Last week, we held a simple DIY Blind Test session. The contenders were all Class A amplifier (we can see F5, J2, Aleph, TUMOS, and some others…)

This was a hot session. Not just because the contenders were very good and serious, but the Class A itself means high current (=hot) and big heatsink (=heavy). So? You can imagine the rest 😉

Below is the preparation of the session. The speaker was DIY 3-way with Vifa driver (XT25, P17, and PL26). The CD Player was CEC, while the Preamp was Aikido. Enjoy some photos below!

This was a branded amplifier from China, named Yaqin. It’s considered as hybrid, as you could see the tube with solid state output. Quite affordable and sounded quite OK. Price performance wise, you couldn’t get more!

Ready to travel? Anybody?

A prototype of a balanced/unbalanced preamp. Could you guess what was that?

Small but hot. A fully tweaked Class A Amplifier. Done by point-to-point wiring.

Another serious Class A Amplifier. I believed it was based on Pass J2 design. Powered with Talema transformer and Kendeil capacitor.

An F4 Hybrid Amplifier. Based on my observation, it still needed some improvement on some aspect.

Pass F5 with some NOS transformer and capacitor.

Another hybrid amplifier with #27 tube. It was based on TUMOS. A small but hot amplifier, but the owner itself doubt could run it for long time without additional heatsink 🙂

Another serious design for Class A Amplifier. Most of the budget shall be allocated to set a good heatsink/chassis. Another cheaper solution was to use active cooling with small fan, but you shall trade off with smaller chassis with extra noise from the fan itself.

Another unique design with upside down amplifier. Power supply on the bottom, the amplifier on the top – upside down position.

Pizza delivery? 🙂

The first winner, based on Pass J2 and giant Sprague Sangamo capacitor (nearly 0.5 F there!). Also you could see dual Talema potted transformer there.

Hybrid TUMOS and #27 surprisingly could take the 2nd position, even without too many boutique parts. Good job!

The third winner was the Mini Aleph, based on kit PCB. Surprisingly, this kit also sounded very good, probably also supported with some vintage but good parts.