Professional Flat Panel Speakers

Frequently Asked Questions (FAQs)

How are Tectonic Plates different from existing speaker designs?

Conventional loudspeakers use uniform pistonic behavior, whether it is a ubiquitous cone or dome; or some form of planar magnetic or electrostatic device; usually a ribbon or an electrostatic driver.  The primary goal of the transducer engineer using a conventional design is to make sure the diaphragm does not have any anomalies, i.e. that it does not “break up” in its pass band. However, diaphragm break up is inevitable. The secondary goal is then to move the frequency of this break up as high as possible so that when it does occur, the cross-over filter has significantly reduced its level.

Tectonic uses a distributed mode loudspeaker (DML) technology which is designed to break up and not just move as a uniform piston.  This break up, i.e. “modal behavior”, is very intentional and highly engineered to produce a “diffuse sound source” which correlates at the human ear.

The acoustic differences, both the traits and the benefits, are also fundamental.  Conventional drivers are either a point-source or a line-source with fixed size radiators, and as such they “beam” (exhibit a narrowing pattern at higher frequencies) and have strong (destructive and constructive) interactions with room boundaries.  DMLs are a diffuse sound source and are highly resistant to disruptive room interactions, especially within the human vocal range, i.e. they are highly intelligible despite bad acoustic spaces.

The bending waves in a DML panel are “dispersive” meaning that the bending wave speed varies with frequency. This ensures that the primary radiation center automatically adjusts its size to provide wide angle output well beyond that of an equivalently sized piston driver.

There are many other benefits from DML applications including high-resistance to microphone feedback, very low distortion, higher relative acoustic efficiencies, low drop-off front to back, a flat-form-factor, and more.

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How do Tectonic DMLs generate the Sound Pressure Levels (SPL) of cone and dome drivers from a rigid panel?

Tectonic DML’s are physically bigger in area than conventional drivers. As an example, the Tectonic DML has approximately 3 times the area of a 12″ driver, therefore the DML’s total movement need only be one third of that to shift the same amount of air.

Imagine a 12-inch bass driver being driven quite hard so that it moves +/- 5mm back and forth. This will produce high SPLs. So we can ask; how much does a DML need to move to shift the same amount of air?

A Bit Deeper –
The radiating area of a 12″ driver is about 0.07m^2. The radiating area of the Tectonic DML is 0.583m x 0.406m = 0.237m^2. If the 12″ driver is moving +/- 5mm, a DML only needs to move +/- 1.5mm to shift the same volume of air. For the DML to produce the same SPL as the 12″ driver it only needs to move 0.07 / 0.237 = 0.3; about a third as much.

However, the surface of a DML does not usually move as a rigid piston and the comparison shown above is only true for low frequency operation of the DML. At higher frequencies the surface of a DML is undergoing complex vibrations with multiple regions moving with different phases, so the total net radiating area is reduced. But remember we are now no longer comparing a DML with a 12” bass driver because a 12″cone cannot radiate above a few hundred Hertz. In the mid-range, a conventional speaker system is likely to use one or two 3” drivers, each having a radiating area of around 0.005m^2. (Compression drivers / horns take over from there.)

Comparing these drivers with the radiating area of a DML (0.237m^2) we can see that this is equivalent to 0.237/0.005 = 52 midrange drivers! So even if not all of the radiating area of a DML is contributing to the on-axis output, there’s easily enough area to provide sufficient output.  

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Why are Tectonic Plates more intelligible than other speaker designs?

Tectonic Plate’s superior intelligibility is a combination of several technical and performance characteristics:

- Tectonic plates generate virtually no 3rd-order harmonic distortion. Pistonic-based transducer designs – cone drivers, compression drivers and horns – by nature of their design – produce odd-order harmonic frequencies (distortion) that are near and can even exceed the amplitude of the original signal source at sound reinforcement output levels.  Odd-order harmonics are both unpleasant sounding and mask intelligibility. Tectonic Plate odd-order harmonic distortion is so far below the original input signal as to be nearly immeasurable.

- The Tectonic DML has a nominal bandwidth of 80Hz – 6kHz. (A large-format ribbon transducer/wave guide takes over from there to above 20kHz.) There are no passive or active cross-over points in the DMLs critical vocal / instrument range that could introduce phase, frequency or delay errors. No external DSP or signal processing is required throughout the pass-band of a DML.

- The random and diffuse acoustic radiation characteristics of Tectonic Plates are minimally interactive with reflective room boundaries, thus secondary acoustic arrival reflections are not a correlated secondary sound source and do not decrease intelligibility by way of echoes or slap-back.

