Meyer Sound : Patents

THE STORY

Welcome to our “Gallery of Patents.” From its beginning, Meyer Sound has been known as a leading innovator in performance audio products. Our list of industry firsts includes trapezoidal cabinets, dedicated loudspeaker processors, self-powered loudspeakers, source independent measurement, parabolic long-throw transducers, cardioid subwoofers, the REM manifold, Internet-enabled acoustical prediction, and more.

The technology underlying such innovations can be traced through the course of our patent history. Patents have played an important role at Meyer Sound since the company was established in 1979. Our first U.S. patent (4,152,552) was granted within weeks of the time we opened for business, and has served as a technological foundation for product development ever since.

To be valid, any claim for an intellectual (technically, “utility”) patent must mark a departure in thinking from what is generally accepted and known in the trade. But you don't have to actually make a functional device - or make anything at all, for that matter - in order to patent your idea.

At Meyer Sound, however, all our patents have been incorporated into products in some way, with tangible benefits for the professional audio community. In one sense, we use the patenting process as a framework to transform fledgling concepts into effective products. Seeking a patent disciplines our engineering team by making us more careful and thorough in our work.

Although Meyer Sound’s patent history includes several milestones in audio engineering, it doesn't tell the whole story. We haven’t sought patents on all of our new ideas. Instead we have focused our patent applications on those key concepts that define our distinctive approach to sound reproduction technology.

ABOUT PATENTS

Most patents are utility patents. Design patents are not as well known, and the difference between the two often not understood, so let us explain a little.

A utility patent protects the functional aspects of an invention, while a design patent protects the decorative, or, in patent office terms, the “ornamental” aspects of an invention.

A design patent functions much like a trademark on a product name or company logo. Less familiar to most people than the utility patent, a design patent is granted for distinctive outward appearance, independent of how the product functions.

The purpose of a design patent is to prevent confusion in the minds of consumers. A familiar example would be the counterfeit "ROLLEX" watches sometimes sold on city street corners. Although the name on the watch face may have an extra “L” in it (therefore making it not identical in appearance to the real thing), the overall design nevertheless confuses the public and clearly violates any design patent held by Rolex.

Horn Speaker and Method for Producing Low Distortion Sound
US Patent:	4,152,552
Date Filed:	January 23, 1978
Date Issued:	May 1, 1979
Inventors:	John D. Meyer
The company's first patent was the result of John Meyer's pioneering research into sources of non-linearity in compression drivers. Much of this work was done during the 1970s, when Meyer was director of the Acoustics Laboratory at the Institute for Advanced Musical Studies in Switzerland. The patent describes a method for reducing distortion by a factor of ten, and was first applied to horns in the UM-1 (1979) and UPA-1 (1980). Read More

Loudspeaker (UPA-1 Trapezoidal Cabinet)
US Patent:	D271,967
Date Filed:	May 27, 1981
Date Issued:	December 27, 1983
Inventors:	John Meyer, Alexander Yuill-Thornton II
The UPA-1 marked a revolution in the design of small, high-powered sound reinforcement systems. In addition to being the first professional loudspeaker with dedicated control electronics, it introduced the industry to arrayable, trapezoidal loudspeaker cabinets. The trapezoidal shape of the cabinet is the subject of this design patent. A trapezoidal shape facilitates precise configuration of horizontal loudspeaker arrays into a sound source that emulates the radiation characteristics (in the horizontal plane) of a point source.

Loudspeaker Enclosure (833 Studio Monitor)
US Patent:	D282,255
Date Filed:	September 16, 1982
Date Issued:	January 21, 1986
Inventors:	Robert Ross
The 833 Studio Reference Monitor system was the next step in studio monitors after the ACD monitor Meyer Sound made in the company's earliest days. The 833 utilized dedicated control electronics and advanced horn design to achieve an extremely wide dynamic range, low distortion and controlled directivity. This patent is a design patent on the shape of the 833 cabinet.

