3 Transistor Headphone Amplifier Circuit | Class AB

It is annoying. The headphones sound very quiet. And cannot hear clearly too. This problem will enable self-improvement. If you take action to solve problems by creating the simple transistor headphone amplifier circuit.

Although this circuit is very old. But I believe that it is your teacher and friend, certainly good music.

The highlight of this circuit is the use of transistor And ordinary equipment, easy to find, and cheap. And, the designer has defined this circuit as Class AB and OTL amplifier model too.

Transistor headphone amplifier circuit

How does the circuit work

This circuit uses the principle of three transistor audio amplifier circuits. Which the first transistor is the preamplifier circuit and the next two transistors are the complementary transistor mode.

They will have an impedance of the circuit be about 500 ohms and have the gain rate of 5 times. It deliveries output power about 50 mW.

Transistor Headphone Amplifier Circuit

Here is step by step a process.

When entering 9 volts power supply (battery) to supply the circuit. Then, put the input signal comes in. The C1 passes the coupling signal and goes to reach base pin (B) of Q1.

Next, the Q1 will increase a signal that gives the power to go up in a leveler. To drive Q2 and Q3 work enlarges current get more and more.

Both Q2 and Q3 work together in the model complementary model. By have R5 and R6 to keep the stability of the current.

After that, a signal output passes C2 to the output to a headphone of impedance 8 ohms to 32 ohms.

And some signal is fed get back via R1, come to reach input at base pin (B) of Q1 to improve good stability circuit.

Disadvantages of this circuit

Due to this circuit, The designer set it in class AB and OTL amplifier. It, therefore, has signal distortion. And a poor response to low-frequency ranges.

If you are a golden ear music player or someone interested in a better circuit. Even if using a more difficult circuit
You should choose this circuit:

Parts you will need

0.25W Resistors, tolerance: 5%

  • R1: 5.6K
  • R2: 1.5K
  • R3: 1K
  • R4: 22Ω
  • R5, R6: 3.3K
  • VR1: Potentiometer Volume 10KA

Electrolytic Capacitors

  • C1: 47uF 16V
  • C2: 220uF 16V
  • C3: 100uF 16V

Semiconductor and other

  • Q1: 2N3904, 45V 0.1A, NPN Transistor
  • Q1: C9013, 40V 0.8A NPN transistor
  • Q3: C9012, 40V 0.8A, PNP transistor
  • D1,D2: 1N4148, 75V 150mA Diodes
  • B1: 9V battery

Not only that, sometimes good ideas may not have one. See below.

Three Transistor Headphone Amplifier – Class AB

Transistor Headphone Amplifier circuit using BC109

Headphone Amplifier using Transistor-BC109

Here is a classic Headphone Amplifier. Because the important part of the circuit is Transistor BC109.

Here are a few related Circuits you may want to learn:

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Gideon Rainstorm

can i conect to it an 0.5W , 8 ohm speaker ? it will be ok ?


Hello I need to design a headphone amplifier to the following spec. I am quite new to electronics and was wondering if you would help me with this. I like your designs but have certain criteria I must meet. I want to use transistors so it forces me to learn about the components and how they work. I am just unsure where to start while meeting the spec. The specification of the amplifier is that it should: • Provide an improved sound quality over the un-amplified output of your MP3 player. • Have an input impedance of at least 100kΩ.… Read more »


Hi,Gideon Rainstorm
Thanks for your feedback.
Yes you can but low sound output. This circuit is used for a headphone.


Hi, Damian

Thanks for your visits now I not have new circuit about Hi-end headphone amplifier.
But in the future I will present these circuits again. Please Subscribe

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