Build a 170W Bridge Power Amplifier with TDA7294 IC

170W Bridge Amplifier using TDA7294 IC + PCB

🌐 You can read this article in: Português | Español

💡 Expert Tip: This project is ideal for anyone seeking a high-power amplifier with excellent sound quality for home audio systems, small events, or home recording studios.

Hello, electronics enthusiasts!

Today we present a Class AB Audio Power Amplifier that uses two TDA7294 Integrated Circuits in Bridge configuration to drive one or more high-power speakers.

This circuit provides a total output power of 170W, with excellent sound quality, powered by a symmetrical power supply. Imagine the power needed to liven up a small party or to provide an immersive audio experience in your living room – that’s exactly what this amplifier can offer!

The Amplifier responds exceptionally well to all audible frequency ranges, and has a minimalist and compact design, which makes this amplifier an excellent choice for an unprecedented range of applications, from home sound systems to small recording studios.

🎯 Main advantages of this project:

High power with relatively simple components
Excellent sound quality with low distortion
Integrated thermal and short-circuit protection
Compact design ideal for space-limited applications

📒 Description of the TDA7294 Integrated Circuit

The TDA7294 is a monolithic integrated circuit in Multiwatt15 package, designed for use as a class AB audio amplifier in High Fidelity (Hi-Fi) applications, such as home audio systems, active speakers, guitar amplifiers and high-quality TVs.

Thanks to its wide voltage range and high output current capability, it can deliver the highest power into 4Ω and 8Ω loads, even in the presence of poor power supply regulation, with high Power Supply Rejection Ratio.

The built-in muting function with turn-on delay simplifies remote operation, avoiding turn-on/off noises. Think of this as a “soft start” for your amplifier, protecting both the components and your speakers.

🔍 For the curious: What makes the TDA7294 special?

The TDA7294 combines DMOS (double-diffused MOSFET) technology in the output stage with bipolar circuits in the input stages, resulting in a chip that offers the best of both worlds: the linearity of bipolar transistors and the efficiency of MOSFETs. That’s why this IC is so valued in high-quality audio projects!

💡 Main Advantages of Bridge Configuration

The bridge configuration is like having two amplifiers working in team to double the available power. Instead of each amplifier working with a ground reference, they operate in phase opposition, essentially “pushing and pulling” the speaker simultaneously. The result? Significantly more power without needing to increase the power supply voltage!

High power performance with limited power supply voltage level.
Considerably high output power, even with high load values (i.e., 16 Ohm).
For an 8Ω Speaker, with Vs = ± 25V, the maximum output power obtained is 150W, while with a 16Ω Speaker, Vs = ± 35V, the maximum power is 170W.

⚡ Analogy to understand the Bridge configuration:

Imagine two pushers on a seesaw. Instead of just one pushing (simple configuration), both push simultaneously in opposite directions, effectively doubling the applied force. That’s exactly what the Bridge configuration does with the audio signal!

⚙️ Technical Specifications

Operating Voltage Range (± 10V to ±40V)
DMOS Output Stage
High Output Power (Up to 100W musical)
Mute / Stand-By Functions
No Turn-On/Off Noise
No Boucherot Cells
Very Low Distortion
Very Low Noise
Short-circuit protection
Thermal shutdown

📊 Performance comparison:

Configuration	Impedance	Voltage	Power
Single TDA7294	8Ω	±25V	70W
Bridge (2x TDA7294)	8Ω	±25V	150W
Bridge (2x TDA7294)	16Ω	±35V	170W

🔅 Application in Bridge Configuration

Our amplifier is configured in Bridge mode, where two TDA7294 ICs are used. With this type of configuration, we obtain a significant power of 170W, however, there are two different configurations:

For 8Ω Speaker – Vs = ± 25V, the maximum output power is 150W.
For 16Ω Speaker – Vs = ± 35V, the maximum power is 170W.

We know that the TDA7294 supports 4Ω or 8Ω speakers in mono version, however, for this application in Bridge configuration, the speaker impedance should not be lower than 8Ω for reasons of dissipation and current conduction capability of the Integrated Circuits.

⚠️ Important warning:

Never use speakers with impedance lower than 8Ω in this Bridge configuration! This can overload the TDA7294 ICs, causing overheating and possible permanent damage to the components.

🔌 Electrical Schematic

In Figure 2 below, we have the arrangement of the amplifier circuit components with the two TDA7294 ICs. As we can see, the complexity is not extreme.

Since there are few external components, the assembly of the amplifier circuit is very simple, and a technician or hobbyist with average experience can assemble it without much difficulty.

It is important to be careful when assembling the circuit, not inverting any component such as diodes or capacitors, or even when connecting the symmetrical voltage of the power supply.

Do not invert voltage poles, as the integrated circuit or other components may be damaged.

