# Gymnatorium Upgrades



## ChasB (Dec 17, 2014)

Hello,

I'm a band director at a small public middle school in Iowa, and am also involved in the technical side of our theatrical productions (fall play and spring musical). Though, I am primarily a musician, I also have a strong background in building speakers and feel very comfortable digging into the workings of our PA.

A month or so ago, my principal came to me with complaints about our PA from the community. He made a presentation to our school board about making upgrades this year, and they have agreed that we do need an upgrade. Unfortunately, they haven't given me a budget to work with yet (I'm going to guestimate under the $15,000 mark, but they may give me more), and I highly doubt any acoustical treatments will be possible since it will still have to function as a gym.

I do have something of a wishlist, but no specific components picked out yet. We are looking to upgrade everything. Right now, we have an archaic 12 channel powered yamaha mixer, a pair of mismatched speakers, and a pair of equally archaic monitors. I'm looking for (at the very least) a 24 channel mixer (unpowered), a power amp, and new speakers. I imagine we don't need a ridiculous amount of power, as the 200-300 watt (RMS) output of our powered mixer is more than enough to fill the space. I would like to build a setup that has a relatively flat frequency response, provides even coverage for the audience (linear array?), and is fairly easy for me to train other staff members. I am not in the least bit afraid to build the speakers, as we have all necessary tools and a maintenance guy that is very helpful.

Any suggestions are greatly appreciated.


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## jkowtko (Dec 17, 2014)

I do sound for a local middle school's music concerts here in California, have been able to get it to sound pretty good with minimal equipment. We have pull out bleachers that seat ~500, and acoustic panel treatments on the other three walls. High vaulted ceiling. The building is ~5 yrs old.

If you have something remotely similar feel free to PM me, send pics and we can compare notes. 

Thanks. John


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## AlexDonkle (Dec 17, 2014)

ChasB said:


> I highly doubt any acoustical treatments will be possible since it will still have to function as a gym.



I'm not understanding this statement, we've added acoustical treatment to a lot of gyms largelybecause they were gyms. One case the reverb was so bad, the basketball players couldn't understand what the coaches were shouting, so we did an analysis and covered the ceiling and some of the walls in acoustical panels. Cheapest and most common arrangement is Tectum acoustical panels mounted on the walls (they are impact resistant, designed to take a lot of abuse), and MBI lapendary banners mounted between the roof perlins (depending on the building structure). Downside is that you'd likely need a contractor to install them, involving a lift, which would get expensive and involving hiring an architect to put together bid documents at most schools. 

My opinion, even with upgraded loudspeakers and other components (most likely bigger speakers mounted on tripods), you'd still be likely to get noise complaints if the acoustics aren't addressed.


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## BillConnerFASTC (Dec 18, 2014)

ChasB said:


> Hello,
> 
> A month or so ago, my principal came to me with complaints about our PA from the community.



It bothers me that educated people blame the sound system when the problem is the room. As one well respected acoustical consultant once said in the midst of planning a very large and expensive gymnatorium - maybe arenatorium - "Mozart in a gym is just offensive."


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## jkowtko (Dec 18, 2014)

Our gym has a cinder block shell, but there are two major forms of acoustical treatment that no doubt help significantly:

* a six foot high 2" thick black pad around the three walls that the bleachers are not on, for student safety
* large (6-8' square) acoustic baffle panels placed around the walls above the padding

The bleachers are on the fourth wall and break up the sound well enough when pulled out from the wall.

And then there are the hundreds of parents, filling the bleachers and sitting and standing around the sides of the room. People make great acoustic baffles 

I place two SRM450 speakers on stands on the gym floor about 8-10' out from the front corners of the bleachers, and a center fill placed just in front of the conductor's podium on a 2 foot high stand. The main speakers are pointing at the center of the back wall of the bleachers.

I've been using this setup for six years now for spring and winter concerts, and it sounds pretty good. I notice no echo and very little reverb ... although I'm sure there is some, but it's very well controlled.


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## rwhealey (Dec 18, 2014)

ChasB said:


> Hello,
> 
> I'm a band director at a small public middle school in Iowa, and am also involved in the technical side of our theatrical productions (fall play and spring musical). Though, I am primarily a musician, I also have a strong background in building speakers and feel very comfortable digging into the workings of our PA.
> 
> A month or so ago, my principal came to me with complaints about our PA from the community. He made a presentation to our school board about making upgrades this year, and they have agreed that we do need an upgrade. Unfortunately, they haven't given me a budget to work with yet (I'm going to guestimate under the $15,000 mark, but they may give me more), and I highly doubt any acoustical treatments will be possible since it will still have to function as a gym.



As others have mentioned there are plenty of options for acoustic treatment for a gym. The two most common are probably Tectum, a hard wood like product that is impact resistant (http://www.tectum.com/project-photos-interior-walls.html) and lapendary banners, which are soft vinyl covered ceiling panels that take a hit from a ball since they hang loosely (http://mbiproducts.com/products/lapendary/). The nicest sound system in a room with poor acoustics will still sound bad. There are thing you can do with a sound system to help avoid poor acoustic problems, but it is usually cheaper and easier to fix the acoustics in the first place.

Depending on the size of your room, I think your $15,00 is a little low for a high quality performance sound system if you don't plan on re-using any parts.


