Cheng Op Amp and Ji Cong Amp are two types of devices that junior enthusiasts and student enthusiasts like to use. They have many varieties, different performances, and different sound quality and timbre. How to match and combine the above two types of devices in order to make the best use of their respective advantages, give full play to their respective advantages, and create a priority price-performance ratio is a question worth discussing. 　　Although the author has accumulated some experience in the fever course for several years, he also stocks a considerable number of audio devices. Among them, there are many integrated operational amplifiers and integrated successful amplifiers, including the early fever op amps LM833N, NE5532N, NE5535N and the recently popular OP275G, LT1057, AD827JN. Jisongfang is some well-known models, such as TDA1514A, LM1875T, LM1876TF, LM3886TF and the early TA2030A. Of course, the integrated blocks such as JRC4558P, TL072, and TDA2030, because their performance is not enough to "fever" level, there is no need to come up with research. 　　 The above collections are all ready-made finished boards. The components and craftsmanship on the boards are still more elaborate and are very simple. For the above-mentioned op amps, because they are standard dual op amps, only one pre-buffer amplifier board is used, which is the one used for AD827 in "Fine Item 1876" in "Electronic News" on June 13, 1999. . The components are very sophisticated: DALE W gold film resistors, WIMA, ELNA capacitors, APLS potentiometers, silver-plated double panels, and the technology is also very sophisticated. The author removed the AD827 and replaced it with a 24K gold-plated op amp socket.

The MLX91210 IC is powered by a 5V power supply, the current sensitivity level is as low as 26.7mV/A, and supports a large ±75A, linear current measurement range equivalent to 30ARMS current. This fully integrated Hall effect current sensor is available in SO8 and SO16 packages, with very low resistance loss (SO8 is 0.8mΩ, SO16 is 0.7mΩ), and provides high voltage isolation levels (2.1kVRMS and 2.5KVRMS, respectively), And faster response (only within 5us). The sensor outputs of all ICs are factory calibrated for a specific current range, and compensated for the temperature-related, better stability during their operating life, thereby maintaining long-term accuracy.

Nearly 80% of my country's land is well lit, and the distribution of solar energy resources is relatively even. Compared with hydropower, wind power and nuclear power, solar power generation does not have any emissions and noise, and its application technology is relatively mature. It does not require any "fuel" except for sunshine. In terms of site selection, in addition to large-scale grid-connected power generation and off-grid applications, solar energy can also be stored in various ways such as pumping, superconductivity, storage batteries, and hydrogen production.

The insiders have always been very clear that the post-stage part of the combined power amplifier below 10,000 yuan is not worth considering. Especially for the new combined power amplifier, the post-stage is seriously shrunk and the power is falsely reported, but it is extended to all the combined power amplifiers. In fact, there was no such thing as cutting corners and falsely reporting power many years ago. It is now found that the rivers and lakes are not what they used to be, and commercial fraud is everywhere. A small flagship power amplifier with a value of tens of thousands of years ago was changed to a pure post-level, 60W×3+22W×4, and HTPC+D2 was used to push 7 large boxes to taste! . In the absence of a subwoofer, I feel a strong sofa**. In contrast, today, in so many audio forums, what I talk about is “can’t push”, and many manufacturers keep the standard of 100-200W×7. Power, but there is still no way to push it, which keeps me depressed and incomprehensible. I will no longer analyze why the manufacturer should do this. The post-amplifier is to use a lot of copper and aluminum! Anyone who is a little older should know that copper and aluminum were just a little more expensive than iron before, and they are not valuable. Ordinary people have bronzes everywhere, but what about today?