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Loudspeaker System for Laboratory Measurements of Polar Patterns
Morkus, Filip ; Káňa, Ladislav (referee) ; Schimmel, Jiří (advisor)
In the first part the attention is aiming to the choice of suitable loudspeakers. For this choice it was necessary to set required criteria and parameters. The aim of the system was to have as wide reproducibility range of frequency as possible but on the other hand not to be too large. The other criterion was the quality of the loudspeakers and its price. In the second part there was frequency crossover suggested according to the parameters of the chosen loudspeakers. This was suggested for low frequency spectrum as well as for high frequency spectrum. When determining the dividing frequency there were thought over producer’s recommendations and frequency characteristics of the loudspeakers so that the dividing frequency was not set in the place where the loudspeaker does not have “constant” character. The third part concerns the construction of the loudspeaker case. There one can find more details about the construction of the loudspeaker system called D´Appolito and its constructional requirements. This part was kept to the previous parts because integrating “D´Appolito” needs setting the distance between the loudspeakers according to the dividing frequency. It was also necessary to count with their size. According to the loudspeakers parameters it was possible to calculate the capacity of the loudspeaker case, also its shape was said and geometric proportions were calculated. Then everything was simulated in suitable software. In the last part the complete loudspeaker system was measured in an anechoic room. There were the direction characteristics and frequency characteristics measured there. The results of the measuring were compared with the software simulations.
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Automotive audio amplifier and subwoofer
Kolka, René ; Šotner, Roman (referee) ; Dřínovský, Jiří (advisor)
This thesis deals with the project of two performance amplifiers for a subwoofer and for four basic car loud-speakers. The following part of the thesis is dealing with the power circuits of the amplifiers. The control of the amplifiers is realized by processor. The thesis is also dealing with the problems caused by sound system installation in a car, and concerns mainly with the boosters position and with producing high quality subwoofer and baffle-board.
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Measuring Loudspeaker System for Laboratory Practices
Tomešek, Jiří ; Balík, Miroslav (referee) ; Schimmel, Jiří (advisor)
This bachelor's thesis deals with the design of a two-way speaker system and a variable baffle for a subwoofer for the purposes of demonstration measurement in the subject of Electroacoustics. The theoretical part explains the individual speakers, TS parameters and formulas for their calculation. Furthermore, various types and constructions of baffles and audio crossovers. Using the simulation program LspCAD, the designs of closed and bass reflex baffles with right and wrong parameters were fine-tuned and simulated. The proposed crossover for a two-way speaker system was also simulated. Drawing documentation was prepared for the designs. Furthermore, the baffles and crossovers were implemented, and their characteristics were measured. Finally, the existing laboratory tasks were reworked so that students could use the implemented baffles and the chosen design procedure.
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Compensation of loudspeaker measurements using standard baffle
Štěpáník, Jiří ; Schimmel, Jiří (referee) ; Balík, Miroslav (advisor)
The frequency response of the loudspeaker is one of the key data that needs to be known, for example, when designing a speaker cabinet or speaker system. The frequency response should be achieved with the highest possible accuracy and with a minimum of distortion. How to achieve such characteristics is described in the standard ČSN EN 60268-5, which states as one of the ways the use of standard enclosures. Except for the standard baffle, these baffles have correction curves for the measured characteristics described in the standard. However, this does not mean that the standard baffle does not distort the measurement. The aim of this work is to analyze the distortion of measurements caused by this baffle and other elements and their compensation. The work contains a description of certain parts of the standard ČSN EN 60268-5 with focus on the standard baffle. Especially on its construction and methods of measuring the speakers mounted on it. Several test measurements were performed within the work. These measurements were performed in a anechoic chamber with speakers mounted on a modular standard baffle, which is a modification of the standard baffle which is also described in the work. The measurements performed include the measurement of frequency characteristics at different distances of the microphone from the speaker at different positions of the baffle in the anechoic chamber. The test measurements show that the modular standard baffle and anechoic chamber cause measurement distortion. In other measurements, the distortion by the anechoic chamber is minimized and the distortion caused by the base of the modular standard baffle is completely eliminated. The thesis then presents the theory of sound diffraction at the edges of a standard baffle and the theory of the extended Biot-Tolstoy-Medwin method of modeling these diffractions using numerical calculations. Based on this theory, software compensation of diffraction distortion was performed in Matlab. It is not entirely clear from the results of the compensation to what extent it can be considered successful. It can be speculated that it only works on certain frequencies. It is necessary to verify the functionality of this compensation method by another test measurement.