> I do have something of a wishlist, but no specific components picked out yet. We are looking to upgrade everything. Right now, we have an archaic 12 channel powered yamaha mixer, a pair of mismatched speakers, and a pair of equally archaic monitors. I'm looking for (at the very least) a 24 channel mixer (unpowered), a power amp, and new speakers. I imagine we don't need a ridiculous amount of power, as the 200-300 watt (RMS) output of our powered mixer is more than enough to fill the space. I would like to build a setup that has a relatively flat frequency response, provides even coverage for the audience (linear array?), and is fairly easy for me to train other staff members. I am not in the least bit afraid to build the speakers, as we have all necessary tools and a maintenance guy that is very helpful.
> 
> Any suggestions are greatly appreciated.



Your comment about building speakers is a bit of a red flag for a few reasons. You won't be able to build something that can be certified to fly yourself. The cost of having a structural engineer design and a licensed contractor build a cage for non-flying speaker will greatly exceed the cost of buying a speaker designed to fly. Furthermore, despite claims out there on the internet that you are being ripped off by large commercial speaker manufacturers, there is a reason speaker manufacturers charge what they do for their speakers. Even if you manage to design a speaker that sounds better than a pre-made one, which is a tall order, the cost of materials and labor (your time and the maintenance guy's time are valuable) greatly exceeds the cost of buying a commercially available speaker. There are some pros out there who build their own speakers for fun, but unless you are Clair Global you aren't building them for profit.

My advice is that ask for design funds from the school board to bring in a professional. They can work with you on budgeting and system planning and produce design documents you can put out to bid.


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## FMEng (Dec 18, 2014)

I think rwhealey summed it up pretty well. The cost and complexity of building a sound system that will provide adequate intelligibility is proportional to how bad the acoustics are. Gyms and large, traditional churches are among the worst. Without a well engineered design, you stand a good chance of throwing most of your money away without actually making any improvement in people being able to understand the spoken word. Find a consultant to do the design without any interest in selling you an installation. Then hire a contractor to implement the design to the consultant's specifications.

Plan on spending most of your installation budget on acoustical treatment, rigging, speakers, amps, and processing. The "front end" of the system, like mics, mixers, cables, monitor speakers, etc. can always be improved and added to later. None of the "front end" stuff matters if the sound doesn't get from the speaker to the audience or if the reverberation destroys intelligibility.


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## jkowtko (Dec 18, 2014)

I think you guys are overthinking it. Don't hang speakers from a gym ceiling or you'll get nothing but reflections. Place them on stands six feet off the ground and close to the audience, and it will sound fine. Cover them with speaker cover fabric to make them look nice if you like. Aside from very high-end line arrays, I have never heard ceiling mounted speakers that sounded very good. Since your budget isn't $250k, I think $15k will just get you into a lot of trouble. Try spending $2-3k on a club gig setup and I bet you'll be happy with your bang for the buck.


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## lwinters630 (Dec 18, 2014)

I put a sound craft si expression in a gym and some sure sm58. The compression on the sound craft was a major improvement. Added some portable Mackie pointed at the bleachers so I could reduce feedback from the ceiling mains into the mic. It's still a gym now they can understand what is said or sung. 7 - 10k


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## FMEng (Dec 19, 2014)

There is only one way to improve intelligibility: Improve the ratio of direct sound to reflected or reverberant sound. You can do that a few ways.

1. Reduce the reflectivity of surfaces by adding absorption. This is easy to do with high frequencies and hard to do at low frequencies.
2. Increase the directivity of the speakers so less sound hits reflective surfaces. Again, this is hard to do as frequencies get lower.
3. Improve the evenness of coverage across the audience.
4. Get the speakers closer to the listeners.

That last one doesn't work in many situations. The first three take expertise to accomplish.

I disagree that ceiling speakers don't work. It is harder to make them work, because it takes the right type of speaker, the right quantity, put in the right place. (See numbers 2 and 3 above.) Just recently, it is getting easier to put the right speakers in highly reverberant spaces, because the speaker manufacturers are making speakers that can control patterns like nothing that came before. The catch is the right speakers cost more, so contractors install bid winning systems that don't work. Consequently, many examples in school gyms are very poor. Anyone can make loud noise in a space, but it takes an expert to provide intelligible speech.

I'm not an acoustician, so I will stop playing one on TV.


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## Robert (Dec 19, 2014)

I spec'd a small line array system into a gym and had satisfactory results. This was a change from the 4 3-way delayed box speakers someone else suggested. I guess this would fall into the category of directed sound. During rehearsals it is too bright, but as mentioned add about 500 portable sound baffles (people) and you get good coverage and less splatter. No special sound treatment done, though I suggested hanging about 250 sound blankets in the steel work. They were too expensive. We avoided digital sound consoles as no one was there to run it on a continual basis. I did have a the install company put in a DSP and sweep the room. Working very well 6 years later.


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## AlexDonkle (Dec 19, 2014)

jkowtko said:


> I think you guys are overthinking it. Don't hang speakers from a gym ceiling or you'll get nothing but reflections. Place them on stands six feet off the ground and close to the audience, and it will sound fine. Cover them with speaker cover fabric to make them look nice if you like. Aside from very high-end line arrays, I have never heard ceiling mounted speakers that sounded very good. Since your budget isn't $250k, I think $15k will just get you into a lot of trouble. Try spending $2-3k on a club gig setup and I bet you'll be happy with your bang for the buck.



