INTRO :-

We have built a Bi-Amp board using TDA7294 Audio Amplifier IC. Bi-Amping is a technique where we have two different amplifier sections, one for woofer (low-mid frequencies) and second for tweeter (high frequencies) by using an Active 2 way crossover that filters the frequency band and send to each of the amplifier section. the cut off frequency can be adjusted by changes few values of resistors and capacitor in the circuit.

In Bi-Amping , the Stereo would mean a total of 4 Amplifiers (2 for left channel and 2 for right channel).

The board we built in this video has single IC (TDA7294) for High frequency section and 2 ICs (TDA7294) in bridged configuration for Low frequency section.

The Board also has inbuilt Rectifier Dual Supply using 4 capacitors (4700/35V each). The Board has inbuilt 2 way Active crossover using Opamps (JRC5532D or NE5532).

The Board Requires 20-0-20 VAC to operate optimally, however 24-0-24 VAC can be used to achieve more power and the Maximum voltage for this board is 27-0-27VAC. Remember, It is recommended to use 8 ohm load for this board to get stable performance.

Link to the Build video is also provided here.

**The IC used in this project is TDA7294 , which is Hi-Fi Class AB Audio Amplifier IC. Refer it's Datasheet for more details :- https://www.st.com/resource/en/datasheet/tda7294.pdf

First we made the design in 3D to visualize the board and then we built the board in Reality.

3D Visualization

Reality

Steps for building the Amplifier Board :-

1) First step is to get the PCB. Here' you can either Make PCB yourself by DIY method (Ironing Method). The PCB design is kept single layer only due to simplicity of making of PCB, OR, you can get the readymade excellent quality PCBs from PCBway.

2) After the PCB, carefully mount all the small components like jumpers, resistors, diodes, Opamps etc. on the PCB and trim their terminals and solder them on the PCB.

3) After mounting small components, mount big components on the PCB like Capacitors, Rectifier, Power filtering capacitors and solder them.

4) After that, now it's time to mount all the 3 IC's on the PCB and solder them. Also mount and solder the Connectors for input and output.

5) Now Mount the heatsink properly on the IC's by using insulating MICA and insulating shoulder washer. remember to use good thermal paste in between heatsink and ICs.

6) After mounting all the IC's on the heatsink. Take a multimeter and check the Continuity between heatsink and IC's back plate. there should not be any continuity between them. All IC's should be insulated from the Heatsink.

The Board assembly is now completed. Clean the Track side of board with IPA (Isopropyl Alcohol) or cleaning flux and then power the board using 20-0-20 VAC transformer or 24-0-24 VAC transformer. 

Remember while turning on the board for the first time, it is highly recommended to use a series bulb circuit to protect the board for any other damage in case if the board has some issues like short circuit, wrong component placement, any Faulty IC etc. 

The series bulb would glow first then it turns off after 2-3 seconds. that indicates the board doesn't has any major issue and most probably running OK.

Now check the input and output voltages of each of the channel. There should be approx. 0 voltage across inputs and outputs of every channel. 

Now Finally, you can connect the speakers to the amplifier board, Give input signal to it and listen to the music and appreciate your hard work and Accomplishment.