This Week I Learned - 2017 Week 38

The usual stuff or last week post.

Long weekend holidays. More rest and clean up.

Fluff in Scientific Writing by Celia M. Elliott (PDF). Right, I definitely write in a fluff way. Awareness is the first step to improve your own writing.

So you have a pair of passive speaker. What now? The next step is to get a DAC and an amplifier. Or you can get a Class-T amplifier with build-in USB DAC and headphone amplifier combo like Topping TP30-MARK2. The USB DAC let the amplifier serves as an external sound card so you can channel out the sound from your PC through the USB.

As I learned in the last week post, the quality of any amplifier is the whole sum of its electronic components, especially the amplifier chip and capacitors. Screenshot below illustrates the PCB board and its components. Unfortunately, the amplifier chip is Tripath TA2024, which push about 15 watts per channel, a bit lacking for bookshelf speakers.

SMSL SA-36A PRO, while it's a affordable and quality amplifier, has two different versions. To save cost, the manufacturer have switch the amplifier chip from Texas Instrument TPA3118D2DAP to STMicroelectronics TDA7492PE. The general consensus from the reviews and forum discussions recommended to get the TPA3118 version. Maybe the SMSL get a better pricing from STMicroelectornics or Texas Instrument cannot keep up with the demands. This also reminded me of certain manufacturer which produced quality and affordable first generation of said product to get good rave reviews and slowly replace with cheaper components for next generation.

Unfortunately, SMSL SA-50 is currently out of stock and I can't find it in the SMSL website. Maybe SMSL decided to phase it out from the market? What about SMSL SA-60? It's not shown in the official website as well.

Neurochome's LM3886 done right? The correct amplifier design compare to others like Circuit Basics or Electronics Lab. I believed Tom Christiansen's experiences at Texas Instrument allows him to design the most optimized audio amplifier using TI LM3886 amplifier chip.

YouTuber FFcossag channel is what I consider good review, teardown, and educational on a particular amplifier. Good example was how he evaluated through the specification of Breeze Audio TPA3116 as shown below. Even better, his videos are in public domain! While we need to absorb and digest large unknown information, his does provides a quantitative (objective) rather than qualitative (subjective) analysis of an amplifier. Sometimes, it sounds nice to the reviewer is a personal taste.

While we're on Breeze Audio. Be extra careful when you plug in the power supply. One reviewer, NFM popped and burned one of the capacitor while testing it. Luckily he was protected by the aluminum case. Be extra careful with all these low end amplifier, supply lower power to the amplifier or you switch the capacitors to a higher voltages type. It does raises quite a lot of safely concerns with all these low cost amplifiers (no quality control, cheap or cloned electronic components) from China.

FFcossag also provides another excellent objective review on popular Lepai LP-2020A+. See video below. While the amplifier is way under-power compare to what the manufacturer claimed in the spec sheet, it's still value for performance worthy amplifier. However, the same problem exists. You can't bloody get this amplifier in MY and have to try your luck sourcing it from China.

Similarly, he also trashed the Lvpin LP-838 and make the consumer aware of what are they getting of buying a cheap amplifier. To save cost, certain manufacturer will reuse or recycle certain components. Is it safe? Hard to tell but it certainly does not increases any confident (more on this later) in using the product. Be an informed buyer, buy from reputable dealer and brands.

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