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Hybrid Microphone Preamplifier
Valach, Ondřej ; Hanák, Pavel (referee) ; Koton, Jaroslav (advisor)
The diploma thesis deals with the design of hybrid microphone preamplifier with stepless choice of amplification technology between active part using tube or semiconductor elements. Before the design, the basic physical relations of electroacoustics were described. Problems of connection of audio devices, their voltage and noise conditions. At last technical properties of microphones and tubes were described. In the practical part, the overall structure of the hybrid preamplifier is designed and the goals of the thesis are set. This is followed by a detailed design of the preamplifiers. From input circuits through individual amplifier stages of the semiconductor and tube sections to the output of the device. Much of the circuit was tested by software simulations. Based on the results obtained in the design of the signal part of the preamplifier, the power circuits were designed. Finaly the preamplifier functionality was verified by measurement on the Audio Analyzer.
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Tube Microphone
Škoda, Adam ; Šotner, Roman (referee) ; Staněk, Miroslav (advisor)
The presented thesis deals with a tube microphone using a condenser microphone capsule for sound capturing. Moreover, two essential aspects of a tube microphone – the basis of its operation and its design – are also discussed in this thesis. In the designed microphone, there is a vacuum tube known as ECC81. This vacuum tube is used as an amplifying element of an input sound signal. This paper also includes the choice of the most suitable microphone circuit, its modification and the design of a voltage source used for feeding and heating the vacuum tube. Some appropriate simulations were applied to find out the functionality of all designed parts of the microphone system. Following step was the practical realization of all microphone parts as well as the activation and the complete parameters and characteristics measurements of realized microphone system. After the provided measurements, the microphone was compared to equivalent commercial products. Evidently, the realized microphone is qualitatively similar to other commercial products. Presented thesis also contains the list of components and PCBs.
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Design and properties of low-frequency amplifier with vacuum valves
Piroha, Ladislav ; Musil, Vladislav (referee) ; Šandera, Josef (advisor)
The purpose of the bachelor’s thesis is explanation of theory and construction of low frequency tube audio amplifier with UV meter. Main focus is on history and development of vacuum circuits from its early beginning, on electrical parameters and applied physical principles. Explanation of operating characteristics of amplifier classes and comparison of vacuum tube sound acoustic performance against transistor amplifier one. Finally, there is build description of single ended amplifier class A.
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Design and construction of a tube guitar amplifier
Šona, Štěpán ; Dvořák, Jan (referee) ; Kubánek, David (advisor)
The text of this bachelor’s thesis deals with the design, simulation and construction of a tube amplifier for electric guitar, based on the well-known guitar amplifier VOX AC 30. The theoretical part deals with the design and simulation of the original circuit. Subsequently, adjustments were made on both channels and simulated. The practical part of the work already deals with the construction itself, measuring the finished guitar combo. Frequency modulus characteristics, harmonic distortion, spectra and time courses of signals for distorted and clear channel were measured. Then the measurement was evaluated.
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Hybrid microphone preamplifier with variable selection of amplifier technology
Musil, Tomáš ; Levek, Vladimír (referee) ; Háze, Jiří (advisor)
This diploma thesis deals with a basic description of dynamic and condenser microphone, its performance regarding polar patterns and a type of mechanical construction. It also describes a principle of operation of a triode. The thesis deals with selecting of a suitable type of microprocessor to control microphone preamplifier functions. Last part contains a power supply and microphone preamplifier circuits design using a semiconductor and vacuum tube technology.
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Class A audio power amplifier with tubes
Krutílek, David ; Brančík, Lubomír (referee) ; Kratochvíl, Tomáš (advisor)
The topic of my bachelor´s theis is of the class A audio power amplifier using vacuum tubes which is completed with phono preamplifier and input selector. There are used ECC 83 and ECC 88 vacuum tubes for the pre-amplifier design, then EM 84 tubes for the „eye-magic“ equalizer and 300B tubes for the power amplifier design. The maximum output power is 2 x 20W to 8 ? load. In this paper there are presented schematics of the pre-amplifier and power amplifier too. The aim of this bachelor´s project was make complete design of laboratory prototype (scheme, layout of printed circuit, part list and placemnet), realisation function of prototype and laboratory measurements.
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Vacuum tube phono amplifier
Hrubý, Ondřej ; Novák, Lukáš (referee) ; Musil, Tomáš (advisor)
This master´s thesis deals with a design and simulation of an audio power phono amplifier using vakuum tubes. The frequency response of suggested solution should comply with the norm specified by RIAA. It also describes a vacuum tube basic description and also its advantages for audio applications and principle of usage a magnetodynamic pick-up. Last part contains a design of microprocessor system and power supply.
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Class AB stereo audio power amplifier with electron tubes
Herbrych, Vojtěch ; Šotner, Roman (referee) ; Kratochvíl, Tomáš (advisor)
Bachelor thesis deals with design and create construction drawings of audio amplifier using vaccum tubes with output power 20 W/4 and works in class AB. At least two inputs are included for mobile, computer and others. The device includes 2-band preamplifier with basic adjustment (bass and treble). For different channel volume is included balance adjustment. There is an audio-level indicator with „magic-eye tube“. This part of bachelor thesis contains theoretical explanation, design of amplifier´s schematic and design drawings.
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Analog distortion musical signals
Růžička, Matěj ; Kubánek, David (referee) ; Vrba, Kamil (advisor)
In this bachelor thesis I studied the differences in sound of valve amplifiers and solidstate amplifiers, causes of those differences, mathematical modelling the transfer characteristic of valve amplifier and then modeling it with simple diode limiter, which used several types of semiconductor diodes, Properties of those diodes were measured as well. Then I constructed limiters for both polarities of input signal, which had non-linear transfer characteristics similar to the valve amplifier and I evaluated their qualities. Then I measured simple amplifier with bipolar transistor, JFET N-channel transistor and optocoupler, Furthermore, I modified triangle-to-sine converters with bipolar transistor, JFET N-channel transistor, measured and evaluated their transfer characteristics. At the end of this bachelor thesis I described designing a diode-based functional converter and converter made from several bipolar transistors, both of these had similar shape of transfer characteristics and I evaluated their qualities by comparing weighted harmonic distortion of the output signal with output signal of tube amplifier.
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Vacuum tube headphone amplifier
Musil, Tomáš ; Kledrowetz, Vilém (referee) ; Háze, Jiří (advisor)
This Bachelor’s thesis deals with design and realization of vacuum tube headphone amplifier working in class A. There is a closer look into operating principals of vacuum tube, most common types, basic ways to use it in electronic circuit, designing stabilized power supplies and also realization of functional prototype and measuring it’s parameters.
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