Subwoofer Amplifier Circuit using IC TDA7294 is to boost low bass sound for subwoofer speaker.
The IC is an audio amplifier chip.
TDA7294 is one-chip IC in multiwatt 15 package.
It is good for powered speakers, home stereo and big TVs.
It work as class AB amplifier for Hi-Fi sound.
Circuit Working:
Parts List:
| Category | Item | Quantity |
|---|---|---|
| Resistors (All resistors are 1/4 watt unless specified) | 22k | 3 |
| 680Ω | 1 | |
| 10k | 1 | |
| 2.7Ω | 1 | |
| Capacitors | Ceramic 100nF | 3 |
| Ceramic 470nF | 1 | |
| Electrolytic 22μF 25V | 2 | |
| Electrolytic 10μF 25V | 2 | |
| Electrolytic 1000μF 25V | 2 | |
| Semiconductors | IC TDA7294 | 1 |
| ON/OFF Switch | 2 | |
| 8Ω 150 watt subwoofer speaker | 1 |
Use 150W subwoofer speaker with 8 ohm for best sound.
If only have 30V capacitors then use them, 50V is better but 30V okay.
Higher voltage capacitors work better and last longer.
Pins Vm and Vstby are for extra features.
No need? Just leave them not connected.
Be sure no voltage goes to those pins.
Send music signal to non-inverting input pin of TDA7294.
For volume control put 10k ohm variable resistor between input pin and music source.
This circuit is easy to make on breadboard.
After building give it power with dual 30V power supply.
Formulas:
When making subwoofer amp with TDA7294 we should think about heat, speaker ohm, power supply and gain.
Need these parts and formulas:
Gain Calculation:
Gain changes with feedback resistors.
Use formula:
Gain(dB) = 20 × log10(Rf / Rin)
where,
- Rf is the feedback resistor
- Rin is the input resistor
Output Power Calculation:
Use formula:
Pout = (Vpeak)² / 2R
where,
- R is the speaker impedance with 8 ohm
- Vpeak is the voltage across speaker
Follow this information to build subwoofer amp with TDA7294.
Change parts as needed.
How to Build:
To build a Subwoofer Amplifier Circuit using IC TDA7294 below mentioned are the steps for connections:
- Get all parts like shown in circuit diagram.
- Pin 1 of IC1 connects to ground.
- Pin 2 of IC1 connects to ground with capacitor C2 and resistor R2.
- Pin 3 of IC1 connects to audio input with capacitor C1 and also connect resistor R1 from pin 3 to ground.
- Pin 4 of IC1 connects between ground and resistor R1.
- Pin 6 of IC1 connects to one side of 8Ω speaker and other side of speaker connects to ground.
- Also connect capacitor C5 positive side to pin 6 and negative side to speaker.
- Pin 7 and pin 13 connects to +30V power.
- Pin 8 connects to ground with capacitor C9.
- Pin 9 connect to ON/OFF switch through resistor R4.
- Pin 10 connect to ON/OFF switch through resistor R5.
- Pin 14 connects to pin 2 using resistor R3.
- Pin 15 connects to -30V power.
- Capacitor C4s positive connects to pin 9 and negative to ground.
- Capacitor C3s positive connects to pin 10 and negative to ground.
- Capacitor C8s negative connects to pin 15 and positive connects to ground.
- Capacitors C6s and C7s positive connects to ground.
- Resistor R6 and capacitor C10 connects from pin 6 to ground.
Safety Notes:
- Be careful and do not touch live parts when power is ON as high voltage is dangerous.
- Be sure all wires and joints are insulated well to stop short circuits and fire.
- TDA7294 gets hot so use big heat sink to keep it cool.
- Pick power supply with correct current for our circuit.
Conclusion:
This Subwoofer Amplifier Circuit using IC TDA7294 can give deep bass to our music system.
We should use right parts, keep it cool with heat sink and work in open air place.
If anyone is beginner then try small circuit first as safety is most important.