WXXI TV reached out to AVL Designs Inc. to design the interior acoustics and assist with noise control in their production 225 control room. They had recently purchased an AVID S4 Yukon console for the suite and wanted a control room that provided a better mix environment.
LIMITED HEIGHT The space is an unusual shape with some features that cannot be changed. The oddly trapezoid room with one glass door to the side of the mix position, and a large window to the live room that could not be relocated, was limited in height. It also had an electrical panel that could not be covered for code reasons.
NOISE The first order of business was HVAC noise control. The background in the space was NC 40+. Ductwork design was what you see in office spaces, not studios. Working with their mechanical contractor we determined to enlarge ducts, change diffusors, move VAV’s, and control velocities. The result ticks in at NC20.
LAYOUT The new space was to have a mix position and a client listening position in the rear of the space, where it narrows considerably in a “V”. To even out response, we determined to use high order quadratic diffusors on the back wall. An electrical panel presented a problem. It could not move and had to be accessible. Some of the broadband quadratic diffusors were designed into a custom designed rolling cart. This enables them to go over the electrical panel but be legal as they could be moved. This allowed matching the rear sides of the space with broadband diffusion.
GUD high frequency diffusors on side walls and the ceiling over the mix position to enlarge the mix image area back to the client desk. The sound at the client desk is just as linear and only down in level by 3dB from the main mix position. All products were from Real Acoustix LLC. Due to the door location and the “V” in the rear of the room, typical placements for bass traps were negated. We decided to use bass traps within the celling system, a bit unusual but it worked. Overall response is very linear, and only two subtle filters were used to final tune the Rogers LS3 main speakers.
NOTE: Most of the install was done by in house WXXI audio engineers. Andrew Croucher and his team did a spectacular job on this mix suite.
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.
Video: Electronic Acoustics Explained (Understanding how to make One Room Acoustically sound like Any Room)
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.
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.
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’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 in broadcast, 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 45, 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 to meet ADA. If you want high performance doors, you are going to be using double or triple magnetic seal doors and they are not going to meet ADA. Good as they may be acoustically, 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 often 10 dB or more 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 many 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 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, 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 is the tension point for the door, 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 tension is at a latch set, which is where the mag seals come into place. The door is not being pressured to make it work.
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 only 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.
Let’s talk about microphone techniques. I work with a lot of singers. When I work with them, I am always surprised the little they seem to know about how microphones work or that they have a part in getting a successful sound in a live environment.
So, I made a video called Microphones 101 to teach how the new (and not-so-new) microphones work and how to get the best sound in a live venue. *Watch the full video here:
https://www.youtube.com/watch?v=UCFeVznYFNE&t=15s
The first mic we will look at is a kind of beat up Sennheiser wireless. It’s a G1 series wireless with a condenser head. This mic has its own particular group of things that go on with it.
So, this mic has some good and bad characteristics depending on what you’re looking for. When you have no EQ applied to it, you’ll notice there’s some serious sibilance* in this microphone and a fair amount of low frequency handling noise.
DEFINITION: sibilance = a hissing sound
The first thing a singer should be aware of is whether the mic they are using is making noise when they move it around.
And the second thing the need to know is where do they hold the mic when they are singing.
This seems to be a problem for some singers. One of the events that I work at regularly involves 8 singers, all of whom are quite animated on stage. They move around a lot. They do a lot of things and, as a result, the positioning of their microphones is very inconsistent. Microphones are designed to be used at about a two to four inch working distance in front of the capsule. (i.e. their mouths should be no more than 4 inches away from the mic.)
If you take that mic and tilt it, as some people do, to a 90-degree angle, you’ll find that there is a relatively large shift in the response of the mic. Some wind noises change frequency to very low frequencies.
This image shows frequency spectrum where you can see the different frequencies being affected with lows and highs. If you don’t know that, then you are probably not a sound guy, you are probably a singer. The important thing to remember is that the position of the mic is a big deal.
The other thing with the microphone is that gain is related to the position. So, if I hold the mic just 2 inches from my mouth and then I double that working distance, I just went from 2 inches to 4 inches. That movement will cause a huge drop in level, with an attendant change in frequency response. This is what is known as “proximity effect.”
Proximity Effect
Most microphones exhibit proximity effect to some degree, some more than others. Condensers like the 865 head have a lot of proximity. And if you get really close to the capsule, it gets really kind of crazy. Then, if you get extra close to the capsule along with moving it at funny angles, it gets even weirder.
So, when mixing one of the first things we do with condensers is we typically roll off the really low frequencies by putting a low-cut filter on them. And then, once that is done, we start looking at other things as getting rid of sibilance that is on the microphone. Now the singer has a microphone that is a little more neutral, but if they back off the mic, they are gone. In actuality, when the gain drops down to 20 DB below everybody else, it’s a problem.
What I like to do, and not everybody agrees with this, is make it where if they get too far away from the mic, it turns them off. In other words, the gate just turned them off.
