When to select pure rear power amplifier


Insiders have always been very clear that the rear part of the combined power amplifier below 10000 yuan is not worth considering, especially the new combined power amplifier, which has seriously shrunk and falsely reported power, but has been extended to all combined power amplifiers.

In fact, many years ago, there was no such thing as cutting corners and falsely reporting power. Now I find that the Jianghu is not what it used to be, and it is full of commercial deception. Many years ago, a small flagship power amplifier of tens of thousands of yuan was changed to pure, 60W × 3+22W × 4. Use HTPC + D2 to push 7 large boxes to make them taste delicious!. In the absence of subwoofer, we all feel strong sofa * *. On the contrary, today, in so many audio forums, we talk about "unable to push", and many manufacturers are 100-200W × 7's nominal power, but there is still the saying that it can't be pushed, which makes me depressed and incomprehensible. I don't want to analyze why manufacturers do this anymore. After the power amplifier, it uses a lot of copper and aluminum! As long as people are a little older, they should know that copper and aluminum were just a little more expensive than iron in the past and were worthless. Ordinary people have copper everywhere, but what about today?

Many friends don't quite understand what kind of performance the power amplifier really wants to achieve. They mistakenly think that as long as the power is large enough, it is king. They don't know the difference between the combined power amplifier and the pure power amplifier. Those friends want "control power" and "analytical power" to speak and shut up, but they don't know how the power amplifier can achieve these properties.

A friend once consulted me about a 2-channel pure, and I put forward two key concepts, namely "damping coefficient" and "conversion rate", which are not familiar to everyone.

Basic index of power amplifier: rated power.

Today, power amplifiers in the United States and Europe will be marked with rated power. The old power amplifier is also marked with rated power. Generally, the power is measured when the distortion is very small (for example, the power measured at 0.015%, 20-20KHz, and the power amplifier is measured at 0.008%).

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

The above has shown that this is directly related to the power. When the power of the power amplifier is large enough and only a small part of its power is used, the distortion will be much smaller.

Combined power amplifiers often only use a pair of power tubes, and the pairing of power tubes has a great impact on the distortion, In the past, high power amplifiers were paired directly to the device production line (for example, the distortion of the old power amplifier is very small. The 10000 yuan in those years is equivalent to 100000 yuan today). The cost is very high. Today's power amplifiers with less than tens of thousands of yuan will not do this. Today, with poor matching of power tubes, it is even more necessary to reduce the distortion with its small power under high power. The distortion reflects the quality of sound, that is, texture.

An important index of high power amplifier: damping coefficient.

In addition to power and distortion, the internal resistance of a high power amplifier has a great relationship with the control ability of bass quality. In order to ensure a small output impedance in high current environment, high-quality high-power transformer, high-current rectifier circuit and powerful capacitor filter circuit are first necessary. No matter how high these things are, the combined power amplifier will never have them due to the limitations of space and cost. The pure power amplifier is several times higher than the combined power amplifier in this regard. Secondly, in order to achieve strong output power and very small transistor output impedance, the pure power amplifier uses several pairs of power tubes to work in parallel, and its control force is several times stronger than the combined power amplifier, while the combined power amplifier only uses a pair of output power tubes (see how many pairs of power tubes can be installed in such a small radiator?).

Of course, the thickness of horn wire, copper content and the quality of terminal also have a direct impact on the damping coefficient. The damping coefficient reflects the control quality of the power amplifier to the bass, that is, the control force.