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Loudspeaker System for Reproduction of Low Frequencies with Directional Radiation
Skvaril, Šimon ; Husník, Libor (referee) ; Schimmel, Jiří (advisor)
Final product of this work is design of speaker baffle which will have directional radiation at low frequencies. In the course of the work, propagation of sound waves and their beaviour at obstacles are described. The computational method FDTD and the K-wave toolkit for MATLAB, which uses this method, are described. In MATLAB a virtual model of speaker baffle is created and proposed solution is verified. Next step is creation of scaled model of speaker baffle on which agreement of theoretical computations with real-world measurment is verified. Final step is creation of prototype of speaker baffle,, whose parameters are measured, including polar response.
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Standard baffle - laboratory device
Hodinka, Tomáš ; Říha, Kamil (referee) ; Balík, Miroslav (advisor)
The purpose of this project is the design and the construction of a laboratory preparation for loudspeaker measurements, a standard baffle. Standard baffle is a rectangular panel with a loudspeaker placed eccentrically. Measurements with this baffle are then done in an anechoic chamber. The main purpose of a standard baffle is the ability to measure loudspeakers without the effect, that is caused by the pressure properties of a closed baffle and without an acoustic short circuit. The standard baffle is designed, so that it is self-supporting, transferable by 2 people, easy to be stored, modular and able to support loudspeakers that are up to 12 inches in diameter. The designed baffle is detachable into 3 parts. The base, the panel, and the inserts. The base is a big, heavy board with a key on the upper side. This key fits into a key groove in the panel and that allows the two parts to assemble. The plane is made of four layers of different types of plywood. That allows the design to make a compromise between the toughness and weight. The inserts are designed, so that the replacement and manipulation of loudspeakers during measurement are as past and as simple as possible. During measurement the loudspeakers are mounted in their respective inserts, which can be mounted and dismounted from the standard baffle without any tools. The test measurements demonstrated that the standard baffle is unsuitable for reference measurements. Resonance of the plane, reflections from the base, refractions from the outer edges of the baffle and potentially different causes unduly distort the results of measurements. These distortions are displayed with a considerable consistency even between different loudspeakers. This indicates that these distortions could be filtered oud by, for example, using a specialized software.
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Design and Construction of Transmission Line Loudspeaker Cabinet
Dobiášovský, Jiří ; Schimmel, Jiří (referee) ; Balík, Miroslav (advisor)
Thesis is dealing with the topic of design and construction of the transmission line loudspeaker enclosures. Theoretical part is focused on speaker choice, its design elements and their influence on parameters of the speaker. Individual parameters of the speaker, mathematical equations for their determination and choice of suitable speaker for transmission line loudspeaker enclosure is furthermore discussed and defined. Principle of transmission line enclosures is discussed together with its advantages and disadvantages compared to other types of enclosures. The individual design elements and their influence on the resulting characteristics of the enclosure are described. In the practical part, with regard to the facts stated in the theoretical part of the work, a suitable speaker is selected and the subsequent design and construction of a variable transmission line speaker is described. This might serve as a teaching aid in future. Part of the work is also a description of procedures for measuring loudspeakers with multiple speakers or resonators.
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Variable Two-Way Loudspeaker Cabinet - Laboratory Tool
Rehák, Jan ; Schimmel, Jiří (referee) ; Balík, Miroslav (advisor)
The objective of this work is to build a two-way loudspeaker system that will enable changing loudspeaker topology in both vertical and horizontal axes and to suggest two laboratory tasks. The theoretical part of this work will briefly discuss loudspeaker crossovers. Then it will discuss how topology of loudspeakers in a loudspeaker system can affect its behavior at crossover frequency. Frequency characteristics of various loudspeaker baffles will be shown. On these, the effect of a baffle’s exterior on its behavior will be discussed. A two-way loudspeaker system will be designed. The construction process and drawings of each part are also included in this work. The finished product will be tested and, following from these tests, a conclusion will be drawn about the validity of the theoretical assumptions of its design. After that, appropriate parameters of a crossover for the two-way loudspeaker system will be chosen.
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Subwoofer for PA applications
Tylich, Ondřej ; Červinka, Dalibor (referee) ; Martiš, Jan (advisor)
The content of the bachelor´s thesis is theoretical knowledge in the field of loudspeaker baffles, their construction and design of the subwoofer according to the assignment. The work describes various types of used loudspeaker baffles. Their properties are defined for each of them. Some of the simulation programs are used for proper design. A suitable speaker is selected for the subwoofer application in PA technology. The parameters of the selected loudspeaker are verified by measurement. Based on these parameters, the design of the selected loudspeaker is calculated. Furthermore, the thesis addresses deals with the complete design process of the baffle for the selected speaker and its subsequent construction. After the construction, the port is tuned to the selected parameters. The resulting parameters of the designed subwoofer are verified by measuring the amplitude and frequency characteristics.
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