This is the Preamplifier circuit with a graphic equalizer for the amplifier. This diagram runs on 12 volts. It’s a stereo diagram. Treble, midrange, and bass can be controlled using this board. Every amplifier needs this type of circuit to control the sound quality.

The diagram of this circuit is

Pre-amplifier circuit diagram:
This is a pre-amplifier circuit diagram. Every amplifier needs this type of circuit diagram. This circuit makes the sound good. It has one main volume, a low part, a mid-range part, and a high part. This diagram runs using a 12-volt system only. It’s a mono board/ for stereo needs, a dual board.

This is an Audio amplifier circuit diagram, USA technology. This circuit board can produce 300 watts of output. It’s a mono diagram. A stereo needs a dual circuit board. Here, we can use a 25-0-25 voltage to an 80-0-80 voltage maximum. The best voltage is 50-0-50 volts and 6 amperes. We know that voltage X amperes= watts. So, 50 X 6= 300 watts. Voltage and ampere is the important to get a good output watts.
We can get many amplifier circuit diagrams. This circuit can be used in a 2.1 sound box. We can make a subwoofer amplifier using this diagram. To make a subwoofer, we need a low-pass filter circuit. To get the lowpass filter circuit, please visit here: LOWPASS FILTER. We need this low-pass filter to make a bass amplifier for 2.1 audio. This low-pass filter makes the sound only bass. It’s also a pre-amplifier. We can use this circuit in any amplifier to make a subwoofer amplifier.
Amplifier circuit diagram is here
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