- Tectonic Plates create an extremely wide coverage pattern and very long throw, providing stereo or surround imaging to nearly every location in a given venue for nearly the same audio experience to all areas.

Collectively, these attributes provide a superior level of intelligibility over existing loudspeaker systems.

AES Reprint Improvements in Intelligibility through the Use of Diffuse Acoustic Radiators in Sound Distribution 

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How do Tectonic Plates throw farther than other speakers systems?

For all speakers in rooms there is a measurement called the Critical Distance. This is the point where the level of direct sound equals the level of the reverberant sound in the room.

The more directional a speaker is, the further away from the speaker the critical distance occurs.  The critical distance changes from about 30” (75cm) for an omnidirectional source to over 6.6’ (2m) for a more directional one.

Traditional sound reinforcement speakers have always tried to avoid sending too much energy off to the sides, top and/or bottom of a venue because the waves from these speakers are phase coherent and they create unwanted reflections bouncing off the walls, floor etc., which obscures intelligibility.

House_1

Focusing coverage increases the critical distance, meaning that more of the audience is in a region where the sound falls with the square of distance.  Putting the audience in such a region means that those at the front will experience significantly higher sound levels than those at the rear – this is not ideal.

Line arrays and steerable column loudspeaker systems, by design direct the audio energy only at the audience, as much as possible.   The way that these systems increase throw is by increasing the relative volume of the speaker elements that are aimed at the farthest locations, e.g. the top boxes in a line array are receiving more relative power than the boxes located in the lower part of the “J” array.  This allows similar sound levels reach the front and back audiences.

This is the opposite of how real instruments radiate sound into a room, so the effect is not natural.

Enter the DML:

DMLs have wide directivity and therefore give a much reduced critical distance. This means that after the first 3’ (1m) or so, the drop-off in level is closer to a linear slope. Basically the balance between the direct and reverberant fields is much smoother with an omni-directional source such as a DML.

In other words, as you walk away from a DML you are already almost certainly in the reverberant field (after the first 3’/1m or so) and so will experience a much slower drop off. The initial region (direct sound field) is less intense because the DML is radiating its sound over a wide angle, not ‘firing’ it in a specific direction like a traditional system.

The near omni-directional nature of DMLs would cause significant intelligibility problems if it wasn’t for the fact that DMLs are predominantly diffuse sources. This means that all the energy going into driving the reverberant field is not bouncing around and causing interference. It is actually doing what the sound from real instruments does.

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Are Tectonic Plates easier to operate than other speaker systems?

Absolutely Yes, Kind Of and No

YES – Tectonic plates are extremely forgiving when it comes to room placement and coverage, minimizing room interaction and the need for room acoustic treatment. Installation and rigging needs are significantly less than required for line arrays and trapezoidal flown or ground-stacked enclosures.

The Tectonic Plates’ inherent feedback resistance, full band-width frequency response from 80Hz –  20kHz (including HF ribbon driver) and no complex DSP needs makes for minimal processor requirements. We have found, from extensive use of the Tectonic systems in a wide array of settings, that there is little house EQ needed to accommodate specific venues.

We currently recommend the Symetrix Radius for simple cross-over, limiting and system EQ tasks. That’s all the Tectonic system needs. (Note: The Tectonic system requires our own factory-locked settings for cross-over points and power protection.  By-passing these settings will void the Tectonic Warranty.)

KIND OF – Tectonic Plates are highly resistant to feedback and allow for fairly extreme speaker placements and the flexibility to add open mics in front of the Plates. That having been said, some feedback situations can occur, requiring adjustments in staging and level management.

NO – The Tectonic system is merciless in representing the rest of the signal chain and any problems that may exist that other speaker system do not reveal.  (Verified at several demonstrations in major venues where poor electronics, bad microphones, unknown DSP plug-ins, internal routing errors, word-clock issues etc. were discovered.) Please note: This is not bragging. It is a reality of a low distortion, revealing speaker system.

Furthermore, the traditional cues to the sound operator that the system is being pushed too hard are not generated by the Tectonic Plates. Typical symptoms include excessive 3rd-order harmonic distortion and voice coil bottoming-out. The Tectonic system cannot produce these effects, so the system just goes until it doesn’t.

Pointing an SPL meter at the Tectonic Plates is not an accurate measurement of excessive system output, as the DMLs are not producing a pistonic audio energy wave into the room; ie. not producing ‘Sound Presssure’ that a meter is expecting to measure. SPL meter readings of the Tectonic Plates typically read about 7dB less than actual system output.

We provide processor files for Symetrix, Lake, Rane, etc… system controllers that include limiting parameters to keep excessive system drive from occurring. That having been said, operator orientation is strongly advised.