In my experience, if the school principal is actually receiving complaints from the community about the sound, it's almost guaranteed to be an intelligibility problem. New speakers might sound a bit better with more bass, but they don't fix problems like that. Acoustical treatment on the other hand, make any speakers used in the space sound better and clearer to the audience.


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## BillConnerFASTC (Dec 19, 2014)

AlexDonkle said:


> In my experience, if the school principal is actually receiving complaints from the community about the sound, it's almost guaranteed to be an intelligibility problem. New speakers might sound a bit better with more bass, but they don't fix problems like that. Acoustical treatment on the other hand, make any speakers used in the space sound better and clearer to the audience.


I agree. I've observed acoustic consultants demonstrate this to the owner/user group convincingly a number of times. Plenty of volume, just not understandable. Shaping and absorption. Quieting the HVAC is also often an ingredient to improving acoustics. Only a/v contractors seem to think it can be solved with only their gear.


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## ChasB (Dec 19, 2014)

Thanks for all the input! I guess when I was writing the original post, I was so concentrated on treatments for the floor and low hanging baffles from the ceiling that I forgot to take into account wall treatments and other things. I talked to my principal again about some options for acoustic treatments, and we have decided to bring in a consultant from Des Moines. Our space isn't as big as you think it is (it's not even a regulation size basketball court), and on average, we have about 200 people come to our performances. As it sits right now, there aren't any speakers flying in the middle of the gym. Our speakers are wall mounted on either side of the stage.


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## rwhealey (Dec 19, 2014)

jkowtko said:


> I think you guys are overthinking it. Don't hang speakers from a gym ceiling or you'll get nothing but reflections. Place them on stands six feet off the ground and close to the audience, and it will sound fine. Cover them with speaker cover fabric to make them look nice if you like. Aside from very high-end line arrays, I have never heard ceiling mounted speakers that sounded very good. Since your budget isn't $250k, I think $15k will just get you into a lot of trouble. Try spending $2-3k on a club gig setup and I bet you'll be happy with your bang for the buck.



Highly directional speakers flown from the ceiling will allow you to have even coverage and keep the sound off the walls. Speakers on stands six feet in front of the audience are nice for portable situations because they're easy to set up, but are poor from a coverage standpoint because you will be much louder in the front than in the back. Unless you tilt the speakers down, a good portion of the sound will go right over the audience and hit the back wall.

$3k won't even buy you a 24 channel console and a case (http://www.fullcompass.com/product/...ign=googleps&gclid=CI-Qrue50sICFQuQaQod6IQAeg).


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## Timothy A. Samuelson (Dec 20, 2014)

BillConnerASTC said:


> It bothers me that educated people blame the sound system when the problem is the room. As one well respected acoustical consultant once said in the midst of planning a very large and expensive gymnatorium - maybe arenatorium - "Mozart in a gym is just offensive."


THANK YOU!!!

I have gotten non-stop complaints about the sound system. We're running a PM5-D with Community speakers. Yeah, I've got some bad cables that sometimes get used unintentionally, but the system is incredible. It's the carpet, cloth seats, millions of wall panels, and ceiling clouds that are making the space so muffled. (I should mention that our "theater" was originally a mega-church. I still have a working baptistry)


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## teqniqal (Dec 21, 2014)

Another reason to bring-in an experienced acoustics and sound system design consultant is that the two systems have to work together. Finding a functional and budgetary balance between HVAC noise reduction, room acoustics, and new sound equipment is a delicate balancing act. All the acoustical treatments and sound systems in the world won't help if the HVAC is too noisy and drowns-out the subtleties and nuances of the performer's voices and/or instruments; and acoustical treatments must find a balance between absorption and diffusion so that the performers can have a sense of their own presence in the space (overly dead rooms are difficult to perform in). Reducing the noise floor of the room is also vital to achieving useable recordings - microphones don't discriminate between voices, instruments and HVAC noise.

Theatre imposes different operational requirements on a sound system than does making general announcements for a sports event or playing in a rock band, so hiring someone that 'gets' theatre can go a long way towards having a theatre-friendly sound system. 

In a theatre or music setting, particularly with inexperienced performers and sound operators, it always seems that the sound system is run right on the ragged edge of going into feedback, so you might see if you can get a demonstration of the Tectonic Audio Labs PL-12 speakers. They work well in spaces that don't have optimum acoustics, and their resistance to feedback is amazing. This allows you to place the speakers down low, flanking the performance area, and further create the acoustic illusion that the sound is coming from the performers and not from a disembodied source as when the reinforced sound is coming from above the performance area.

Being afraid of using a digital sound mixing console can further impede your success at presenting good quality audio to the audience. Digital mixers that allow you to individually adjust the signal delay of each microphone can add presence to the performance when the microphones that are upstage of the speakers are adjusted to deliver sound to the speaker system in-sync with the sound emanating from the source.  This reduces the 'hollowness' frequently heard in many presentations. These features, like any other aspect of a mixer, can be ignored or misused by the operator, so settling for mediocre sound just to meet the least skilled operator's needs is a recipe for a lack-luster presentation.


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## FMEng (Dec 21, 2014)

teqniqal said:


> so you might see if you can get a demonstration of the Tectonic Audio Labs PL-12 speakers. They work well in spaces that don't have optimum acoustics, and their resistance to feedback is amazing.