Why? Well, when you have 8 singers on stage and you are trying to blend their voices (I deal with this regularly) they are getting so far away from the mic that effectively their voices disappear. You would think that the fact that they no longer hear themselves in the monitors would signal to them that something is wrong. But typically, they ignore it. So, the sound engineer has a singer who is not cognizant of what is going on. At that point, I would rather have their mic off, than having it pick up random noise from other things on stage. It is a matter of preserving the overall good of the audience’ experience.
To recap: working distance is very important and performers need to be aware that, if the working distance is not reasonable, they will not only have tone problems, they will have an, “I left the mix” problem.
Working distance is the first thing to look at. The second is a consistent use of the microphone. One of the more fashionable mic handling styles with some singers, first popularized by rap stars, is cupping the hand over the microphone.
Cupping your hand over a microphone does a number of things.
It changes the frequency response.
It changes the gain.
It changes a lot of things.
As you watch the video, you will notice the big boost around a hundred, two hundred, 1K 2K, and that it gets kind of nasally sounding. Part of that depends on how far you cup your hand. This technique can go from several stages of partial covering till the mic is almost completely covered.
If I wanted to fix these things, I could. If the singer wanted to use the mic the same way all night, I could kick in a compressor to level out the gain problems I’m running into because of all of this. But if that singer suddenly decides to go back to holding the mic normally again, everything changes. Those abrupt changes just do not work well for those of us who care about the overall mix. This is just one example of the problems that happen with singers on stage who inconsistently handle the microphone, not to mention handling noise that also goes on. Add to it that you have eight singers all doing this, you have a lot of unpredictable modifications in the mix.
So avoid the gain changes that occur with microphone working distance. If you are going to be moving around a lot, learn to move your body with your head, which means you cannot have your head going in different directions than your microphone.
Handling a microphone is like playing an instrument.
It is kind of like playing an instrument. If you’re a guitar player, your fingers are supposed to be on the strings when you are playing chords. So you really have to work on this. Many singers seem to, at least the ones I get to work with, ignore all of this. And then they wonder why there are no altos. There are no tenors. There’s no, this there’s no that. The other ones that I really don’t like for other reasons, when I turn this compress around, before I do, this are the ones who eat the microphone.
Now in this particular situation, the gain of the mic is already too high to get away with this. So, I’m clipping the input. Now I’m just backing off that. And then I’m using the compressor and I’ll have to use some makeup gain to get back the gain I’m reducing. But when you get really, really close to one of these microphones, I will have to turn the EQ back on to try to fix the stuff that’s happening by being really, really close to this microphone.
So, there’s a lot that goes on with the 865 p microphone when you get really close to it. So, you end up with a curve that looks pretty bizarre when you get really up there. That sibilance peak, while it’s still there it is less prevalent, and you get all of this low, mid frequency energy going on. The way you fix it is that is you use the mic properly.
So, this is one style of microphone. Let’s talk about one that is radically different. And if you have singers who, for example, like to cup their hands over the mic, is a better choice.
It is a Beyer TCX 58, which is their kind of version of an SM 58. This mic with EQ off is very neutral sounding. Now, if I were to cup my hand over the microphone, there is nowhere near the dramatic effect you get with the condensers, which is one of my contentions. A lot of times people will walk in and they’re used to doing something with the mic they used to use. Then the sound company shows up with a different kind of microphone and hands it to the same artist and they decide to do what they always do. And they don’t realize that they’ve gone from that to this.
And this is now a significant problem. Now you’ll notice also that this Beyer TCX 58 mic, although it has a lot of proximity effect when you get really close to it, it doesn’t have nearly as much. So, the shift with gain is not as hard to manage. If you wanted to work it out with a compressor, you can actually get the compressor to manage the gain a lot better with this microphone.
So you get on this mic and then when you back away from it, it turns you back up. So you can get some things that aren’t nearly as dramatic as you get with proximity effect on a different microphone. The other thing with this one is if you do wanna put in a low cut filter, it solves the low frequency problem pretty much entirely.
Singers => Learn Your Hardware
So, I guess what was trying to get across in this short video is that singers really need to learn their hardware.
They need to learn what works, what doesn’t work. They need to learn how to follow themselves around. And if they’re really singing, dancing type folks, they either have to go to a headset or they have to do something else. But when you’re dealing with handheld microphones, you have a responsibility to make sure you’re rendering properly. And, if you don’t, the sound guy can’t deal with that with eight people.
“Hey, where did I go?“
So wondering why you disappear in the mix is something you shouldn’t be doing, which is why I do this thing where, if you get away too far, in my world I just turn you off. And when you have a bunch of singers on stage and you’re gating them all heavily like that, there is obviously band noise on stage, You have to gate it within that realm to get that to work. But what turning some voices off prevents is picking up a lot of distant noise that you really don’t want in your mix.
So, gating is one good way to solve that problem. And I’ve noticed the singers, at least the ones that I have worked with, they often don’t even know that they left the mix, which shows that they’re really not paying attention …but that’s a whole nother story. And we can talk about that, maybe, some other time.
