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| Тема |
 Re: Що е то Class H+ [re: дp.Kиpилoв] |
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| Автор |
CMEHA (8М) |
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| Публикувано | 09.01.03 15:24 |
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Клас-G било стъпково усилване на захранването, при по-силен сигнал (2 или 3), а клас-Н било "следящо" - tracking захранване, т.е. плавно. Не разбрах защо обаче имало по два усилвателя на канал. И странното е, че един друг модел (не помня 100, или 140 му са цифрите) е същия, но по-евтин, а е с 2 чифта колони и не е клас-Н ?! Сигурно е както ти обякняваш - единия усилвател прави нещо на другия. гарантират 2 пъти пикова мощност над номинала, без clip-ване на сигнала.
Намерих едни статийки за видовете усилватели, ама не ми се копират, да не раздуваме темата. На мен ми стана ясно, доколкото разбирам от тези работи.
ето да е интересно и на другите:
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class G
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This class operation involves changing the power supply voltage from a lower level to a higher level when larger output swings are required. There have been several ways to do this. The simplest involves a single class AB output stage that is connected to two power supply rails by a diode, or a transistor switch. The design is such that for most musical program material, the output stage is connected to the lower supply voltage, and automatically switches to the higher rails for large signal peaks [ thus the nickname rail-switcher]. Another approach uses two class AB output stages, each connected to a different power supply voltage, with the magnitude of the input signal determining the signal path. Using two power supplies improves efficiency enough to allow significantly more power for a given size and weight. Class G is becoming common for pro audio designs. [Historical note: Hitachi is credited with pioneering class G designs with their 1977 Dynaharmony HMA 8300 power amplifier.]
Class G improves efficiency in another way: an ordinary class AB amplifier is driven by a multi-rail power supply. A 500 watt amplifier might have three positive rails and three negative rails. The rail voltages might be 70 volts, 50 volts, and 25 volts. As the output of the amplifier moves close to 25 volts, the supply is switched the 50 volt rail. As the output moves close to the 50 volt rail, the supply is switched to the 70 volt rail. These designs are sometimes called "Rail Switchers". This design improves efficiency by reducing the "wasted" voltage on the output transistors. This voltage is the difference between the positive (red) supply and the audio output (blue). Class G can be as efficient as class D or T. While a class G design is more complex, it is based on a class AB amplifier and can have the same clean characteristics as well.
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class H
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Class H operation takes the class G design one step further and actually modulates the higher power supply voltage by the input signal. This allows the power supply to track the audio input and provide just enough voltage for optimum operation of the output devices [thus the nickname rail-tracker]. The efficiency of class H is comparable to class G designs. Class H amplifier works much like a combination of an A(B) and D amplifier. It has the low cost of the Class A(B) amplifier, has a similar frequency response, has lower distortion levels and better battery life. The current drain depends on the level of the incoming signal. [Historical note: Soundcraftsmen is credited with pioneering class H designs with their 1977 Vari-proportional MA5002 power a mplifier.]
Class H is similar to class G, except the rail voltage is modulated by the input signal. The power supply rail is always just a bit higher than the output signal, keeping the voltage across the transistors small and the output transistors cool. The modulating power supply rail voltage is created by similar circuitry that you would find in a class D amplifier. In terms of complexity, this type of amplifier could be thought of as a class D amplifier driving a class AB amplifier and is therefore fairly complex.
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Редактирано от CMEHA на 09.01.03 16:07.
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