I get very nervous when I see speaker manufacturers making claims that defy physics. It's one thing to claim they have a flat panel speaker that exhibits wide dispersion and linear reproduction. It sounds like snake oil when they make claims like the speaker "has very little interaction with the room." We know that wide, uncontrolled dispersion is the worst possible thing in a highly reverberant space, yet they seem to claim otherwise. Sorry, I'll wait until reputable acoustical engineers start employing these things with documented results.


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## jkowtko (Dec 22, 2014)

Here are some photos of our gym setup, showing the black wall padding and the high mounted acoustic panels. Sorry these are not great photots ... I didn't take any myself and had to ask the videographer to grab a couple of frames from some of his footage (which focuses entirely on the musicians and not the sound setup .

You can see my center fill -- Anchor AN-1000x on a small homemade stand. On the leftside image you can also see another Anchor speaker as piano monitor for the choir.

What you cannot see, unfortunately, are my mains ... Mackie SRM450s mounted on tripod stands. They are positioned on the same line as the center speaker, even with the sides of the bleachers.

What you also cannot see is the vaulted ceiling (dome roof). I don't remember if the ceiling has acoustic treatment or not.


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## Builtkarr (May 26, 2016)

FMEng said:


> I get very nervous when I see speaker manufacturers making claims that defy physics. It's one thing to claim they have a flat panel speaker that exhibits wide dispersion and linear reproduction. It sounds like snake oil when they make claims like the speaker "has very little interaction with the room." We know that wide, uncontrolled dispersion is the worst possible thing in a highly reverberant space, yet they seem to claim otherwise. Sorry, I'll wait until reputable acoustical engineers start employing these things with documented results.



So, I'm currently the TD of a high school theater program and in the process to transition to a new high school theater as TD. Before my start date at new theater the current theater chair has lined up a demo with Tectonic Audio Labs to show off their flat speaker panel due to sound issues in their space that I will be present for. The FOH speakers are hanging from the ceiling at the proscenium upstage of the stage extension. Obviously this is the reason for the problematic sound issues as when the stage extension is in, the action is being played downstage of the speakers with body or handheld mics causing feedback. 

I've looked at Tectonic's website. http://www.tectonicaudiolabs.com I have watched a number of their informational videos and read some of their articles and it looks pretty amazing how they can reduce / cancel feedback. So obviously if this new high school has the money and can invest in this speaker system I'm all for it. Sound is my weakest discipline and if these speakers work the way they claim to it will save me a serious headache while I'm trying to learn new ropes as well as equipment all while keeping the season going from a technical standpoint without constantly fighting feedback.

I've searched for "tectonic", "DML" and this is the only thread that came up. So I wanted to see if we could expand the thread a bit on this topic. I'm wondering two things. 

1. Are there any of you out there who have witnessed demo's of these speakers or who have them in systems you currently work in or have worked in? If so, are they as good as they claim to be? FMEng is skeptical... Is there a negative side to going with these speakers that may not be well known?  For the demo I will be a witness to are there any specific questions I should be asking, or specific situations I should ask the tectonic people to put their speakers in to see results? Keep in mind I have not worked in this venue yet, just toured it and saw a small band perform for a few minutes.

2. It seems to me that moving the existing speakers downstage to the front of the stage extension should solve the feedback problem and in theory should be way cheaper than going with an entirely new system. Getting new stuff is great, especially in high school which is typically drastically underfunded and of course I'll take them if they tell me we are going that way, but just saying....

Any feedback would be appreciated.


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## ChasB (May 26, 2016)

If anybody's wondering how this turned out... Basically, I told the supt. of the district that there needed to be some sort of treatment in the space, and she told me I didn't know what I was talking about. Then she proceeded to instruct the board to go with the cheapest bid we received because "we don't need any soundproofing". The good news is that I work at a different school district now that actually values my input.


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## FMEng (May 27, 2016)

The Techtonics have been around a couple of years now. The marketing still has wonderous claims based entirely on anecdotal observations, and ancedotal observations of sound are highly suggestible and mostly worthless. (I've got speaker cable with molecule aligned copper, that was smelted by monks, with hand woven cloth insulation, coated in green marking pen ink for on sale for just $100 a foot.) I have yet to see any measured data of how Techtonic speakers actually perform and one of the company's claims is that they can't be measured. Isn't that convenient? And, I have yet to see them specified in a design by a reputable acoustical engineer. If they lived up to the claims made for them, they'd be the darlings of the industry.

We'd all love to be believers because our audio troubles would be over, hallelujah! But, where are the specifications and measurements? Where are the double-blind intelligibility tests? Where are the Audio Engineering Society papers that explain how and why they work? Where is the PROOF? If they really have something radically new under the sun, they need to demonstrate it through scientific methods.

An A/B test with speakers can easily be skewed with nothing more than small, correctable, frequency response variations and a 1 or 2 dB difference in level, and intelligibility is highly subjective. My advice is hire a competent consultant to engineer a proper system for your new space.


