical acoustic designs for this auditorium, AVL Designs Inc. was contracted for stage rigging, theatrical and house lighting, and sound and video in the space.
Huge Speakers? Here’s why …
One of the unusual features of the room is the incorporation of Danley Jericho loudspeakers. The Jerichos look huge and indeed are huge, but they are actually a replacement for line array technology that many auditoriums would implement, at a lower cost and a higher performance level. The Jericho combines a large number of drivers in a single large enclosure, creating an output pattern and sound pressure capability similar to a 12 element tall, mid to large scale line array.
Admittedly, it looks a little odd to have boxes this big in a high school auditorium however the pattern control over the wide frequency range of the speaker allows it to cover most of the main floor as well as the balcony without the need for other devices.
*We did, however, install over and under-balcony delay fill speakers. This was primarily for potential special effects for theater use, and also to add the few frequencies that would be missing as you go by distance to the back of the room.
The audio system is being fitted with an Allen and Heath D Live console, which is a substitute for a Yamaha console originally specified. (Due to Covid issues the Yamaha console is not currently available) The D Live is a great console and will do a fantastic job for the school in the new application.
Theatrical lighting consists primarily of Electronic Theater Control products and High End systems, with some Strand and Phillips fixtures as well.
Stage rigging is a combination of Brick House counterweights and Electronic Theater Controls Prodigy hoists. The Prodigy hoists are used for onstage electrics, as well as a front of house moving head electric.
All of the music rooms are used as green rooms, so we have a combination of intercom, call lights, and video feeds to each of those spaces from the main auditorium.
Quite a few of these systems are not fully online due to product availability problems in the current post-Covid world that we are living in. We hope to get all of them online toward the end of the year. The owner is very impressed with the space currently. They will be really excited when all of the final details are worked out. The transformation from the original room to what it is now is dramatic.
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When the Burnt Hills Ballston Lake High School made the decision to renovate their auditorium, the architect requested that AVL Designs Inc. join their team. This appeal was initiated by the owner who had been involved with another AVL Designs Inc. project at a different school. AVL had designed the performance systems which worked so well that they wanted to have us involved.
During the schematic phase, it was determined that the auditorium would have to be entirely gutted. The space would be converted to a “black box” style space with the addition of a balcony and wrap-around catwalks with lighting positions.
Room acoustics were to be managed with the use of electronic acoustic systems. For electronic acoustics to succeed, there must be very low noise in the space, and an acoustically neutral response from the room itself. AVL incorporated acoustical absorption on the roof deck and walls to control the room response.
Working along with the mechanical engineer, AVL Designs Inc. was contracted to do ductwork noise modeling. The final system is so quiet that it is inaudible.
Audio systems include an Allen & Heath Avantis Console, Danley Loudspeakers, Ashly Audio DSP and amplification, and Shure QLX D wireless systems.
Video includes projection as well as LCD screens with controls by Crestron and Blackmagic Design, and Robotic Cameras by Panasonic.
Lighting is based predominantly on products from Electronic Theater Controls, Hi End Systems, and Strand Lighting.
The electronic acoustics system is based on Yamaha AFC. Due to covid delays, the commissioning will be this fall.
Covid related product delays also forced AVL to assist in coming up with workarounds as some products will arrive 6 months or more after the facility begins to be used. Such is life these days, but workarounds are getting the job done.
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So today we’re going to talk about a subject that kind of drives us crazy: acoustical doors.
In our experience over the years, we we’ve designed a lot of projects. We’ve worked on many projects that called for the use of acoustical doors. Quite often, acoustical doors don’t work properly in the field. The ones that we specify are magnetically sealed, and they tend to work quite well. The ones that are compression sealed, however, do not.
Most recently I was asked by an architect to do some testing on a project that we did not design. There was a compression sealed door substituted for a magnetically sealed door. It was testing at NIC 38 but it was supposed to be a NIC 50. Why was that? Well, the door simply could not get enough compression to seal the seals.
The results in this instance were so poor because they were using a card swipe access system that would not allow that amount of compression. So, the customer was paying for 50 and getting 38, which is a dramatic loss. 10 Points is twice as loud……
And in this particular example, it was a vocal isolation booth, so it was a big deal. What they needed to do was change the seals out to magnetic, which can be done in the field. It is an added cost and obviously contractors would be involved. Since it was not our project, we have no idea what they finally decided to do about it.