Fig. 2 – 170W Bridge Amplifier Circuit Schematic with TDA7294 IC

🔍 Schematic analysis:

The schematic shows two TDA7294 ICs configured in bridge. The first IC (U1) functions as a non-inverting amplifier, while the second (U2) operates as an inverting amplifier. This configuration creates opposite audio signals that are applied to both ends of the speaker, effectively doubling the voltage across it and, consequently, quadrupling the power (P = V²/R).

📚 You might also be interested in:

🧾 Bill of Materials

Semiconductors

U1, U2 …………………… TDA7294 Integrated Circuit
D1 …………………………. 1N4148 Silicon Diode

Resistors

R1, R5, R6, R8, R10 … 22K Resistor (red, red, orange, gold)
R2 ………………………….. 20K Resistor (red, black, orange, gold)
R3 ………………………….. 10K Resistor (brown, black, orange, gold)
R4 ………………………….. 30K Resistor (orange, black, orange, gold)
R7, R9 ……………………. 680Ω Resistor (blue, gray, black, gold)

Capacitors

C1, C4 ……………………. 1μF Ceramic/Polyester Capacitor
C2, C3, C5, C6 ………… 22μF Electrolytic Capacitor

Others

P1, P2 ……………………. 5mm 2-Pin Screw Connector
P3 ………………………….. 5mm 3-Pin Screw Connector
J1 ……………………………3-Pin Male Connector Set (Optional)
Other ……………………… PCB, Wires, Speaker, etc.

💡 Assembly tips:

Use good quality solder to ensure reliable connections
Check polarity of electrolytic capacitors before soldering
Consider using sockets for the TDA7294 ICs to facilitate possible replacements
Test circuit with reduced voltage before applying full voltage

⚡ Power Supply

The power supply will depend on which output power you choose, which will also depend on how many Ohms your speaker will have. We have two versions:

Version 1 – 150W Output.

Speaker should be 8Ω and the maximum voltage is ±25V

Version 2 – 170W Output.

Speaker should be 16Ω and the maximum voltage is ±35V.

Remember that for both versions a symmetrical power supply is used, i.e., [ +VCC | GND | -VCC ]. With a current of at least 6 Amperes.

🔧 Power supply recommendations:

To get the best performance from this amplifier, we recommend a power supply with good regulation and low ripple. Silicon steel core transformers and high-quality filter capacitors will make a noticeable difference in the final sound quality. Consider adding decoupling capacitors near the ICs to improve high-frequency response.

🖨️ Printed Circuit Board (PCB)

In Figure 4, we provide the PCB – Printed Circuit Board, in GERBER, PDF and PNG files. These files are available for free download, on the MEGA server, in a direct link, without any detour.

Everything to facilitate a more optimized assembly for you, whether at home, or with a company that prints the board. You can download the files in the Download option below.

Fig. 4 – PCB of 170W Bridge Amplifier using TDA7294 IC

🔧 PCB manufacturing tips:

For better heat dissipation, consider using a PCB with thick copper (35μm or more)
If possible, add additional copper areas under the ICs to help with thermal dissipation
Check if the power traces are wide enough to support the required current
Consider adding mounting holes near the ICs to facilitate the installation of heat sinks

📥 Download files, Direct Link:

Click on the link next to it: GERBER, PDF and PNG files

❓ Frequently Asked Questions

Find answers to common questions about this amplifier circuit below.

Can I use this amplifier with 4Ω speakers? 🔽

We don’t recommend it. This Bridge configuration was designed to work with a minimum impedance of 8Ω. Using 4Ω speakers can overload the ICs, causing overheating and possible permanent damage.

Is it necessary to use heat sinks on the TDA7294 ICs? 🔽

Yes, absolutely! The TDA7294 ICs dissipate significant heat during operation, especially at high powers. We recommend using adequate heat sinks for each IC, with sufficient area to keep the temperature below 80°C.

Can I convert this amplifier into a stereo system? 🔽

To create a stereo system, you would need to build two circuits identical to this one, one for each channel. Alternatively, you could configure each TDA7294 individually (instead of in bridge) to create two lower power channels.

What is the expected sound quality of this amplifier? 🔽

The TDA7294 is known for its excellent sound quality, with low harmonic distortion (typically less than 0.1%) and low noise. You can expect a clean and detailed sound, suitable for high-fidelity audio applications.

Is this amplifier suitable for guitars or musical instruments? 🔽

Yes, this amplifier works very well for guitars and other musical instruments. Its high power and low distortion provide a clean and dynamic sound. For guitar applications, you may want to add a preamplifier circuit or effects before this power stage.

🎯 Tips to get the best performance:

Use good quality wires for audio and power connections
Position the ICs as close as possible to the decoupling capacitors
Consider adding a fan to improve cooling during continuous use
Use a Faraday cage or proper shielding if there is RF interference

✨ Our Gratitude and Next Steps

We sincerely hope this guide has been useful and enriching for your projects! Thank you for dedicating your time to this content.

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Best regards,
The ElCircuits Team ⚡