Loudspeaker as a treatment for room acoustics

This paper deals with possibilities of using the loudspeaker for room acoustic. The experiment with large low resonant frequency loudspeaker was done. At first, the vibration of membrane was scanned by using a laser vibrometer for different operating states. The effect on reverbereation time of placing the loudspeaker in echoic chamber was also investigated

Construction of amplifier for guitar

Tato bakalářská práce je zaměřena na návrh a konstrukci elektronkového zesilovače určeného pro elektrofonickou kytaru. Zesilovač má dva kanály, efektovou smyčku, koncový zesilovač s výkonem pro použití v domácích nebo studiových podmínkách a polovodičový usměrňovač. První část práce obsahuje teoretický úvod do problematiky nástrojových zesilovačů a popis používaných řešení u komerčně vyráběných zesilovačů. Další částí je návrh jednotlivých bloků zesilovače. V závěru jsou shrnuty výsledky po testování zesilovače.Katedra aplikované elektroniky a telekomunikacíObhájenoThis bachelor thesis deals with the design and construction of vacuum tube amplifier for electrophonic guitar. The amplifier has two channels, the effects loop, power amplifier with performance for using at home or in studio and semiconductor rectifier. The first section contains theoretical introduction to the instrumental amplifiers issue and solution description commonly used in commercially produced amplifiers. Another section is focused on amplifier blocks design. Testing amplifier results are discussed in the end

Měření akustických rezonančních pohltivých prvků

Tento článek vznikl za podpory interního projektu na podporu studentských vědeckých konferencí SVK-2018-005 a projektu SGS-2015-020: Vícekanálové měřicí metody.This paper deals with possibilities of measuring resonance frequency of absorbing elements using the loudspeaker. Commonly used methods for determine absorbtion coefficient α are not suitable for prototypes design. For verification in the reverberation chamber a large sample area is required. In impedance tube can be measured only small circular samples. The method, which is described in the paper, is based on change of the loudspeaker impedance characteristics due to placing prototype of the absorbing element into a common baffle

Possibilities of verifying the parameters of the absorbing elements using the loudspeaker

This paper deals with other option of determination of the acoustic absorbing materials parameters. Simplified procedures are often used to design new absorbing elements. These procedures are based on an ideal model or previous experience. The result is often quite inaccurate. To verify the absorption coefficient α, measurements in the reverberation chamber or impedance tube are required. Both of these methods require expensive and special equipment, which is not available to everyone. For measurement in the reverberation chamber it is necessary to have approx. 10 m2 of the measured sample. In the impedance tube there are measured only small circular samples and the coefficient α only for the perpendicular impact of sound waves. Thus, these methods are not suitable for designing prototypes of new absorbing elements. For this reason, other possibilities for determination of important parameters on a relatively small prototype sample were investigated. The result of this research is an experiment describing a possible measurement method. This method is based on change of the loudspeaker impedance due to placing prototype of the absorbing element into a common baffle

Measurement of parameters of the eCall system transmission channel for passenger car

Emergency call system, which in the case of traffic accidents ensure rapid assistance to motorists, will be mandatory for all new passenger cars approved since 2017 - 2018. The speech intelligibility as one of the parameters of eCall developed for cars depends on parameters of the transmission channel. Due to the internal design and arrangement of the car interior, there are not many suitable variations of speaker location in terms of quality of speech transmission. Therefore, ITU standards provide the recommended values and measurement procedure of important parameters. The paper deals with methods of measurement RLR, THD and SNR parameters inside the car

Design and Characterization of Embroidered Electroacoustic Transducer

This paper is focused on designing and characterization of embroidered electroacoustic transducer placed on the magnet. This type of transducer can be used as a feedback or notification element in an advanced smart textile system. Multiple transducer designs and threads were used in the experiment. Results from measuring of acoustic level have showed, that embroidered electroacoustic transducer can be used as a full-featured speaker for the feedback system. The results have showed the ability to play simple sounds and melodies through this electroacoustic transducer.This paper is focused on designing and characterization of embroidered electroacoustic transducer placed on the magnet. This type of transducer can be used as a feedback or notification element in an advanced smart textile system. Multiple transducer designs and threads were used in the experiment. Results from measuring of acoustic level have showed, that embroidered electroacoustic transducer can be used as a full-featured speaker for the feedback system. The results have showed the ability to play simple sounds and melodies through this electroacoustic transducer