• WARNING: Tube/Valve amplifiers use potentially LETHAL HIGH VOLTAGES.
    Building, troubleshooting and testing of these amplifiers should only be
    performed by someone who is thoroughly familiar with
    the safety precautions around high voltages.

EC88 dirver PL84 push-pull,DIY with a picture tells a story.


PL84, it is 15v of EL86, compare EL84, has a lower resistance, gifted audio born. Single-ended output is about 5w, push-pull is up to 17.5w. It can be described as a small tube big power.
First test is the level hum of the machine. Amateur environmental manufacturing, has 0.7mv hum. From the size point of view, it is not very good, from the frequency analysis, the hum from the power supply filtering. 350uf electrolytic capacitor two, there is no power filter choke hum 0.7mV100Hz bring to final output, from a practical point of view, this is already small enough. 93db sensitivity JBL4425 ear does not hear.

Distortion level whole wide for everyone concerned, the following figure provides spectrum analysis data output is 1v time.

Seen from the figure, the second harmonic distortion -60.253db about 0.095%

Third harmonic distortion -67.138db about 0.03%

Distortion far below the level hum.

The first hole machining is completed. It takes approximately 4-5 minutes. Everything is in accordance with a pre-set program automatically. The whole process takes approximately 4-5 hours. Until this side completely finished processing.