Circuit and Method for Correcting Distortion in a Digital Audio System (Anti-Aliasing Filter)
US Patent:	4,764,938
Date Filed:	October 25, 1982
Date Issued:	August 16, 1988
Inventors:	John D. Meyer
Many early digital recording systems, notably the Sony PCM-F1, used high-order "brick wall" filters to prevent aliasing. Unfortunately, these filters introduced delay that varied with frequency, resulting in considerable phase distortion. This patent introduced a circuit to correct these phase anomalies and obtain a relatively constant group delay. The underlying technology behind the patent emerged from Meyer Sound's ongoing research into advanced phase correction circuits for what would become the HD-1 high-definition audio monitor. Read More

Ohmically Isolated Input Circuit
US Patent:	4,779,058
Date Filed:	July 25, 1986
Date Issued:	October 18, 1988
Inventors:	John D. Meyer
Analog audio inputs and outputs using three-pin XLR connectors have long suffered from inconsistency between manufacturers in both wiring of connectors and in input and output circuitry. As a result, miswiring has been a constant problem that creates gain problems, AC power buzzes, and even cancellations. Originally developed to allow a SIM audio analyzer to be inserted into a sound system without deleterious effects, this patent is for an input circuit designed to avoid the injection of AC noise and provide the same gain no matter how the output feeding it is wired. The key to the circuit is that two transformers are employed in a serial, "hum-bucking" fashion such that any two of the three input pins will properly couple through one or both transformers without gain change while rejecting common-mode signals. Further, current transformers are used, rather than voltage transformers, so that the signal level passing through the transformers never reaches levels where common problems like eddy currents, ringing, phase shift, and hysteresis are encountered. The second patent describes an improved version of this circuit that uses a single, center-tapped transformer in place of the matched pair of transformers. Read More

Improved Ohmically Isolated Input Circuit
US Patent:	4,968,949
Date Filed:	October 17, 1988
Date Issued:	November 6, 1990
Inventors:	Michael Torrano, John D. Meyer, Bill Hemsath, Felicity Seidel
See Ohmically Isolated Input Circuit for more. These two patents are very closely related.

Correction Circuit and Method for Improving the Transient Behavior of a Two-Way Loudspeaker System
US Patent:	5,185,801
Date Filed:	July 18, 1991
Date Issued:	February 9, 1993
Inventors:	John Meyer, Paul Kohut
These two closely related patents describe technology that enables a two-way loudspeaker system to approach the theoretical ideal of a single point source. The first patent deals with direct radiating systems, and covers technology incorporated in the HD-1. The second patent, granted the following year, deals with specifics related to horn-loaded systems, and defined technology soon to be incorporated into the company's self-powered series of sound reinforcement products. Read More

Acoustical Ranging Transceiver
US Patent:	D357,678
Date Filed:	October 6, 1993
Date Issued:	April 25, 1995
Inventors:	John D. Meyer
A forerunner of the SB-1 Sound Beam, ARTS was used in conjunction with the SIM system for acoustical tests involving atmospheric inversion layer analysis. This patent covers the appearance or "ornamental design" of the device.

Correction Circuit and Method for Improving the Transient Behavior of a Two-Way Loudspeaker System
US Patent:	5,377,274
Date Filed:	November 22, 1993
Date Issued:	December 27, 1994
Inventors:	John Meyer, Paul Kohut
See Correction Circuit and Method for Improving the Transient Behavior of a Two-Way Loudspeaker System for more.

Method and Circuit for Improving the Polar Response of a Two-Way Horn-Loaded Loudspeaker System
US Patent:	5,784,474
Date Filed:	November 10, 1994
Date Issued:	July 21, 1998
Inventors:	Paul Kohut, Peter C. Soper, John D. Meyer
For this patent, Meyer Sound engineers developed control electronics and horn configurations that establish a common, fixed acoustical center for both the low-frequency and high-frequency drivers in a two-way horn-loaded system. The result is remarkably uniform sound radiation throughout the system's bandwidth — a breakthrough that enhances overall performance when multiple loudspeakers are combined in horizontal or vertical arrays. The technology was first implemented in the UPA-1P and UPA-2P, but has since been used in other Meyer Sound products. Read More

Loudspeaker (MSL-4)
US Patent:	D373,359
Date Filed:	December 13, 1994
Date Issued:	September 3, 1996
Inventors:	John D. Meyer, Peter Soper
The MSL-4 marked the beginning of the Self-Powered Series of sound reinforcement loudspeakers, a bold concept that today is changing the face of the entire industry. The MSL-4 enclosure, with its unorthodox low-frequency phasing plug, was awarded this design patent in 1996.

