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Nursery School
Koutná, Vendula ; Jelínek, Petr (referee) ; Vajkay, František (advisor)
Master’s thesis „Nursery School" is proceed in form of project document, including all requirement according to standards and regulations. New building is located on parcel number 439/50 in city Přerov. Detached building has three floors and is partly cellarage. It is brick construction system based on packs. The roofs are flat, and constructed as single shell. Te floors are connected by prefabricated concrete staircase and by elevator. The nursery school is designed as a four departments building, with capacity of 96 children.
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Loudspeaker Box with Variable Crossover Frequency
Tomášek, Martin ; Balík, Miroslav (referee) ; Schimmel, Jiří (advisor)
This bachelor´s thesis deals with middle-sized loudspeaker system in D´Appolito configuration. The aim of this thesis is to design and to realize the loudspeaker system, which includes selection of suitable loudspeakers and their position in designed baffle including design of variable crossover frequency. The text is divided into a few sections, where are the points of this project described. In the first half there are briefly described basic principles of loudspeakers and design loudspeaker systems, especially 2-way loudspeakers, and specific properties of D´Appolito configuration. Then there are described principles of frequency crossovers used in loudspeaker systems and what is expected for their construction. In the second half, there is described realization of baffle itself and variable frequency crossover. Because this thesis concurs to semestral thesis, there is also a chapter about simulation. In the end there are diagrammatized the measured data of frequency and dispersion characteristics and a few dispersion characteristics for different crossing frequences.
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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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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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Loudspeaker Box for Wavefield Synthesis
Naňák, Pavel ; Kubánek, David (referee) ; Schimmel, Jiří (advisor)
Purpose of this work is to design active loudspeaker system as a source of sound proper for wavefield synthesis. Loudspeaker system is considerate as a singleband and its length should not overlap 15cm. System should be designed at the best in parameters like frequency characteristic and directional characteristic. Part of work is dedicated to theoretical aspects, explanation of wavefield principles itself and its usage on the field of surround sound, further this work concerns aural transducers, especially electrodynamic one, which is used in this work, and the last topic is about baffle-board for loudspeakers. Hereinafter there are laid two proposals of baffles, one conception is closed baffle and second is bassreflex baffle. Both of those baffle conception are simulated in program LEAP-5 and are optimized for this current work. All construction possibilities introduced in this work are digestedly documented in appendix. Special attention is dedicated to right choice of aural transducer for this loudspeaker and to description of its attributes, there are discussed pro and cons of every chosen transducer and its suitability for this work. Electronic part of work is designing of amplifier and power source suitable for at least four of loudspeakers. Amplifier is modified for switching input level of signal between -10 dBu and +4 dBu, this range is reached by switching the amplification of amplifier. Amplifier is realized in class D, because of the demands on small the size of the system. Amplifier is powered by external source designated to be small and effective at the same time. Each module of power source and amplifier has their schemes and designs of printed circuit boards are documented in appendix.
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Design and construction of subwoofer - low frequency loudspeaker unit
Holínský, Jan ; Schimmel, Jiří (referee) ; Balík, Miroslav (advisor)
This semestral thesis deals with the design and construction of deep-tone sound units –subwoofers and their use. There are listed descriptions of the individual types of sound systems, the possibilities of connecting the speakers with respect to the changes of the parameters speaker system, and then the design of the baffle with respect to the available materials. Moreover, the disassembled of VUE LMA hybrid solution is described. There are the mathematical relations for calculating the baffle parameters, furthermore there are also available basic programs for the design of the baffles. The purpose of this thesis is to get closer to the problem and to demonstrate the work with the simulation programs, a bandpass filter.
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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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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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efficiency of the bottom elements on the supercritical flow energy dissipation
Knoflíček, Jakub ; Haluza,, Miloslav (referee) ; Šulc, Jan (advisor)
The thesis is dealing with comparing dissipation of the kinetic energy water flow using various bottom elements based on model research. There is missing information about efficiency of different kinds of bottom elements. This absence does not allow to compare different modification of the bottom of stilling basins. Within experimental research were measured depths in different variants. Based on the results of model tests are evaluated and tabulated sorted variants of the combat efficiency of the kinetic energy water flow. The results will be used for the efficient and economic design of additional alterations of stilling basins.
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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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