Simply share some knowledge about tube power amplifiers

Tube amplifiers work under high voltage and low current conditions. The plate voltage of the final power amplifier tube can reach 400-500V or even thousands of volts, while the current flowing through the tube is only tens to hundreds of milliamperes. The input dynamic range is large and the conversion rate is fast.

Most tube amplifiers use discrete components, manual wiring, and welding, which have low efficiency and high cost. This is especially evident in developed countries.

The open-loop index of the tube power amplifier is better than that of the transistor. It does not need deep negative feedback and can work stably without adding a phase compensation capacitor, so its dynamic index is better.

But in addition, the life of the electronic tube is relatively low, and some technical indicators will drop significantly after one or two thousand hours of use. Tube amplifiers consume a lot of power and often work in Class A state, which lowers the efficiency, but there are basically no factors harmful to sound quality such as transient intermodulation distortion, switching distortion, and crossover distortion.

Tube amplifiers are not at all superior to transistor amplifiers in terms of weight, efficiency, lifespan, and power consumption, and their disadvantages are obvious.

Generally speaking, the sound quality of the tube power amplifier is soft and pleasant. More specifically, the low frequency sound of the tube power amplifier is soft and clear, and the high frequency sound is delicate and clean. Expressing vocals is his forte.

In use, the electronic tube must have good ventilation and heat dissipation. Overheating of the temperature will inevitably shorten the life of the electronic tube, so try to keep the temperature of the electronic tube as low as possible.

Electronic tubes are afraid of vibration, so it is also very important to take anti-shock measures to avoid vibration as much as possible. If these two points are achieved, the service life of the electron tube can be doubled at least!

To this end, there should be proper space around the tube equipment, especially above it, so that there is good convection ventilation, and a fan can be used to help dissipate heat if possible.

When the cathode of the electron tube has not reached the required temperature and the high-voltage power supply is applied, its cathode will be damaged, which will also shorten the life of the electron tube. Therefore, if the electronic tube equipment has a preheating device, it must be used!

For example, turn on the filament low-voltage power supply to preheat first, and then turn on the high-voltage power supply. If there is no preheating device, don't rush to connect the input signal, you can turn off the volume to the minimum, and wait for 20 to 30 minutes to warm up before using it.

If the side heating rectifier is used to supply the high voltage of the whole machine, it just provides a simple and effective high voltage delay. In addition, during normal use, do not switch the power on and off frequently!