Multiple Tuned High Power Bass Reflex Speaker System
US Patent:	5,602,367
Date Filed:	December 19, 1994
Date Issued:	February 11, 1997
Inventors:	John Meyer
With the technology described in this patent, Meyer Sound took a quantum leap forward in boosting the efficiency of a direct radiating system to provide an optimum balance of compact size and efficiency. Rather than taking the conventional approach of using one or two drivers (usually of the same size) in a single reflex enclosure, this patent describes drivers of different sizes, each in its own acoustically isolated and specifically tuned chamber. In the MTS-4A, each driver also has its own dedicated power amplifier module and control electronics.

Loudspeaker (MTS-4)
US Patent:	D375,499
Date Filed:	August 9, 1995
Date Issued:	November 12, 1996
Inventors:	John D. Meyer, Jeffrey A. Weiner, Frank Kavka
This design patent covers the appearance, or "ornamental design," as the patent puts it, of the MTS-4. A separate patent, number 5,602,367, covers the MTS-4's innovative technology.

Broadband Acoustical Transmitting System (SB-1)
US Patent:	5,821,470
Date Filed:	April 8, 1997
Date Issued:	October 13, 1998
Inventors:	John Meyer, Paul Kohut
Highly directional loudspeakers are useful in several ways: they project sound further than the same acoustical output with wider dispersion, minimize reflections from walls and other surfaces, reduce off-axis interactions with other loudspeakers, and help to keep sound from spilling into areas where it is unwanted, such as residential districts neighboring an outdoor venue. Loudspeakers using a compression driver firing into a parabolic dish to focus sound into a narrow beam were well known at the time of the patent, but, in previous systems, the beam tended to fall apart and develop side lobes below a certain threshold frequency related to the size of the components, usually around 1 kHz. This patent is for the system used in the SB-1, which adds a 12-inch cone driver in the apex of the dish and filtering and phase manipulation circuitry that results in maintenance of the narrow beamwidth for another octave, that is, down to 500 Hz. The cone driver also increases the output level in the low range. Using this technology, the SB-1 essentially "repeals" the inverse square law and projects frequencies from 500 Hz to 15 kHz over extremely long distances. With the SB-1, even distant corners in large stadiums can be covered using a single-source cluster.

Loudspeaker Horn (CQ series)
US Patent:	5,925,856
Date Filed:	June 17, 1997
Date Issued:	July 20, 1999
Inventors:	John Meyer, Alejandro Antonio Garcia Rubio
Developments described in this patent came about in response to a specific problem encountered while designing a sound reinforcement system for the renovated San Francisco Opera House. The opera house's interior included large, very hard interior surfaces that would bounce back any frequencies straying outside a tightly defined coverage pattern. This made directional control in the loudspeakers of crucial importance. The horn design that is the subject of the patent was aimed at addressing this problem, and was developed through a process of theoretical modeling combined with iterative testing of prototypes in Meyer Sound's anechoic chamber. Most software programs applicable to horn design offer practical resolution of the coverage pattern only within a window of about five degrees, which was insufficient for the task at hand. This necessitated a painstaking series of tests to a resolution within fractions of one degree in order to realize the exacting precision required for the opera house system. The wording of the patent application is deceptively simple. However, subtle yet important innovations are involved in the complex interrelationship of shapes, relative dimensions and flare angles. For example, the pre-load chamber's rectangular opening is precisely phase-aligned to complement and correct response in the expanding section. The result is greatly improved polar frequency characteristics with virtually non-existent side lobing. The first CQ-1 wide coverage CQ-2 narrow coverage main loudspeaker systems were installed at the San Francisco Opera House in the fall of 1997, and introduced to the market in the spring of 1998. The CQ-1 horn is also used in the X-10 high resolution linear control room monitor, and a variation on that horn design is incorporated in the UPA-1P compact wide coverage loudspeaker.