Why Mag Sealed Doors?
So, what I want to talk about is why magnetically sealed doors are used.
Our first example is your refrigerator. Your refrigerator has a mag sealed door on it because you want to keep the cold in and keep the heat out. Acoustics are the same thing. A magnetic sealed doorframe, like a refrigerator door, reaches out and grabs and the refrigerator frame, and that keeps the door closed.
In the case of a door that is used by the public, it must meet ADA* requirements. The door must have the proper opening effort to meet ADA. There are some magnetically sealed acoustical doors that do and there are some that do not. *ADA: Americans with Disabilities Act of 1990
When you get beyond about STC 48 or so 50, you must go to a double magnetic seal. Most of those will not meet ADA requirements and would then require something like a motorized operator to open the door. But if you want high performance doors, you are going to be into double or triple magnetic seal doors and they are not going to meet ADA. Good as they may be, they are not always usable.
We’ve had some clients who have chosen to go with compression seals because of the opening force, but they are most often 10 dB lower than their rating because they don’t compress.
We show you something in this video (starting at about 3:00 on the meter) as we look at a door online and kind of walk through how it is assembled and the type of performance that you can expect out of it, if it is properly installed.
Our base spec is always centered around IAC Acoustics because of our experience with them in the past. (A picture is worth 1000 words, right? Well, In the video above you will see this and other examples and we explain them.) This door is an STC 43 but we have had field performance from this door closer to 47. Now they won’t rate it that way because they are very conservative, but we have had a bunch of these in the field for quite a while and that has been what we have observed. Not only have these acoustic doors performed higher than the official rating, but they have also continued to perform that way as time goes on.
So, why do they perform so well? First of all, they are built completely assembled with hardware delivered. So, the contractor can simply set the door in place to the threshold and the walls and it is done. No one has to put assemble hardware in the field.
This door also uses a cam-lift hinge system. So, the door rises up in the air as it is opened so that it lets a yield pad compression seal at the bottom expand and then it compresses as it drops. You’ve got the magnetic seal around the perimeter which really is a very high performing seal.
Double Magnetic Seal Doors
Now let’s talk about situations where you need something beyond. In these cases you will be getting into a double magnetic seal door.
Again, it is kind of like your refrigerator. When you go to pull it open with a single magnetic seal, most people can open it, no problem.
If you had a double magnetic seal, and then added to the that a cam lift hinge raising and lowering the door, you might not be able to get your refrigerator open. You have probably seen small children who cannot open the refrigerator, even with a single magnetic seal.
Double or even triple magnetic seal doors are used in higher performance music spaces such as recording studios giving them up to way beyond 51 with a triple magnetic seal. The doors also weight 300 Lbs Plus.
Now, the reason I think they go with the double seals is when you get into these thicker heavy doors, you’ve got issues with potentially leaks around the seals themselves, possibly due to the doors. The second seal would be there to close that up. I am not really sure why they cannot do that with a single seal with a really heavy door, but everything above 51 tends to be double magnetic seal. Then the really high-performance doors tend to be triples.
A word to the wise with any of this is that if you really want a compression seal door to work, be prepared to have to lean on it with your body weight to close it. (also not ADA compliant) And then all of the tension when you do that is at the latch set. If your latch set here is you’re pushing and this is holding the door closed, it’s not holding it evenly around the perimeter. So you’re not necessarily going to get a compression seal that holds at the perimeter when all of your effort is at a latch set, which is where the mag seals come into place. The door is not being pressured to make it work.
So in our opinion, mag seals are the only thing you can trust. Everything else we’ve tested has been sketchy at best. We have tested many doors over the years, we’ve had one or two with compression seals that came anywhere close to their spec. It just happened to be a very perfect, pristine installation and there is no guarantee that they’re going to stay that way.
Do take a couple of minutes to watch our video. It includes further explanation concerning the compression vs. mag sealed door decision and you will see why acoustic doors DRIVE ME CRAZY!
We hope this post and video help you avoid a disappointing result (and the frustrating and often costly need to make corrections after) as you create a sound-isolated space.
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