Transistor amplifier driving force depends on what factor is the output power or the power supply? Why do some feel more than 60W power amplifier 100W in there sounds fresh?
amplifier drive ability is not by a factor individual decision, it is the combined effect of many factors, according to current research, at least the following factors: power supply, output power, damping coefficient, the ability to resist the back-EMF. Perhaps, if we look at the issue from the perspective of the speaker, may more clearly. Ease of the speaker driver with the following factors: the trend of impedance curve, sensitivity, phase angle of the excursion, the strength of EMF.
said first impedance curve. We know that speakers have 4Ω, 6Ω, 8Ω and other specifications, in fact, these figures are only at a certain frequency the impedance on the nominal value, does not mean that in any case are constant impedance 4Ω, 6Ω, 8Ω. With 8Ω speakers, for example, from the impedance curve can be clearly seen, there is no resistance to a box from 20Hz to 20kHz has been maintained at 8Ω position, it will change with changes in frequency, sometimes high enough to dozens of Europe, sometimes as low as four ohms. Impedance curves have anything to do with the amp?
Do not forget, the power amplifier output power and load impedance (that is, the speaker impedance) is directly related, if an amplifier in an 8Ω nominal a 100W output, 16Ω output when it can only 50W, 32Ω even lower when only 25W output. Instead, the amplifier output at 4Ω may be increased to 200W, 2Ω, also may increase to 400W. Please note that changes when the speaker impedance is high, the equivalent of the power amplifier load lighter, when output power is reduced in proportion to it, will not cause any burden on the amplifier. However, when the speaker impedance decreases, the amplifier's output to more than just bigger so simple.
first problems encountered in the power amplifier is able to provide such a large part of output power required? If not, can not be achieved when the 4Ω 200W output, not to mention 2Ω 400W output reached the. If the power supply really that big power reserve, the power required to meet the 400W, we also consider another problem: the output transistors can withstand so much of the current do?
Typically, manufacturers are unlikely to 400W 100W spend on the machine after the power transistor required level, because this way, the cost will be substantially increased. Thus, except for a few at the expense of Hi-End products, most of the power amplifier load impedance can not be reduced in proportion to growth in output power. To increase the number, depending on the amplifier's power capacity and output power control specifications.
different machine design and power output tube there is a difference, when the load impedance changes (lower), the possibility of making the results of theoretical calculations increases in proportion to the ability of the output power will vary, and thus resulted in differences in the intensity of the sense of hearing.
surface sensitivity of the issue is very simple, 90dB sensitivity, the box should be better than 86dB sensitivity of the box to push. The problem is that sensitivity testing is sent to the entire speaker can sound pressure testing, rather than for individual tests on each unit. So, when the input power 100W speakers (assuming a three-way speaker), first met divider, divider, after eating some of the power, then the rest of the power delivered to the three units. At this point the efficiency of the three units will be different because of their own, different impedance curve of the power input produce different reactions. In other words, high, medium, given the volume of the woofer is not as big. The usual experience is that a small amount of sense if the bass will find it hard to push this pair of speakers, whether it is in the manual on how high the nominal sensitivity, it is difficult to push.
offset phase angle is a more technical-oriented topics, it is difficult to use a simple analogy clearly popular. As long as we can remember the conclusion: the phase angle shift is also an aspect of speaker impedance (the other aspect is the magnitude of impedance, we usually say that the resistance, in fact, refers to the impedance magnitude.)
phase angle shift the greater the deviation from the pure resistance means that the characteristics of speakers farther ahead of the phase angle showed a capacitive load characteristics, characteristics of the phase angle of the inductive load lag. For the amplifier, the most likely to drive purely resistive loads, capacitive or inductive loads are difficult to drive. If you appeared at a frequency of large phase angle shift, while the impedance associated with lower amplitude, so that the load on the amplifier is undoubtedly worse, hard to drive.
final say in the EMF. Loquat speaker assembly can be viewed as a coil, a magnet generators, when the current input of the amplifier in, drive around the diaphragm to the piston movement, cutting the coil speaker unit will produce magnetic field lines induced electromotive force and current, power generation machine is to use this principle to work. This unit current through the feedback circuit will of course back to the amplifier input stage input, interference amplifier work. EMF larger more formidable speaker. Some transistor amplifier uses no negative feedback loop designed to reduce the impact of EMF.
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