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## teqniqal (Jun 1, 2016)

Builtkarr said:


> ... it looks pretty amazing how they can reduce / cancel feedback. So obviously if this new high school has the money and can invest in this speaker system I'm all for it. Sound is my weakest discipline and if these speakers work the way they claim to it will save me a serious headache while I'm trying to learn new ropes as well as equipment all while keeping the season going from a technical standpoint without constantly fighting feedback.
> 
> 1. Are there any of you out there who have witnessed demo's of these speakers or who have them in systems you currently work in or have worked in? If so, are they as good as they claim to be? FMEng is skeptical... Is there a negative side to going with these speakers that may not be well known? For the demo I will be a witness to are there any specific questions I should be asking, or specific situations I should ask the tectonic people to put their speakers in to see results? Keep in mind I have not worked in this venue yet, just toured it and saw a small band perform for a few minutes.
> 
> 2. It seems to me that moving the existing speakers downstage to the front of the stage extension should solve the feedback problem and in theory should be way cheaper than going with an entirely new system. Getting new stuff is great, especially in high school which is typically drastically underfunded and of course I'll take them if they tell me we are going that way, but just saying....


To clarify, the DML speakers don't reduce or cancel feedback. What they do is _reduce the likelihood of feedback_ because there are not single point-source relationships between the speakers and the microphones in the same way that cones or horns do. The sound 'comes from everywhere' across the face of the DML driver panel which is different than what happens with a conventional loudspeaker. The other contributing factor to their feedback resistance is that they don't have a cross-over in the middle of the vocal band. The DML bandwidth is about 160 Hz up to well above 6-8KHz. Crossovers introduce phase shifts, which create frequencies where the mic and speaker are perfectly in-phase and facilitate a regenerative cycle. You can make a DML speaker feedback, it is just more difficult to do so. This can give that extra 'margin of error' for inexperienced operators in challenging rooms.

In response to Question #1: I have heard the Tectonic speakers in five different types of rooms (Black box theatre, Large movie-theatre renovated into a performance hall, Classic 1920's style multi-balconied theatre, a modern sheetrock-on-metal-studs auditorium, and in modern sheetrock-on-metal-studs church with little diffusion). In each instance the sound was clear and easy to understand, even when the venues were lightly occupied and there was little absorption due to human presence.

Questions to ask during the demo: This is more about getting a demo that matches your typical presentation situation than it is about sitting in a classroom and studying physics. If you have poor mics, don't expect a DML, or any new speaker, to help change the situation. Plan on acquiring good new mics for your new sound system, and maybe rent a few for your demo. This way you don't blame the speakers for the mic's problems (true for any speaker demo). I have witnessed DML demos where the owner insisted on using a bad mic and/or wireless transmitter / receiver and then they complained that the speakers sounded bad. The mic was replaced and the DMLs sounded fine. The same is true for mixing consoles (yes, even the electronics of some consoles funk-up the sound), and particularly mixing consoles with digital plug-ins (one demo had a plug-in active that really made the sound awful, and once removed from the system, sound was good). Don't plan on bringing your media player with a bunch of crappy MP3 files and expect to hear a difference. Bring original recordings from your shows, or better yet, bring in real live actors, singers, musical instruments (acoustic types, not distortion based electronic types), and lecturers to speak / sing / play into the system and listen to how it sounds in the furthest most seats. It is easy to get the middle seats to sound good for most speaker demos, but it is the people in the back that suffer because they are hearing the most diffuse sound from the speakers interacting with the room reflections. Yes, more directional horn-type speakers will help to 'punch' the sound to the back of a room, but they do so at the expense of the sound quality (the 'honking' of horns becomes very apparent once you have experienced the non-horn DML approach to sound reproduction). Playing-back prerecorded sound tracks is not a good way to demo any speaker. Listen to how live sound 'sounds' in the typical audience members seat.

Good room acoustics will always help, however, solving room acoustics problems is not always part of a sound system upgrade initiative. The interesting thing about the way the sound waves that emanate from a DML speaker is that it interacts with the room surfaces in a much less intense way. A good analogy would be to differentiate between the way a soft light source like a 2'x2' studio wash light with a diffussor panel in front of them would shine light on a wall and it bounces off of it, vs. how a ellipsoidal spotlight shines light (like a horn) with a very hard edge cut-off. Both lights can bounce off of the wall and provide a specified illumination level at the seats, but you tend to see (hear) the glare (harsh honk) from the ellipsoidal (horn) more noticeably coming off the wall. The best example of this I heard was in a deep (~100' from stage to rear seating row) room with hard plaster walls. You would normally hear a lot of sound contribution from the wall reflections from a horn type speaker, but with the DML's this was inconsequential and the sound was still clear. Traditionally, in a room this deep, a sound system designer might have placed a row of delay speaker about mid-way back so they could keep the back of the room levels up while not pushing the sound levels from the main speakers up into feed-back. This was not necessary with DML's.

Although some have derided the DML speakers of 'having no proof' or just being 'snake oil', they usually have not actually heard the speakers in a real room with a real sound source. Armchair speaker experts can speak loudly about that which they know little, but if they would take the time to A.) Read the numerous truly scientific papers posted on the Tectonic web site, B.) actually listen to the speakers in a demo or actual installation, and C.) learn how to spell 'Tectonic', it might bring some credibility to their arguments. Sadly, since the introduction of computerized modelling of sound systems with programs like EASE, fewer and fewer people actually listen to speakers to make expensive decisions. The reality is that programs like EASE are written to simulate the effects of point source sound devices, not DML's. It is not currently possible to simulate the acoustic response of a DML in a room with EASE. it doesn't make EASE a useless tool for modelling point source loudspeakers, but it is applying the wrong tool to the job. It is interesting that many of those that critique the DML's without hearing them are followers of the 'Don Davis School of Sound System Design' where everything is based upon the Q of a speaker. If you go back and reread the Davis' books and Pat Brown's explanations about Q and intelligibility, it actually reinforces the fact that a DML speaker can provide good intelligibility.

