I prefer valves, although might not want to complicate your life yte decide by a transistor amp with the latest technology modulacion.Te explain that ....
VALVES: (Tubes, Vacuum Tube, Triode, Pentode, etc.) Tubes operate by thermionic emission of electronesdesde a filament or cathode, controlled by a rejillay collection on a plate. Some tubes have morethan grid amplificadoresseparados Some have two elements in a glass envelope. These dual function valvulassuelen peor.Las characteristics of tubes varies widely dependiendodel selected model. In general, tubes are large, fragile, pretty, run hot and need variossegundos before operating. Tubes have gananciarelativamente low, high input impedance, low input capacity up, and the ability to withstand abuse momentaneos.Las Tubes overload (clip) gently and recuperandos suavemente.Los overload quickly and circuits that do not use tubes are called transistors (or state solid), they do not use devices that contienengas (or liquid). The characteristics of tubes tend to change with use (age). Are more susceptible to vibration (called "microphonics") than solid state devices. Lasvalvulas suffer from noise even when used with current filaments alterna.Las valves are designed for operation at higher voltages quecualquier other device, but high corrienteson valves rare and expensive. This means that most valves losamplificadores to use an output transformer. Despite not being specifically a tube characteristic, output lostransformadores added distortion of the second armonicoy show a gradual fall in response to high frecuenciasque is difficult duplicate with circuits.
TRANSISTORS: (BJT, Bipolar, PNP, NPN, Darlington, etc.) Transistors operate by minority carriers inyectadosdesde the emitter to the base that are swept labase through to the collector, controlling the flow of base.Los Transistors are available as PNP and NPN devices, allowing one to pull the output signal. The transistoresestan also available packaged as matched pairs, emitter follower pairs, arrays of transistors multiplese even as complex "integrated circuits", where estancombinados resistors and capacitors for circuit conseguirfunciones complejos.Como valves, there are many kinds of BTJs disponibles.Algunos have high current gain, while whichothers have lower gain. Some are fast, while others lentos.Algunos handle high current while others tienencapacidades lower input. Some are less ruidoque others. In general, the transistors are stable, last casiindefinidamente, have high gain, require some input Unheard, have low input resistance, higher input tienencapacidad, saturate quickly, and sonlentos to recover from overdrive (saturation). Lostransistores have a wide margin before saturacion.Los transistors are subject to a mode of llamadosegunda failure breakdown, which occurs when the device estatrabajando to high voltage and high current. The segundaavalancha can be avoided by conservative design, WHEREOF gave the first amplifiers transistoresuna bad reputation for reliability. Transistors are tambiensusceptibles of thermal runaway when seus incorrectly. However, the designs prudentesevitan second breakdown and runaway termico.MOSFET (VMOS, TMOS, DMOS, NMOS, PMOS, IGFET, etc.) The field-effect transistors metal-oxide semiconductor usanuna insulated gate to modulate the flow of portadoraprincipal power source to the drain with the electric field creadopor the door. Like bipolar transistors, MOSFETs are disponiblesen P and N. Also like transistors, MOSFETs are disponiblesen pairs and integrated circuits. MOSFET matched seacoplan not as well as bipolar transistor pairs, Peros valvulas.Los match better than MOSFETs are also available in many types. HOWEVER, all have low input current and input bajacapacidad enough. MOSFETs have lower gain, is saturanmoderadamente and recover quickly from saturation. Despite that power MOSFETs have no DC gate current, finite input capacitance means that MOSFETs have a gate depotencia AC finite. The MOSFETson stable and robust. Are not subject to runaway termiconi second breakdown. However, MOSFETs puedensoportar abuse as well as valvulas.JFET: Effect Transistors Junction Field exactamenteigual operate the MOSFET, but do not have a door aislada.Los JFETs share most of the characteristics of losMOSFETs, including available pairs, P and N, ycircuitos integrados.Los JFETs are not commonly available as power dispositivosde. They make excellent preamps Bajoru. The union of the door gives JFETs ingress policer greater capacity than MOSFETs and also prevents them from being used as accumulation or enrichment. JFETs unicamentese deplexing used as circuits or empobrecimiento.Los JFETs are also available as parejasy match almost as well as transistors bipolares.IGBT: (or IGT) Transistors insulated gate bipolar are a combination of unMOSFET and a bipolar transistor. Part dispositivosirve MOSFET as an input device and the bipolar as salida.Los IGBTs are currently available only as a device such as N, P coppers devices are possible in theory. IGBTs are