Arrayable Two-Way Loudspeaker System and Method
US Patent:	6,081,602
Date Filed:	August 19, 1997
Date Issued:	June 27, 2000
Inventors:	John Meyer, Paul Kohut, Justin Baird
This patent describes two of the defining aspect of the UPA-1P, which are: constant directivity across frequency and the ability to be arrayed such that all speakers in the array share a common acoustic center, thus causing the array to act as a point-source in the way it radiates sound in the horizontal plane. This latter goal is achieved by creating a frequency independent focal point for the loudspeaker. Loudspeaker systems commonly change their radiation pattern with frequency. This leads to uneven coverage and undesirable interactions between loudspeakers in arrays. The system described in the patent (which is the UPA-1P, though not specifically named as such) uses a combination of horn design, signal conditioning, and iterative prototyping to arrive at a design exhibiting frequency independence in the focal point. The patent describes the system comprehensively, including the signal conditioning and arraying techniques.

Loudspeaker System with Feedback Control for Improved Bandwidth and Distortion Reduction
US Patent:	6,584,204
Date Filed:	December 10, 1998
Date Issued:	June 24, 2003
Inventors:	Khalid Al-Ali, Andrew Packard, Benson Tongue
This patent, issued to the University of California and licensed by Meyer Sound, defines the servo system used in the X-10 high resolution linear control room monitor, technology borrowed from the avionics industry. The patent defines a system for improving frequency response (magnitude and phase) in the sub-bass region of 20 – 100 Hz. Linearity is extremely difficult to achieve in this region, mostly due to three factors: non-uniformity in the magnetic field surrounding the voice coil, voice coil self-inductance variations with cone position, and the non-linear spring behavior exhibited by the surround and spider. The system described in the patent employs a microphone mounted in front of the low-frequency driver to acquire a pressure feedback signal from the drivers' audio output. This signal is then scaled and subtracted from the audio input signal (which is also scaled) to derive a difference signal. The difference signal is passed through a series of filters to generate a correction signal that is then applied to the loudspeaker. By placing the microphone very close and off-axis to the speaker, the delay time in the feedback is minimized, room effects do not affect the servo mechanism and cone breakup mode effects at higher frequencies are minimized (simplifying the task of modeling the driver's behavior). The filter network generating the corrected signal can be implemented digitally or with analog circuitry. The system offers advantages over other systems commonly applied to subwoofers in order to flatten response. One system applies an equalized signal to the driver, but the signal is fixed and is not derived from feedback on the system's operation, making it unable to compensate for modifying effects such as aging or environmental factors. Another system attaches an accelerometer to the voice coil, which adds mass to a critical component.

Frequency Dependent Excursion Limiter
US Patent:	6,931,135 B1
Date Filed:	October 9, 2001
Date Issued:	August 16, 2005
Inventors:	Paul Kohut
There are several ways that applying too much power to a loudspeaker driver can cause it to fail. One is overheating of the voice coil. Another one is over-excursion: when the applied voltage causes the driver to try to move further than it is mechanically able. Vented enclosures are particularly susceptible to this, especially below the tuning frequency of the enclosure, where the acoustical impedance becomes very low. There are several methods that are often tried for protecting against this. One is a standard limiter, but at the low frequencies of concern, they are often too slow when they need to be instantaneous. Further, very short attack times can sometimes produce artifacts. Another method is a high-pass filter, but they are not very effective and can introduce significant phase shifts that degrade the sound. Frequency-dependent limiters are a third method that has been applied. The frequency-dependent limiter triggers limiting at different levels for different frequencies, in accordance with measurements of the loudspeaker taken during the development phase to determine the maximum allowable voltage at those frequencies. In most cases, these limiters were used in open loop systems (that is, without a controller receiving feedback from the loudspeaker) and, as a result, had to be quite complex, involving matched filters and other difficult circuitry. This patent is for a greatly simplified circuit for a frequency-dependent limiter. Clever use of feed-forward and feedback circuits eliminates the need for matched filters. Other efficiencies are introduced by circuits that combine two functions that are separate in other frequency dependent excursion limiter designs. Overall, not only is the complexity of the circuit less, the parts count is also considerably reduced. Also addressed in the patent is the use of the limiter in a closed-loop system such as Meyer Sound's self-powered loudspeakers.