Wide coverage angle is not necessarily a bad thing. In the Don Davis School of Q, we are taught to narrow the speaker coverage angles so that the sound only falls on the seats and nowhere else. This makes designing conventional speaker arrays that laterally cover a room well enough to create a good stereo image very difficult, so what you actually end-up with is the left half of the room hearing the left speaker array, and the right half of the room hearing the right speaker array. This does not provide a good listener experience for a majority of the audience. DML's can be cross-fired in a room to provide this coverage with little ill effect in regard to the feedback rejection (one of the reasons conventional speaker arrays are pushed so far forward of the stage is to try to keep the speaker spill off the stage and causing feedback).

This is also true on the vertical axis. Typically speakers are mounted up high and the coverage pattern is aimed down so as to get even coverage across the seating. This results in a mental disconnect between where the performers are located and where the sound appears to come from. DML speakers can be set-up down close to the same elevation as the performers so the sound appears to emanate from the same elevation as the source, and yet not compromise coverage of the audience nor feedback stability.

Also of note is that the Don Davis School of Q equations say you should have poor feedback resistance with low Q wide angle speakers, however, the Tectonic DML's clearly show amazing feedback resistance. If these equations are wrong, then how else are they wrong when it comes to applying them to sound system design with DML's? Just because you can't fully explain something that work really well, doesn't make it wrong or bogus, it just means that the mathematics and computational simulation software hasn't yet caught-up to the reality.
If you are insistent that "Q" is the most important aspect to reduce feedback, then you have to explain how an almost hemispheric coverage 'low-Q' loudspeaker can be so feed-back resistant, as this goes against all of the Don Davis 'standard' sound system equations. You can't say your equations explain everything and get this result.
If you are insistent that "Q" is the most important aspect to reduce feedback, then you have to explain how an almost hemispheric coverage 'low-Q' loudspeaker can be so feed-back resistant, as this goes against all of the Don Davis 'standard' sound system equations. You can't say your equations explain everything and get this result.
If you are insistent that "Q" is the most important aspect to reduce feedback, then you have to explain how an almost hemispheric coverage 'low-Q' loudspeaker can be so feed-back resistant, as this goes against all of the Don Davis 'standard' sound system equations. You can't say your equations explain everything and get this result.

As mentioned before, the Tectonic DML has no cross-over in the middle of the vocal range (or like some conventional horn-and-cone boxes, that may have more than one crossover point in that critical range), so the vocals and instruments that have dominant spectral output in this range between 160-8,000 Hz are not 'buggered-up' by sound coming from disparate drivers and skewed in time through the crossover filters. The other unique attribute of DML speakers is that they create very little 3rd harmonic (odd order) distortion. This lack of distortion provides clarity usually masked by conventional drivers. When you get to mix sound through DML speakers you have to start from scratch and unlearn may bad habits that you have acquired over your years of experience because many of the 'tweaks' that you are accustomed to placing on a mix are really just crutches to overcome the distortion you have been hearing from traditional speakers.

The poster said "Getting new stuff is great, especially in high school which is typically drastically underfunded". Regardless of what technology you end-up with, you have to continually remind the administration that "they only get one change to make a good first impression". Each class, each game, each lecture, each and every presentation is a "first impression". If you lose your audience (be they other community members, staff, parents, or students), then the rest of the presentation is pointless. They have to be able to hear without straining to hear. Don't skimp on speakers, mics, or signal processors to keep the system clear and free of distortion and feedback.


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## FMEng (Jun 1, 2016)

You really don't need to repeat yourself over and over. It's rather bold to claim that the 75 years of physics and acoustical engineering must be wrong without any proof. Thank you for making my point. Maybe it's all true and the product is what it claims to be. I am completely serious when I say I'd love to believe everything because we all have places where the supposed attributes would be very useful. But, I don't think it is asking too much for Tectonic to help the science along. Maybe Tectonic should drive that demo van over to Kirkegaard, or one of the better AE schools, and let them start studying the things. The company seems to be afraid of scrutiny.

I stand corrected on one point. There is a handful of 15 year old AES papers written about theoretical DML speakers or lab prototypes, not the product in real world installations. They don't show us if the Tectonic speakers behave similarly to theoretical DMLs or just share the name.

Here is the abstract from an AES paper cited on the Tectonic website:

Acoustic feedback stability is a fundamental limitation of all public address, sound reinforcement and duplex teleconferencing systems. Over the past 30 years, a number of techniques have been developed to help improve the gain before feedback margin. This paper reviews progress to date and demonstrates that a new class of loudspeaker, the distributed mode loudspeaker inherently possesses a number of characteristics which potentially make it less prone to feedback. Initial experiments are reported which show a 4dB improvement in feedback margin without electronic assistance, gains comparable with most other current signal processing techniques.

A 4 dB improvement is not insignificant but it isn't overwhelming. Tectonic's marketing would have us believe its 10-20 dB. Moving the mic a few inches closer to the source achieves the same result.