lentosque other devices but offer a low cost, high capacity up current bipolar transistors with low Unheard input and low input capacitance of the saturation MOSFETs.Sufren much or more than lostransistores bipolar, and even suffering from second avalanchaRaramente used in High-end audio, but sometimes used paraamplificadores of extremely high power. Now the real question: You think that if they are so diversosdispositivos different from each other, one must be elmejor. In practice, each has its weak points fuertesy. Also, because each type of device estadisponible in so many ways, most lostipos can be used in most of the sites exito.Las Tubes are prohibitively expensive for very high power amplificadoresde. Most avalvulas amps deliver less than 50 watts per canal.Los JFETs are sometimes an ideal input device porquetienen low noise, low input capacitance and good acoplamiento.Sin But bipolar transistors have even mejoremparejamiento and profits, so that bajaimpedancia sources, bipolar devices are even mejores.Aun the tubes and MOSFETs have even lower capacity up entry, so for very high output resistance, podrianser mejores.Los Bipolar transistors have the lowest resistance desalted, so they make great output devices. However, the second breakdown and high stored charge weigh in contracuando be compared with the MOSFET. A good design BJT ceunta necesitatener in the weaknesses of BJTs while MOSFET design needs unbu disadvantages MOSFETsLos models require bipolar output transistors Protectionof second breakdown and thermal runaway and this proteccionrequiere additional circuitry and design effort. Insome amplifiers, the sound quality is damaged withthe proteccion.Como already said, there are more differences between individual designs, whether valves and transistors, which is between tube and transistor designs generalesentre. You can do a good amplificadorde either, and you make a lousy amp though tambien.A tubes and transistors clip differently, clipping will be rare or absent in a good amp, so this difference should be taken into people cuenta.Alguna claim that tubes require less or no unarealimentacion while transistoresrequieren significant feedback. In practice, Disable ALL amps require some feedback, seatotal, local, or just "degeneration." The feedback essential in amps because it makes amplificadorestable with temperature variations and manufacturable in spite of changes in componentes.La Feedback has a bad reputation because Queuña badly designed feedback system can vary dramatically passed. Some older designs usabanexcesiva feedback to compensate for not linealidadesde lousy circuits. Realimentacionesbien amplifiers that are stable and have designed a very small sobreimpulso.Cuando amps were first transistor, were worse than the best tube amps of aquellosdias. The designers made many mistakes with nuevastecnologias as they learned. Today, designers sonmucho more sophisticated and experienced in those days 1960.Debido to low internal capacitances, amplificadoresa valves have characteristics very lineales.Esto input makes tube amps tolerant alimentary easy to sources of high output impedance, talescomo other tube circuits and volume controls Dealt-impedance. The Transistor amps may have an essential high coupling between the input and output and may have an essential lower input impedance. However, some circuits tecnicasde reduce these effects. Even some transistors amplificadoresde completely avoid these problems by using circuits entrada.Hay buenosJFET as many exaggerations, errors as well as many leyendassobre the subject. Indeed, a good FET designer can make unbu FET amplifier. A good tube designer puedehacer a good tube amp, and a detransistores good designer can make a transistor amp HiThere. Many designers mix components to use them as they are mejores.Al As with all engineering disciplines, losbuenos amp design requires a broad conocimientode the characteristics of components, failure dediseño amplifiers, sourceofgrowthwas characteristics of the signal, characteristics of the loads, and signal caracteristicasde misma.Otro issue, we lack a good set of medidaspara rate the quality of an amplifier. The frequency response, distortion and signal-noise ratio give hints, but by themselves are insufficient to qualify people swear elsonido.Mucha tubes sound more "tube" and lostransistores sound more "transistor." Some people add a valve uncircuito their transistor circuits to darlesalgo sound "tube" Some people say they have measured a distinct diferenciasentre the distortion characteristics of amplificadoresde valves and transistors. This could be causadopor the output transformer, the function of transferenciade the tubes, or the choice of the topology of amplificador.Los tube amps rarely have enfrecuencia response as flat as the flattest detransistores amplifiers, due to the output transformer. However, the frequency response of good tube amps extremely good.
Subject: ESS.
Student: Pedro Jose Contreras Urbina
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