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MORE INFORMATION

What is the difference between Tectonic Plates and other flat-format speakers systems?

The fundamental difference is that all other flat panel speaker systems use uniform pistonic behavior; usually a ribbon or an electrostatic driver.

The primary goal of the transducer engineer using a conventional design is to make sure the diaphragm does not have any anomalies, i.e. that they do not “break up”.  Tectonic uses a distributed mode loudspeaker (DML) design, which is designed to break up and not move as a uniform piston.  This break up, i.e. “modal behavior”, is very intentional and highly engineered to produce a “diffuse sound source” which correlates at the human ear.

The acoustic differences, both the traits and the benefits, are also fundamental.  Conventional flat panel drivers, including ribbon loudspeakers, are either a point-source or a line-source, and as such they both “beam” (exhibit a narrowing pattern at higher frequencies) and have destructive interactions with room boundaries.

DMLs, again, are a diffuse sound source and do not beam within their intended operating range. The diffuse nature of a DML’s output means they are highly resistant to destructive room interactions.  This is most important within the human vocal range, resulting in the Tectonic Plates being highly intelligible despite bad acoustic spaces.

There are many other benefits from DML applications, besides a flat form factor, including high-resistance to microphone feedback, very low distortion, higher relative acoustic efficiencies, low drop-off front to back, and more.

Flat Panel Examples:

- Electrostatic Loud Speaker (ELS)

An electrostatic loudspeaker (ESL) is a loudspeaker design in which sound is generated by the force exerted on a membrane suspended in an electrostatic field.  This is a highly resistive device, requiring high voltage amplification and the design is inefficient compared to DMLs.

- Ribbons and Planar Magnetics

Planar magnetic transducers typically consist of two main components: a diaphragm with circuit and magnet arrays. The “planar” in planar magnetics refers to the magnetic field that’s distributed in the same plane (parallel) to the diaphragm. Planar magnetic diaphragms are thin and lightweight are suspended in the magnetic fields created by the magnetic arrays.

- Other Flat Panel Systems

There are hybrid systems, in a flat panel configuration, which are not electrostatic, planar-magnetic or DML based.  For example, (-)-Array offers a product that is configured as a flat panel, using conventional drivers and horns. It’s very complex.

(-)-Array (flat panel, conventional mid-high + compression drivers + DSP)

“The (-) uses twelve 8-inch cone drivers with 2.5” voice coils for low-mid frequencies, powered by six power amplifier channels. The mid-high frequency section uses five 1.75” voice coil compression drivers mounted on 1”x 4” constant directivity waveguides. The drivers form an array exactly in the center of the speaker.”  

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How are Tectonic Plates more feedback resistant than traditional speakers systems?

Feedback is reliant on the looping signal encountering itself in a well-defined way. If the waves coming off a speaker (wavefronts) are ‘coherent’ then it is easy for the signal to encounter itself at just the right time to generate feedback. It’s a bit like watching a kid on a swing. You can quite easily work out the best time to push them because the motion is so clearly defined. This is because the cone moves rigidly, as one.

For a DML the wave fronts are not coherent, as different parts of the DML are moving in different directions, so the wave fronts arriving at the mic are not in a simple order. It’s a bit like trying to push 10 kids all swinging at random – it would be pretty hard to work out how to step in and push them all so that they suddenly all swing together in unison.

Usually feedback occurs at a specific frequency that is often the loudest individual frequency in the speaker’s bandwidth.

For a conventional speaker there are usually two loud frequencies; the 1st mode, (or more correctly the zero-th mode), which is the fundamental mass-spring resonance of the system, and possibly the first break-up mode at the upper end of the drive unit’s pass band. Whichever frequency the feedback locks to, it can often be one of these.

The response of a DML is intentionally designed to have as many modes (resonances) as possible, such that any energy prone to a feedback loop to lock into a specific mode is greatly diminished because there are so many of them! The energy is spread across these multiple modes and no single mode is strongly excited into feedback.

A Bit Deeper –
The critical distance to generate feedback is the distance from the source at which the direct sound level equals the reverberant sound level. For more directional speakers this distance is further from the source (speaker). For more Omni-directional speakers this distance is closer to the source. For feedback to occur, the mic should usually be within the critical distance to ensure a strongly correlated feedback path.

DMLs have wide directivity (more omni-directional) dispersion so the critical distance is closer to the DML, therefore the mic can be brought closer to the speaker before feedback ensues. Conventional speakers with narrower directivity push the critical distance further away from the speaker, therefore feedback occurs from much further out.