I took the time, and spent the money, to read a couple of the AES papers a few years ago. As I vaguely recall, one of them lacked any scientific rigor and the other didn't really support Tectonic's claims.


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## teqniqal (Jun 2, 2016)

Just like an acoustically sealed room, a closed mind lets no information in. Apparently, you have read all 26 AES papers (quite a 'handful'), 5 white papers, and watched all 60 of the informational videos on their site (_or maybe not . . ._), and didn't allow any of it to inform your opinion. I guess the differential equations and in-depth research into understanding and defining the devices wasn't rigorous enough for you. How did you ever survive digesting Richard Heyser's papers about the derivation and development of the Heyser transform without thinking it was too simple? Was that not rigorous enough, either? Similar subject, same math, both in the AES library, both showing the world something new. Just because much of the research and authorship has occurred in Europe, Canada, or Japan by persons at universities or companies you may not be familiar with, does not invalidate the quality of the research or insight gained.

No, they are not saying 75 years of physics is wrong, neither did Heyser, it is that some people have chosen to misinterpret the information or have not completely utilized the math. It's taken a 100 years to figure-out what an atom looks like, too, but that doesn't make the physics wrong, it is just that our understanding of it has evolved, and each steps brings us to a clearer understanding about how the world really works. If you will re-read the AES paper about modeling the DML you will see that the DML computer model works for the point-source horns and cones speaker, too, but the opposite is not true. Just like Newtonian Physics don't apply when Quantum Physics does. Yet it is the point-source model that is used by programs like EASE for sound system modelling. Better math is available, but some chose to ignore it. You want to know why they have not released more information about the speakers? It is probably because they know it will be processed through invalid software models. Good information in, bad processing, bad information out. As soon as better modeling software is publicly available, then it makes sense to share data that won't be abused or misrepresented.

No, they have not claimed that there is a 10-20 dB gain-before-feedback improvement (where did you get that?). If you will re-watch the video of the guy shoving the microphone in front of the DML, you will see and hear something that would not likely be possible without extreme feedback if done with with a conventional cone and horn loudspeaker. The 4-dB figure you cite came from math that was based upon point-source modelling. The numbers might be different if recalculated with a DML model, and I would suspect they would be better, as the real-world demonstrations seem to indicate. This reduced feedback feature is highly beneficial for those of us that have to deal with performers that are not fully blessed with a loud voice and proper microphone skills (try telling an experienced lecturer or singer to move closer to the mic and see what that gets you . . .). Rather than foul-up a good signal with auto-tuning phase shifting notch filters, why not use a speaker that does not require that the signal be mangled to be audible? Rather than paying for auto-tuning phase shifting notch filters, why not utilize the funds for a speaker that does not need this processing?

Contrary to your opinion, Tectonic Audio Labs has helped the science along - the DML's they manufacture today far exceed the capabilities of the devices developed, tested, and written about 15 years ago, and the papers and information published since then (and generously compiled for access on their web site - nothing to hide) have demonstrated that, as do the audible performance of their products. If you would go and listen to to the speakers you might even hear what they are talking about. You live less than an hour drive from their office. Have you even made the effort to get an appointment and go visit with them, ask some questions, and hear their devices? Have you gone to one of their nearby installations and listened to a live performance? I have. I have traveled half-way across the country four times to hear and learn about their technology. It is what you do when something is interesting, new, and potentially useful to your craft and trade. Is this the only speaker I listen to, use, specify? No. It is a tool in the tool box. We have to use all of them to stay ahead of the curve. To use any of them, you must understand them the best you can, know their benefits and their limitations, and "Choose wisely, Grasshopper".


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## MNicolai (Jun 10, 2016)

FWIW, I heard the Tectonic speakers on the floor of InfoComm today. Doing a private demo tomorrow but everyone I told in my company to check these out was blown away by what we heard from a previously no-name company to us. 

I'll elaborate more when I know more, but as skeptical as I was I'm much more confident having heard them at medium volume. I'd usually be more reluctant to say that but it seems Tectonic has the support of some of the most key players in our industry. 

Price point is higher than average for a gym system, but I'm optimistic it would be an appropriate long term investment (~15yrs?).


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## MNicolai (Jun 12, 2016)

First of all, I want to point out how kind and accommodating Denny, Erin, Dave, and the whole Tectonic team were to us. Off-site demo rooms during InfoComm can be very inconvenient because of the time it takes to get to the off-site, and then the usual 45min of marketing stump speech that comes before listening to any speakers. They were very accommodating and respectful of our time. It was the ideal demo that many manufacturers fail to provide.

Everyone from our team was impressed at what they heard. The speakers provided very articulate and intelligible sound, and as Tectonic's Dave Krocker put it, "We can shove a snare drums right up your nose and not fatigue your ears."

They had an Astro Spatial Audio rig set up too and ran a demo with a full surround mix that was incredibly dynamic and crystal clear, with full depth of frequency and amplitude. This was one of the most interesting and compelling moments for myself and a few of my colleagues over the course of this year's InfoComm show. As someone who does a lot of projects including electronic acoustic enhancement systems, the pairing of the Tectonic speakers with the Astro Spatial Audio processor was an absolute immersive delight.

The demo room itself was surrounded by velour, like every other demo room at InfoComm. This made it easy to compare it to the other demo rooms that week but difficult to verify the claims Tectonic makes. I'm working on arranging a demo rig be sent to our shop in September so we can find an acoustically challenging room to put these to a real-world test in. 

