This is a Tri audio amplifier circuit. Why it is interesting?
Imagine, how well do we know. If you hear the music of the full frequency band in our cheap audio system.
This project maybe great answer.
The tri audio amplifier has three in one a amplification act drive specifically each audio speakers. It makes the sound quality is very good.
In Normal amplifier can drive three speakers at the same time are the woofer, mid-range and tweeter. Which may have limits. For example: the impedance of the speakers, the loss of signal in Crossover Network. But it’s very expensive.
Thus, when compared to the same quality and power of these amplifier and crossover network. They will have the price more than this the Tri audio amplifier circuit.
When viewing the various elements, then are seen as better in every aspect.
Although there are not a lot of power. But it’s only for listening in your home or bedroom very well.
Some people are interested in the efficiency of this circuit. See in the graph below.
We will see that it can respond to the sound frequency well. Covering almost all frequency bands
You probably got the answer. Are you ready?
The working principles
Look at the below.
It is a block diagram of tri audio amplifier circuit. It will split the audio frequency range into 3 ranges:
- Cut off at 300Hz for low frequency range.
- Then cut off at 3 KHz for midrange.
- And the frequency exceeds 3KHz is the high frequency.
Then the signal is sent to each audio amplifier circuits. To drive each speaker the woofer, midrange and tweeter immediately.
What is more? see circuit!
How this circuit works
Look at the complete circuit diagram below.
Although many devices. But probably easy. If gradually understanding it. Here is step by step a process.
Recommended: TDA2030 Audio Amplifier Circuits
The Woofer or Bass sound
The resistor R1 will be connected between input and ground. To control input signal does not too much. And makes a constant impedance input.
The C1 act as coupling the input signal to a low pass filter circuit.
Which they consists of R3, R4, C2 and C3. The signal that through this filter circuit will be low frequency under 300 Hz only.
Then, this signal comes to input of IC1(TDA2030) to amplify. To the drive transistor Q1 and Q2. They increase the audio up.
And Both resistors R7 and R8 are biased to Q1(BD239) and Q2(BD240).
The resistor-R6 is feedback. And both C4 and R5 are divider the feedback voltage too.
Both R9 and C9 are load for this section circuit. The capacitor C8 act as coupling output signal to drive the woofer speaker.
Read Also: TDA2030 transistor amp circuit with PCB
The MidRange Sound
The middle sound frequency are about 300Hz – 3KHz. It will pass the mid rang filter circuit.
Which they consists of C10,C11,C12 and R10,R11,C12,C13. Both is filter 2 step in series together.
Then, this signal comes to the input of IC2. To increase the power up.
The R15 is the feedback. And R14,C14 are the divider feedback.
The R16,C16 are load of circuit.
The C17 act coupling the output signal to the Mid-rang speaker.
What is more? See!
The Tweeter or Treble sound
And in high frequency range that exceeds 3 KHz. It will pass the high pass filter circuit. They comprises C18,C19 and R17.
Then this signal will come to the input of IC3. Which it act as amplifier the signal rise.
The R20 is a feedback. And C20,R19 are divider a feedback voltage. The R21,C21 are loadof circuit.
The C23 act as coupling the output signal to drive Tweeter speaker.
The R22 and R23 are connected as the divider circuit. To separate the voltage to half of the power supply circuit. And C24 maintains the voltage to smooth and constant.
This voltage is a biased the voltage to the input (pin 1) of IC1, IC2 and IC3.
Read next: TDA2030 stereo amplifier circuit
Protection and power supply
And R2, R13 and R18 limit the current is not too much.
Diodes D1-D6 protects the IC from damage from the feedback voltage .
The capacitors C7, C15 and C22 helps eliminate noise from the power supply.
The C6 filter to smooth the power supply circuit. And diode D7 is a diode bridge rectifier of the AC.
Let’s build this circuit
This project is quite easy, since we use popularly components. As shown in PCB layout diagram.
I trust you can make them.
Parts you will need
0.25W Resistors, tolerance: 5%
- R1: 680Ω 0.5 watts
- R2, R3, R4, R10, R11, R18, R22, R23: 22K
- R5, R14, R19: 100Ω
- R6, R12: 3.3K
- R7, R8: 1.5Ω 0.5 watts
- R9, R16, R21: 1Ω 0.5 watts
- R13: 68K
- R15: 2.2K
- R17: 12K
- R22: 4.7K
- C1: 1µF 25V
- C4, C14: 100µF 16V
- C6: 2,200µF 50V
- C17: 220µF 25V
- C20: 47µF 16V
- C23, C24: 100µF 25V
Ceramic or Mylar Capacitors
- C2: 0.033µF 50V
- C3: 0.018µF 50V
- C5, C7, C9, C15, C16, C21, C22: 0.22µF 50V
- C10, C11: 0.1µF 50V
- C18, C19: 0.0033µF 50V
- D1-D6: 1N4001, 50V 1A Diodes
- BD1 or D7: 5A 200V Bridge Diode
- IC1- IC3: TDA2030A
- Q1: BD239, TIP41, 40V 4A NPN Transistor
- Q2: BD240, TIP42, 40V 4A PNP Transistor
T1: 24V to 30V 3A transformer
PCB, Heatsinks, transformer
Here are a few related posts you might want to read:
- LM3875 Gainclone Amplifier circuit | Stereo 56W
- LM1875 Datasheet 30W HIFi audio amplifier circuit
- Cheap car subwoofer filter circuits
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