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Why don’t Tectonic Plates interact with a room like other speaker systems?

Tectonic DMLs propagate audio energy in a fundamentally different way than traditional speaker designs; whether it is a ubiquitous cone or dome or some form of planar magnetic or electrostatic device.

All of the above mentioned designs rely on a uniform pistonic action that delivers an energized column of air into the performance space, with energy and coverage based on driver size and frequency response. The result is relatively high-energy sound waves meeting the boundaries of an enclosed space in a highly correlated manner that reflect directly back in as a correlated wave front that arrives a bit later at the listener’s ear and, depending upon the difference in arrival time, is perceived as an echo or ‘slap-back’.

Each pistonic driver, in its own frequency range, has its own audio energy and coverage characteristics. Reflected audio wave fronts are coherent only for each driver and will be additive or subtractive to the full band-width audio; creating areas of unequal audio energy, phase, and frequency anomalies.

Tectonic DMLs propagate audio energy as a non-pistonic energy source, such that audio energy, while initially pistonic enough to create a stereo image, is predominantly diffuse and random. Audio energy produced by a DML that bounces off of a reflective surface is equally diffuse, random, and therefore non-disruptive. Reflected audio energy is not simply correlated to the source audio, and therefore not perceived as an echo or ‘slap-back’.

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Can Tectonic Plates create a Stereo or Surround image for nearly every seat?

Yes. The panels can produce highly directional sounds, including stereo and surround imaging.  This is true for listeners far off axis, including positions on the outside of a stereo outside panel. There are no sweet spots where a listener needs to sit to hear differential acoustic information coming from the panels to create a stereo image. All seats receive stereo directional cues.

There is a relatively small component of pistonic energy that is produced by a DML, right at the beginning of the panel’s excitation. This gives the ear just the cue it requires to locate the source and, with two speakers, to create a stable stereo or surround image. When the remaining energy arrives it does not conflict with the initial component because the remainder is the diffuse output, containing none of the echoes or interference that a conventional speaker produces.

Additionally, since the panels have little drop off (i.e. long throw) and stable wide coverage, the distance from any given panel does not adversely affect the imaging capability.  This means that a person sitting in the corner of a venue, either in the front or in the back, can hear stereo and surround events.

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Are Tectonic Plates less expensive to own and operate?

The economic advantage for Tectonic Plates is realized in the cost of ownership and use; compact form factor, reduced power and processing needs, minimal room treatment needs, transport and rigging savings, etc.

The Tectonic Plates are designed for sound reinforcement use in mid to larger sized venues (up to approximately 10,000 seats), both fixed install and portable.  They are very high-performance (power, loudness and reliability) and designed to replace traditional line-array solutions for these applications.

In real world comparisons, Tectonic has found that fewer speakers are needed to cover the same space as competitive line arrays.  We also believe that the Tectonic solution does this with superior acoustic performance.

For example, a 5×5 (10 Plates total) system can typically cover an audience up to 7,500 seats or more depending on the configuration of the venue.  This same coverage, employing a line array, may take up to ten boxes per side (20 boxes total), or more.  And this type of venue can require fill speakers to augment the highly directional coverage of a line array.

Another example – for smaller venues – would be a simple 1×1 Tectonic system (one panel on each side of a venue), supported by an appropriate subwoofer configuration. This simple install can support 50 to 500 seats, or more, depending on the configuration of the space, and can be mounted employing floor stands or a simple VESA compatible (flat screen TV) mount.

Compared to large-format line arrays, Tectonic Plates are compact, lightweight, quick and simple to rig. The integral rigging system and wide variety of quick-pin interconnects allows complex hangs to be assembled and raised right out of our ‘Toaster’ four-plate road cases.

Two Tectonic ‘Toaster’ cases containing four Tectonic Plates each can easily cover 3,500 – 5,000 seats.

The electrical impedance of a Tectonic DML is predominantly resistive over almost all of its bandwidth, presenting a much friendlier load to amplifiers than almost any other speaker type; with greatly reduced amp and A.C. power needs. Due to the efficiencies of the Tectonic Plate design, A.C. power and amplifier demands are significantly lower; typically two 110v 20A outlets for 5,000 seats.

Subwoofers, and their power needs, are additional.

Here’s a real world example from a recent mid-sized national tour:
“A five-month tour with Tectonic Plates could have eliminated the need for one semi-truck at a savings of $5,000 per week for the driver & the rig.

This would be well over $100,000 potential savings. A Tectonic system at retail would equal the savings.

It’s zero-sum before even factoring in the reduction in processing, amplifiers, power requirements, rigging and labor; on the very first tour!”  

Tour-Trucks

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