One of my colleagues thought that the claims made sounded impressive, but like snake oil. He followed up with Ron Sauro of NWAA Labs, a former NASA scientist who does testing on loudspeakers and acoustic materials at a special facility he purchased from NASA. Ron's comments as someone who has done measurements on these speakers, in summary, "It's not voodoo, it's physics!"

My primary concern for this technology is price. The smaller PL11 retails for $7500, and the larger PL12 retails for $10,000. In many cases, I expect an mostly-equivalent point source solution combined with acoustic treatments can be found for less. The saving grace is that because of the high efficiency, you pay less for copper wiring and amplification. Because of form factor, weight, and VESA mounting, you also pay less for custom rigging, blocking, and structure.

Overall, I'd say we were all impressed by what we heard. We still want to do more testing and Tectonic is on-board to give us product to play around with. For the time being, I remain curious, cautious, and optimistic.


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## Builtkarr (Jul 15, 2016)

Well an update of our demo with Tectonic for those of you that are sitting on the edge of your seat waiting for it. They were 2 hrs late, did the demo, we had kids available in wireless lavs to sing in order to test the speakers and there was a good amount of feedback. One of the techs said we couldn't have mics directly in front of the speakers or they would feedback. However the videos on their website with the guy on an sm58 speaking into the mic while right next to the speaker with no feedback seem to sell a different alternative... obviously there is a difference in mics, but still.

So after the demo I asked number of questions. Conversation is paraphrased.

Q: Was this a typical demo? 
A: No
Q: What would you do normally?
A: We'd have time to set up, ring out the room, tune our speakers to the room, adjust them, etc..
Q: What was the reason keeping this from being a typical demo?
A: Time restrictions.
Q: Is this a difficult room for sound from your experience?
A: Not really, we've set up our speakers in a number of different rooms. If you head down to (....can't remember the name of the place.....) and see the set up we did there and listen to the speakers it sounds great and....(I stopped listening.)

So just a recap as to what I took away from this demo. *this is my opinion and based on what I experienced*
-The speakers are not feedback free speakers
-in this instance, it was admitted the demo was not what they usually give, and the reason being was they didn't have enough time. They were 2hrs late...
-I'm supposed to take the techs word that the speakers once tuned to the room, hung just so, and rung out, etc will make this a feedback free room or very close to it. When the demo I just received says otherwise. I hope the speakers do work the way they say they do because that would mean difficult sounding rooms have an easy fix to them, however I will not be purchasing them for this theater because I'm not willing to take that leap of faith. First impressions mean a lot and this 1st impression did not jive with what is sold as what the product does. So onto the next possibility.


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## Builtkarr (Jul 15, 2016)

MNicolai said:


> First of all, I want to point out how kind and accommodating Denny, Erin, Dave, and the whole Tectonic team were to us. Off-site demo rooms during InfoComm can be very inconvenient because of the time it takes to get to the off-site, and then the usual 45min of marketing stump speech that comes before listening to any speakers. They were very accommodating and respectful of our time. It was the ideal demo that many manufacturers fail to provide.
> 
> Everyone from our team was impressed at what they heard. The speakers provided very articulate and intelligible sound, and as Tectonic's Dave Krocker put it, "We can shove a snare drums right up your nose and not fatigue your ears."
> 
> ...


Please post your evaluation of real world tests of these speakers. I'm curious to read your opinion.


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## jkowtko (Jul 15, 2016)

These aren't just repackaged Magneplanar's, are they?

McIntosh also has some flat panel speakers on demo at the local Best Buy / Magnolia shop.

This gimmicky stuff might work well for a lecture hall, but I wouldn't trust something like this when I have to put out some *real* sound ... I'd wait to see if the technology becomes more widely accepted. 

I remember in college our house bought a bunch of $3 60-watt light bulbs that were supposed to be energy efficient and last 10x the 4-for-$0.88 ones ... they didn't. But we spent a lot of money finding that out


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## teqniqal (Jul 15, 2016)

jkowtko said:


> These aren't just repackaged Magneplanar's, are they?
> 
> McIntosh also has some flat panel speakers on demo at the local Best Buy / Magnolia shop.
> 
> This gimmicky stuff might work well for a lecture hall, but I wouldn't trust something like this when I have to put out some *real* sound ... I'd wait to see if the technology becomes more widely accepted.



NO, these are not repackaged Magnaplaners or McIntosh speakers. These are high powered Distributed Mode Loudspeakers (DML's). This is a different way of creating a sound field from the typical pistonic motion of a cone type loudspeaker. It is not an electro-static speaker. It is not a plasma speaker. It is not a ribbon speaker (although they do augment the high frequencies above 6-8KHz with some high power ribbon drivers - the main part of the sound, from about 200 Hz up to 6-8KHz, is emenated from a DML panel.).

'Different Technology' - yes, 'gimmicky' - no. I've heard a pair of these fill an 800 seat auditorium with seats as far as 100' from the stage with great volume and clarity (*real* sound, whatever that is), so a small lecture hall would be no problem at all. Wait if you want, progress waits for no one.


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## jkowtko (Jul 15, 2016)

I think most people wait for price 

This sounds like the audio answer to LED lighting ... but maybe the technology needs to mature a bit more and come down in price.


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