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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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Active Loudspeaker Crossover with DSP
Václavík, Jiří ; Fedra, Zbyněk (referee) ; Povalač, Aleš (advisor)
Semestral thesis is devoted to mapping and verification technologies for the project active loudspeaker crossover using DSP. Three way systém will use open baffle. Design of analog crossover is complex due to the need of compensating for acoustic short circuit and properties of laudspeakers.
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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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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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Amplifier with Speaker Protection
Přibyl, Libor ; Schimmel, Jiří (referee) ; Kubánek, David (advisor)
The present work deals with the issue of speaker damage due to large displacement of the membrane at low frequencies. The main focus is the design and construction of the circuit to protect the speakers from this type of damage and the subsequent measurement of its parameters. The thesis includes theoretical predictions for the optimal design and implementation of the circuit. The work includes complete construction of equipment, including power supply and auxiliary circuits.
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Multifunction speaker with wireless connectivity
Baránek, Michal ; Kratochvíl, Tomáš (referee) ; Kufa, Jan (advisor)
Tato práce se věnuje multifunkčnímu systému s více možnostmi pro přenos zvukového signálu do reproduktoru. Problémem u dnes velmi populárních komerčních přenosných reproduktorů je absence autonomního zdroje hudby, například v podobě rádia. Proto je cílem této práce právě dosáhnout takového multifunkčního reproduktoru podobnému jako jsou komerční přenosné reproduktory, ale s možností přehrávání radia distribuovaného pomocí internetové sítě. Další z nejdůležitějších funkcí těchto reproduktorů je bezdrátové připojení, jako je Bluetooth, pro streamování zvuku, například z telefonu do reproduktoru. Další významné aspekty těchto reproduktorů jsou jednoduché uživatelské rozhraní, převážně ve formě ovládacích tlačítek, kvalitní zvukový výstup s přiměřeným výstupním výkonem k velikosti reproduktoru a velkou výdrží baterie pro několika hodinový poslech na nízké nebo střední úrovni hlasitosti. Proto jsou i tyto všechny funkce implementovány v této práci výroby multifunkčního reproduktoru.
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Design and Implementation of Active Loudspeaker System with Digital Input
Uchytil, Filip ; Balík, Miroslav (referee) ; Schimmel, Jiří (advisor)
The work is focused on a design of an active loudspeaker system with a bi-amp amplifier and a digital input. There is described the theory of a loudspeaker enclosure design and its practical implementation. Furthermore the work deals with a design and construction of input circuits such as a preamplifier, Baxandall tone control, active crossover, all-pass filter and S/PDIF. On the basis of the amplifier´s theory the optimal construction of amplifiers and their design are selected. The complex design of the loudspeaker box is devised so that it would reach a maximum acoustic power during the preservation of a low distortion.
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Power audio amplifier with two-way speaker system
Rystvej, Matej ; Petržela, Jiří (referee) ; Kratochvíl, Tomáš (advisor)
The aim of this bachelor thesis was a design of a stereo amplifier with an appropriate loudspeaker system for home listening. The amplifier has the ability to be switched over between high and low output power mode. This means it is possible to be used also with an other loudspeaker system with lower input power rating, and it will be prepared for possible future implementation of an active frequency filter, which will fit the frequency response to this designed loudspeaker system by amplifying some frequencies. This thesis contains design of the softstart circuit, power amplifier, preamplifier circuit, the output power switch, the delayed loudspeaker connecting circuit and the loudspeaker system.
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Universal passive frequency crossover - laboratory device
Pacek, Dominik ; Hanák, Pavel (referee) ; Balík, Miroslav (advisor)
The aim of this work is to theoretically outline the issues associated with design of a passive crossover network in the context of speaker system design and the solutions to the mentioned issues.The practical part of the work deals with the design of a laboratory passive crossover network, it’s construction and creation of laboratory task utilizing the crossover network for teaching loudspeakers and speaker systems course.
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