Thomas Bethe built an audio hi-fi amplifier using two TDA2050 integrated chips. I haven’t seen these chips used in projects in a while, because it’s pretty known that TDA2030, TDA2040, TDA2050 chip family is not the best so to say. I remember some years ago, a local factory was building hi-fi amps using these chips and how often i needed to replace the destroyed TDA’s. Their Pentawatt package is not very good. These ICs are more suitable for TV sound amplification, radios, applications in which they drive some small full range speaker.
The speakers Thomas wants to use with his amplifier are a pair of Klipsch RB-51, which are pretty small and well behaved. In the TDA2050 datasheet it is proudly stated that the small chip can deliver 32 Watts RMS into 8 ohms with 10% THD. At this level of distortion those Watts are actually WHATS?! From graphs we can see it can actually deliver about 18W into 8 ohms and stay in the hi-fi area of 0.1% THD.
The schematic used is the split power supply version from the datasheet with an additional feature, headphone output. Thomas used a MKP capacitor at the input of the amplifier circuit. Although it’s always best to use high quality components, i wonder if any differences can be noticed with the TDA. The construction is pretty simple, just a few external components are needed but as the author says the layout is very important in reducing noise. So follow the advices he points in his article.
The amplifier is connected to +/- 25V supply rails, therefore it is not recommended for this amp to be used with 4 ohms loads. If you have low impedance speakers use +/-18V supply. Thomas’ power supply seems to me an overkill but i guess it does the job. If you plan on building this amp yourself screen the power supply and avoid crossing the wires carrying audio signal above power supply.
As far as how it sounds Thomas seems to be happy, even calls it a “mini gainclone”. To me the TDA’s don’t stand at the same level with National Semiconductor LM chips but it’s purely subjective opinion. Anyways anything you build by yourself is ten times better than what you find in the market for the same price as your investment so happy soldering.