The TDA2030AT is an audio power amplifier integrated circuit introduced by National Semiconductor in the early 1990s. It comes in a TO-220 package and requires only a few external components, yet delivers excellent performance, a wide frequency response, and fast response time. Despite being over thirty years old, it's still highly recommended by many audio enthusiasts. One of its most appealing features is that its price has dropped significantly, from around ten yuan to about eighty-nine yuan today. This makes it ideal for hobbyists who want to build high-quality audio systems without spending a lot of money.
What makes this IC stand out is that even at low power output, it can greatly influence the listening experience, especially when paired with a good preamp. Under standard operating voltage, it can deliver an average power of 30W, which is more than sufficient for most home applications. I successfully used the NE5532 preamp circuit with it, and the results were excellent, as confirmed by various electronics magazines. Unfortunately, such high-performance chips are rarely found in commercial power amplifiers or active speakers. While these products may look nice, they often use cheaper circuits like the TDA2030 or unknown alternatives. These are similar in packaging and can be easily swapped, but only genuine parts will provide the desired performance.
Below is the schematic diagram of the circuit, showing only one channel. The other channel follows the same design. There are two schematics provided for reference.
In the past, some electronic articles suggested removing the negative feedback capacitor in power amplifier ICs and adding a DC servo circuit using an op-amp to create a pure DC amplifier. This approach works well with devices like the TDA2030A and LM3886. By eliminating the capacitor, the zero offset was measured to be just a few millivolts, making it very stable. I’ve used this configuration for years without any issues, such as burning out the IC or damaging the speakers. Additionally, the IC includes protection features against overheating and overcurrent. Removing the feedback capacitor expands the frequency response significantly. It’s important to choose the right input capacitors—CBB 1U or brands like WIMA are recommended. Electrolytic capacitors should be avoided, as they can cause instability after amplification. Comparing the sound quality before and after removal shows a noticeable improvement.
Another key feature of this circuit is the current negative feedback design, which is gaining popularity in recent years. Compared to traditional voltage feedback, it enhances low-frequency response and increases gain as the output current rises. However, it's crucial to ensure the power supply has enough headroom. A 150W transformer is recommended; otherwise, distortion might increase. If your power supply isn't strong enough, consider using the conventional voltage feedback method instead.
Here are the PCB layout diagrams for the front and rear power amplifier boards, using two TDA2030ATs and two NE5532s (large S) for the preamp. One op-amp serves as a tone control, while the other acts as a buffer. During PCB design, the front and back stages are grounded separately and connected at a single point to maximize the IC's performance. Once the power rectification and wiring are properly set up, the system can be powered on simply by connecting the transformer’s power cable.
The capacitors used in this project are German-made WIMA capacitors, the NE5532 is authentic SIG production, and the power supply filter capacitors are NICHICOM 25V/4700UF. Their capacity is sufficient for the TDA2030A, and the voltage rating is also adequate since the rectified voltage is around 18V with a dual 12V AC supply. If the transformer voltage exceeds 12V, it's better to use 35V/4700UF capacitors. Metal film resistors are used throughout the circuit.
Capacitors play a critical role in audio circuits, and their impact on sound quality can be significant. High-end options like ELNA capacitors are available for those looking for the best performance. In this design, C2 and C5 are particularly important, with C5 needing to be a WIMA 1µF. The audio channel in this amplifier is almost a pure DC circuit, with only C10 present. Measuring the DC voltage at the output of U2 gives around 0.9V, which is well within the safe range for the NE5532. The sound quality of the TDA2030A and NE5532 has been praised in previous articles and reviews.
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