300B Amplifier Hum Problem Solved

My previous post about the 300B tube amplifier build was a breakthrough for myself. That was my first 300B amplifier build that by its nature is direct-heated triode. I read everywhere saying that 300B amplifier will always have small hum present at the output. Mostly when pairing with the speaker sensitivity above 88 db. My 300B amplifier was built intended to drive a headphone. It is also can act as pre-amplifier. I only can imagine the result will be small hum present and I should accept it.

But the result is worse than my expectation. The hum is not at the acceptable level, even with the volume control fully closed.

I think more than a month I tried to figure it out, and with the help of one of my friends, now this 300B amplifier is completely free of hum.

Yes, you are read it correctly. No hum at all, it is dead silent. Only great music.

Portable TDA1543 DAC Preamp & Headphone Amplifier

I've built DAC with pre-amp and headphone amplifier combo several times which surprisingly sound good. Moreover, this might become more practical unit that act as headphone amplifier and can be also connect to home audio system with the same output from the unit itself.

I made PCM63 DAC with this combo here, long before that, I also made portable TDA1543 DAC combo here. The secret of those combo lies on the current output booster that act as buffer, lowering the output impedance which easily drive any headphone or as a signal output to feed the home audio system.

Especially in this post, I will share my latest upgrade for my previous TDA1543 portable DAC combo that I've built last time. This upgrade resulting to better sound quality.