Sunday, March 28, 2010

Headphone Amplifier with LM833

This is a headphone amplifier circuit based on IC LM833 or NE5532 supporter with 4 transistors (one channel). The input can be directly connected to audio devices such as MP3/MP4 player, CD/DVD plater, radio or computer.

4 Transistors Headphone Amplifier with LM833 circuit diagram

Amplifier part list:
P1 __________ 22K Log.Potentiometer (Dual-gang for stereo)
R1 __________ 560R
R2,R3 _______ 10K
R4 __________ 12K
R5,R6 _______ 2R2
R7 __________ 22R
C1 __________ 1uF/63V
C2,C3,C4 ____ 100uF/25V
C5 __________ 22pF/63V
C6 __________ 22uF/25V
IC1 _________ LM833 or NE5532
Q1,Q3 _______ BC337 45V 800mA NPN Transistors
Q2,Q4 _______ BC327 45V 800mA PNP Transistors
J1 __________ RCA audio input socket

Power supply part list:
R7 __________ 2K2
C7,C8 _______ 2200uF/25V
D1 __________ 100V 1A Diode bridge
D2 __________ 5mm. or 3mm. Red LED
IC2 _________ 7815 15V 1A Positive voltage regulator IC
IC3 _________ 7915 15V 1A Negative voltage regulator IC
T1 __________ 220V Primary, 15 + 15V Secondary 5VA Mains transformer
PL1 _________ Male Mains plug
SW1 _________ SPST Mains switch

Technical data:
  • Output voltage: Well above 5V RMS on all loads
  • Sensitivity: 250mV input for 5V RMS output
  • Frequency response: Flat from 30Hz to 20KHz
  • Total harmonic distortion @ 1KHz & 10KHz: Below 0.005% on 32 Ohms load and up to 4V RMS output (typical 0.003%)
  • Total harmonic distortion @ 1KHz & 10KHz: Below 0.005% on 100 to 2000 Ohms load and up to 5V RMS output (typical 0.003%)

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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