Production of an "earth cannon" sound

This article starts with the power amplifier, and mails the NE5532 for the pre-stage and the TDA1521 Suzhou kit (with transformer) for the post-stage at Hangzhou Xile Electrical Appliances. The speaker is a Guangzhou Kodak speaker sold by Gaojia as a wooden shell. Four of the woofers are damaged, two midrange and two treble are good, and are equipped with a crossover. Four southern whale 6.5 inch bass Put on.

The audio source uses the existing recorder. During the audition, it was found that the sound strength and resolution are quite good when receiving FM stereo broadcasting, but the tape is not satisfactory, and there is distortion when the volume is turned up. The reason for analysis is: FM stereo broadcasting The range is better than magnetic tape, and because the front and back power supplies of the amplifier share a transformer, the power reserve is not enough (25W). Therefore, it was decided to add a transformer, find a 200W iron core and wind a transformer to supply power to the subsequent stage separately. The secondary wire is thicker and the internal resistance is reduced. After that, the dynamic expander was bulk-packed by mail order from Guilin Shida Technology Service Company, and it was refreshing to listen to it after assembly. The effect of playing the tape is as described in the introduction of the dynamic expander: the entire sound field is extended, the stereo level expressed by the high and midrange is more obvious, the bass is magnificent, and the power is fluctuating. "Yan Forest Story Ballroom Dance" is heart-wrenching. With a friend MD911 laser player as the sound source, its sound is more beautiful and beautiful. The circuit principle is shown in the figure.

In order to decorate its appearance, referring to the article "Light-Emitting Diode Level Meter" introduced by "Radio" magazine, five left and right 2 * 5 red LED level displays were made, and finally reminded the friends of the production that the transformer secondary voltage Do not exceed 2 * 14V. As shown in the figure, only half of the circuit of the whole machine is given, and the other half is exactly the same, for reference only. RP1 controls the expansion amount, RP2 controls the volume, and adjusts RP3 to emit 5 LEDs at maximum output.