Manifold for a Horn Loudspeaker (REM)
US Patent:	6,668,969
Date Filed:	January 11, 2002
Date Issued:	December 30, 2003
Inventors:	John Meyer, Perrin Meyer, Richard Herr
Meyer Sound was awarded this patent for the REM ribbon emulation manifold, an innovative design at the heart of the mid- and high-frequency sections in Meyer Sound's line array and curvilinear array loudspeakers. The REM manifold's main advantages over other designs - lower distortion and tighter pattern control - are achieved due to its short length and exponentially increasing waveguide channels. Read More

Rigging System for Loudspeakers (M3D QuickFly)
US Patent:	6,640,924
Date Filed:	February 20, 2002
Date Issued:	November 4, 2003
Inventors:	Ian Strachan Messner
Meyer Sound was awarded a patent for the groundbreaking QuickFly rigging system developed for the M3D line array loudspeaker. The patent recognizes the rigging system's innovations including the CamLink system and the rigid design, which does away with the need for a pullback cable. The QuickFly system simplified setup, adjustment, teardown, and transport of loudspeaker arrays. Read More

Front of a Loudspeaker (MILO)
US Patent:	D505,942
Date Filed:	February 27, 2004
Date Issued:	June 7, 2005
Inventors:	John Meyer, Richard Herr, Paul Bunning
This design patent covers the appearance (or "ornamental design") of the front of MILO. The design is patented to prevent other companies from creating confusion in consumers with a product that looks identical.

Microphone
US Patent:	D508,691
Date Filed:	August 12, 2004
Date Issued:	August 23, 2005
Inventors:	John Meyer, Bruce Arasato, Stephen Starkweather, Peter Soper
This design patent is for the appearance (or "ornamental design") of a microphone created as part of a development project.

Ornamental Design of a Loudspeaker (MVC-5)
US Patent:	D547,749
Date Filed:	August 24, 2005
Date Issued:	July 31, 2007
Inventors:	Perrin Meyer, John D. Meyer, Bruce T. Arasato, Alejandro Antonio Garcia Rubio
This patent is for the design of the MVC-5 cabinet.

THE STORY

ABOUT PATENTS

Horn Speaker and Method for Producing Low Distortion Sound

Loudspeaker (UPA-1 Trapezoidal Cabinet)

Loudspeaker Enclosure (833 Studio Monitor)

Circuit and Method for Correcting Distortion in a Digital Audio System (Anti-Aliasing Filter)

Ohmically Isolated Input Circuit

Improved Ohmically Isolated Input Circuit

Correction Circuit and Method for Improving the Transient Behavior of a Two-Way Loudspeaker System

Acoustical Ranging Transceiver

Correction Circuit and Method for Improving the Transient Behavior of a Two-Way Loudspeaker System

Method and Circuit for Improving the Polar Response of a Two-Way Horn-Loaded Loudspeaker System

Loudspeaker (MSL-4)

Multiple Tuned High Power Bass Reflex Speaker System

Loudspeaker (MTS-4)

Broadband Acoustical Transmitting System (SB-1)

Loudspeaker Horn (CQ series)

Arrayable Two-Way Loudspeaker System and Method

Loudspeaker System with Feedback Control for Improved Bandwidth and Distortion Reduction

Frequency Dependent Excursion Limiter

Manifold for a Horn Loudspeaker (REM)

Rigging System for Loudspeakers (M3D QuickFly)

Front of a Loudspeaker (MILO)

Microphone

Ornamental Design of a Loudspeaker (MVC-5)