I was fortunate to stumble upon a batch of brand-new power amplifier modules, all of which are classic mass-produced models from different periods, crafted with mature thick-film technology. After professional tuning, their sound quality performance, relying on the rigorous quality control of high-precision semiconductor manufacturing processes, has reached a level that is difficult for amateur DIY to match. I have made a simple comparison between this thick-film module and a classic power amplifier chip of the same power level, even though the latter is a highly respected version among players. This thick-film module still has significant advantages in all aspects - not only does it have a broader soundstage and finer resolution, but its low-frequency power is also significantly different, like the gap between professional players and amateurs.
These thick-film circuits were mostly customized products for professional audio brands back in the day. In the early days, many well-known manufacturers used them to build power amplifiers. Their unique sound quality not only influenced an era but also became a highly recognizable sound imprint in the youthful memories of our generation, leaving a lingering aftertaste every time we listen to them. The original manufacturer producing these modules was later acquired by an international semiconductor giant. The new manufacturer, while continuing the original mature technology, incorporated its own unique design philosophy, resulting in increasingly superior performance of subsequent products. These products are still adopted by many well-known audio companies worldwide, covering various fields such as professional and civilian use.
Following the STK4140, the newly launched STK4137 boasts a more mellow sound, with a stronger bass range and no background noise. It is on par with thousand-yuan devices on the market and is truly a leapfrog product. With a measured output power of 25W at 8 ohms, it exceeds the thrust of a Class D 100W amplifier and is suitable for bookshelf speakers and studio monitors around 3-5 inches in size
Basic performance parameters
Working mode: Class AB
Bluetooth solution: Bluetooth 5.3
Static current: 60mA
Output power: 25W/8Ω, distortion 0.05%. Currently using STK4137. Frequency response: 20Hz to 50KHz
Dynamic range: >100 dB
Overall dimensions: 131*55*250MM (excluding protruding parts)
Overall weight: 2.46KG (including packaging, 3KG)
