When to select a pure after - stage power amplifier


The people in the bank have been very clear that the post-stage part of the combined power amplifier below 10,000 yuan is not worth considering, especially the newly emerged combined power amplifier, the post-stage is seriously shrunk, and the false power is expanded to all the combined power amplifier.

Actually, many years ago did not have this kind of cut - and - drop, false report power matter. Now we find that the rivers and lakes are not what they used to be. Many years ago, a small flagship power amplifier worth tens of thousands of yuan was changed to pure post-class, 60W x 3+22W x 4, with HTPC+D2, pushing 7 big boxes with youziyouwei! . In the absence of subwoofer, I felt the strong sofa **. Today, on so many stereo BBS, we talked about "push not move". Many manufacturers are always on the 100-200w x 7 nominal power, but there are still push not move said, I have been depressed, unable to understand. I no longer analyze why the manufacturers do this, the power amplifier after the level is to use a lot of copper and aluminum! As long as a little old people should know, copper and aluminum in the past just a little more expensive than iron, is not valuable, ordinary people everywhere have copper ware, but today?

Many friends do not know what kind of performance the amplifier really wants to achieve. They mistakenly believe that power is the king as long as the power is big enough, and they have no idea of the difference between the latter and the former of the combined amplifier. Those friends who keep their mouth shut are those who want "control", "analytical power", etc., but don't know how the amplifier can achieve these performances.

A friend once consulted me on a 2-channel pure back stage, and I proposed two key concepts, "damping coefficient" and "conversion rate".

Basic index of amplifier: rated power.

American and European amplifiers are now marked with rated power. The old amplifier is also labeled with rated power. Generally, the power is measured at low distortion (such as 0.015%, 20-20khz power, and 0.008% power of higher power amplifier). To have strong output power, strong power supply support is absolutely necessary! The size of the power reflects the intensity of the sound, namely the sense of quantity.

The second basic index of power amplifier: various distortion degree.

As indicated above, this is directly related to the size of power. When the power of the amplifier is large enough and only a fraction of the power is used, the distortion is much smaller.

Level after the merger amplifier is often just use a pair of power tube, power tube of matching has much effect on the degree of distortion, high power amplifier is directly to the device of the production line matching (old power amplifier distortion is very small, for example, the ten thousand yuan to the equivalent of today's one hundred thousand yuan), the cost is very high, now tens of thousands of yuan within the power amplifier is not like this. In today's poor power tube pairing, it is more necessary to use the low power to reduce distortion at high power. The degree of distortion reflects the quality of sound, or texture.

The important index of advanced power amplifier: damping coefficient.

In addition to power and distortion, the output resistance of an advanced amplifier has a great impact on the control ability of bass quality. To ensure a small output electrical impedance in a high-current environment, a high quality power transformer, a large current rectifier circuit and a powerful capacitive filter circuit are required first. These things are no more advanced integrated amplifiers due to space and cost constraints. In this respect, the pure post amplifier is several times that of the combined amplifier. Secondly, in order to achieve a powerful power output and tiny transistor output impedance, pure level after the power amplifier is adopted the number of power tube to parallel operation, the control also want to several times stronger than the combined type power amplifier, and combined type power amplifier in a pair of output power tube (see so little of power tube radiator can hold on?) .

Of course, the thickness of the horn line, copper content and the quality of the terminal, also has a direct impact on the damping coefficient. The damping coefficient reflects the quality of the power amplifier's control over the bass.