Sunday, August 23, 2009

Pre-amp circuit with tone control

Pre-amp circuit with tone control

This a 2 in 1 circuit where 2 modules joined in one circuit. With this circuit, you no longer use tone control circuit before your amplifier, but you can add an equalizer between this circuit and your amplifier circuit. In this circuit, P1 is used to control the volume level, P2 to control Bass level and P3 controls Treble level.

This is a mono channel circuit, you need to build another equal circuit to make this circuit has stereo channel.

Part List:

R1__________220K 1/4W Resistor
R2__________100K 1/4W Resistor
R3__________2K7 1/4W Resistor
R4,R5_______8K2 1/4W Resistors
R6__________4K7 1/4W Resistor
R7,R8,R13___2K2 1/4W Resistors
R9__________2M2 1/4W Resistor
R10,R11_____47K 1/4W Resistor
R12_________33K 1/4W Resistor
R14_________470R 1/4W Resistor
R15_________10K 1/4W Resistor
R16_________3K3 1/4W Resistor (See Notes)

C1,C2,C9____470nF 63V Polyester Capacitors
C3,C4_______47nF 63V Polyester Capacitors
C5,C6_______6n8 63V Polyester Capacitors
C7__________10µF 63V Electrolytic Capacitor
C8,C10______22µF 25V Electrolytic Capacitors
C11_________470µF 25V Electrolytic Capacitor

Q1,Q3_______BC550C 45V 100mA Low noise High gain NPN Transistors
Q2__________2N3819 General-purpose N-Channel FET

About Audio Amplifier
An audio amplifier is an electronic amplifier that amplifies low-power audio signals (signals composed primarily of frequencies between 20 - 20 000 Hz, the human range of hearing) to a level suitable for driving loudspeakers and is the final stage in a typical audio playback chain.

The preceding stages in such a chain are low power audio amplifiers which perform tasks like pre-amplification, equalization, tone control, mixing/effects, or audio sources like record players, CD players, and cassette players. Most audio amplifiers require these low-level inputs to adhere to line levels.

While the input signal to an audio amplifier may measure only a few hundred microwatts, its output may be tens, hundreds, or thousands of watts. More explanation about power audio amplifier can be found at

This is a video tutorial about how to a very simple audio amplifier based on the LM386 amplifier chip. It can be built for less than $20 (or might be less than $8 in some countries) and used to amplify any low level audio signal including a guitar, bass or mp3 player.

Watch the video:

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