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Loudspeaker Box for Laboratory Measurements of Loudspeaker Impedance
Nevole, Tomáš ; Káňa, Ladislav (referee) ; Schimmel, Jiří (advisor)
In this thesis there are solved problems of design and construction of a universal modular loudspeaker box, which should serve for laboratory measurements of broadband electro-magnetic loudspeaker’s impedance. These measurements should demonstrate how the electric parameters are changed by changing the acoustic impedance of surrounding into which the speaker transmits. In the first part there is explained necessary theory for solving the task, such as way of sound’s transmission in the environment, variable sorts of speakers and their characteristics. A special focus is given to description of the electro-magnetic speaker’s parameters and construction that was used for the loudspeaker box. Then there are introduced needed mathematical formulas for algebraic design of the loudspeaker box, various types of the loudspeaker boxes (open, closed, vented) and their parameters. In this thesis there is also solved the problem with leaks and settled the matter, if it is better to build one modular box or 2 or 3 separate boxes. Most important characteristics are the impedance characteristics for this thesis but the SPL characteristics are also included. Unfortunately the simulating programs couldn’t generate the hodographs of impedance. After the algebraic calculations, in the thesis there are presented outputs from simulation programs Unibox 408 and WinISD 0.6. The outputs also are compared with the algebraic calculations. In the last part of the thesis there is already described the own construction of the loudspeaker box and presented results from the box’s measuring in the anechoic chamber (in the laboratory of electro-acoustic). The measuring of the modular impedance characteristic was realized on the single speaker and all the boxes. The measuring of the SPL (sound pressure level) characteristic was realized on the boxes only. All these results are compared with the calculations and simulations and the inaccuracies are substantiated in the end. The comparing of the manufacturer’s characteristics with the measured characteristics is also included.
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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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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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Loudspeaker design for home environment
Šafer, Radim ; Schimmel, Jiří (referee) ; Kratochvíl, Tomáš (advisor)
The subject of my bachelor‘s thesis is a design of the loudspeaker for home listening. Foremost I focused on simulations of the loud-speakers, which I use to a design itself. The loudspeaker is a two-way and stereophonic, which is optimised for a woofer Beyma 6B30/P and a tweeter Beyma T2010. The enclosure is closed, made of the M.D.F. material. The vibration damping is ensured by a polyester damping cottonwool. The maximum standardised wattage of the loudspeaker is 50 W, nominal impedance is 8 ?, internal capacity is around 15 litres, sensitivity 90 dB and weight 10 kg.
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Audio speaker system with baffle made from alternative materials
Hüttl, Ondřej ; Schimmel, Jiří (referee) ; Kratochvíl, Tomáš (advisor)
This thesis firstly consists of an analysis and a description of materials suitable for construction of loudspeaker enclosures and a design of the loudspeaker system with the enclosure made of a synthetic stone. Electro – acoustics drivers have been described with a focus to a frequency range, a principle and a construction for an explanation of their function. Drivers based on electrodynamic principle have been described closely. An analysis of materials used for the loudspeaker enclosure production has been done and tradicional and alternative materials have been described as well. Specific modulus, density and stiffness have been taken as an objective evaluative criterion. An evaluation indicates appropriate properties of plastic, aluminum and stone based materials. The function and kinds of loudspeaker enclosures have been described. The function, properties and design of a vented box loudspeaker system have been described closely. The last part of this thesis is individual design of a two-way vented box loudspeaker system with the enclosure made of synthetic stone. A simulation of a driver behavior built in the enclosure and compensation circuits and crossovers design and simulation have been done. The enclosure has been designed with high stress to minimize negative effect of the enclosure to the final sound quality.
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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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Laboratory design of a speaker system
Šulc, Martin ; Schimmel, Jiří (referee) ; Špiřík, Jan (advisor)
The bachelor thesis deals with the project of loudspeakers using freely available computer softwares. The thesis is focused on creation of a laboratory exercise called Laboratory design of a speaker system. The basic quantities describing acoustic wave motion and the principles of acoustic spread are explained there. There are also described different parts of loudspeakers like cabinets, loudspeaker drivers and electrical crossovers. Different softwares were chosen for the design. The descriptions of the most convenient programs for the laboratory exercises are introduced in the thesis. The laboratory exercise is devided into three parts. In the first part there is a brief theoretic introduction, the second part describes the control of the chosen software and the third part deals with the topic of this thesis. I have chosen two different sreeware softwares the most convenient for the construction of loudspeakers.
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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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