4W Audio Amplifier Circuit using IC LA4550

LA4550 is dual power amp IC which is used for low sound boost in audio systems.

The circuit is popular in small speaker, radios and audio devices

It is easy to use and is highly efficient.

4W Audio Amplifier Circuit using IC LA4550 gives max 4W power and is good for small audio project.

It has cool features like:

• It uses very low power when idle.
• It has two channel: stereo or bridge mode.
• It reduces noise from power change.
• And keeps left/right sound clear.
• There is no click noise on power ON/OFF

Circuit Working:

Parts List:

This is one channel audio amp using LA4550 IC.

It work on 12V DC and powers 8 ohm speaker with 4W sound.

Audio goes in pin 4 through capacitor C4.

C4 block DC and only lets audio pass.

IC boost weak audio inside.

C2 and R1 help with feedback and keep circuit stable.

Gain set by IC design which can be changed with feedback parts.

C1, C3, C11 keep power clean and reduces noise.

Boosted audio go to speaker through C9.

C9 block DC and send only audio to speaker.

Speaker change audio signal to sound.

Formulas with Calculations:

Formulas with example for 4W Audio Amp using LA4550:

Output Power:

P = V² / R

where,

• P is the power in watt
• V is the peak voltage from power supply
• R is the speaker resistance

Example:

12V supply with 8 ohm speaker:

P = 12² / 8 = 144 / 8 = 4W

Capacitor Select:

fc = 1 / (2πRC)

where,

• fc is the cutoff frequency
• R is the 8 ohm speaker
• C is the capacitor value

Example:

fc = 20Hz:

C = 1 / (2π × 8 × 20) = 0.99 µF

Power Loss (Dissipation):

PDISS = VCC × IQ

where,

• VCC is the supply voltage
• IQ is the idle current from IC datasheet

How to Build:

To build a 4W Audio Amplifier Circuit using IC LA4550 following are the connections steps to follow:

• Get all parts from circuit diagram.
• Pin 2 of LA4550 connects one end of 8Ω speaker through cap C10.
• Pin 2 connects pin 3 through capacitor C3.
• Pin 4 connects pin 9 through capacitors C3 and C6.
• From pin 4 connects capacitor C5 and resistor R2 to GND.
• Pin 6 connects pin 7 through capacitor C4.
• Pin 8 connects audio input.
• Pin 10 connects pin 11 through capacitor C10.
• Pin 11 connects other end of 8Ω speaker through capacitor C9.
• From pin 11 connect capacitor C8 and resistor R3 to GND.
• Pin 12 connects to +12V DC.
• Capacitor C11 and C12 connects between +12V and GND.

Conclusion:

4W Audio Amplifier Circuit using IC LA4550 is small, simple and good for low power sound.

It is easy to build and its parts are easy to find.

The circuit gives clear sound with low noise.

And is good for small speaker for hobby or for professional use.

By following diagram, doing proper calculations and build as said, we can make working 4W audio amp circuit.

References:

Integrated circuits power audio amplifiers