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.

300B Tube Amplifier Build

The 300B tube can be the holy grail of every tube amplifier. Everyone praises for its sweet sound. Personally, I never compare directly between one amplifier to another amplifier using 300B tube, but I still believe the reputation of this 300B is not a false statement.

More specific, the single ended 300B design are well known for the best sounding amplifier compare with the push-pull. Single ended is also more economical approach since we only need a pair of 300B tubes. But it has the drawback, it is the low power output. It is about 6 watt per channel.

That is why in this 300B tube amplifier build, I will make this amplifier in single ended design with 6SN7 driver and 5AR4 rectifier to drive a headphone.

For headphone? Pretty disappointed?

I guess not. I hope the sweet sound of 300B can be heard more closely to my ears.

Fresh Catch, The Parasound DAC 1000

Sometimes we bought the vintage audio equipment's not because only for the built quality, or the sound signature, or the price. I bought this Parasound DAC 1000 because it looks just like new.

Parasound is the big name in 90's which at that time, I am just can saw it on the borrowed Stereophile magazine. So, when I saw this DAC today and sold to me for under $300, who can resist?!

IBASSO DX-90 Disassembly & The Capacitor Replacement

It has been a while I am not posting anything in this blog. This is because of my main job schedule is very tight, so I cannot even manage this blog at all. But thankfully I am still having my routine music listening session, probably a few hours a week, with the current audio setup is using the low cost AD1865NK DAC, the LM3875 Gainclone amplifier and SB-acoustic 2-way speaker system. For the digital player is iBasso DX-90 which I have used for very long time.

I am curious what is inside this tiny media player and I have an opportunity to open it up now.

Low Cost, Great Sound AD1865NK DAC Build

It started when I tidied up my storage bin on last weekends, I remember that I had an unused AD1865 DAC complete board from my previous DAC project. This board is okay, I think it performed quite well at that time, but I immediately replaced it with another DAC project because my curiosity is much faster than waiting 100 hours of capacitors break-in.

So here it is, an old AD1865 DAC board with new refinement and better calculation, using all parts I have in my bin. The building cost is nothing because all the new parts are already in my hands.

Miflex MKP-14 Capacitor for Speaker Cross-over Upgrade

Continue from my previous speaker cross-over modification from -12dB to -6dB slope, I satisfy with the result and I would replace the capacitor to the better one.

I had used many high-quality capacitor on my previous project and for this cross-over capacitor component, I will prefer to use Miflex MKP-14, which not only for it's affordable price, but in my opinion, the quality is better than Jantzen Cross-cap or Mundorf MKP.

Speaker Crossover Comparison -12dB Vs. -6dB Slope

We are fully aware that the speaker is the end of every audio chains. In my experience, once I get satisfy with a pair of speaker, then it will sit there for very long time. The reason is because every speaker has their own characteristic to match with the room acoustic and personal taste. This is not easy to having the right one, and of course with affordable price.

My speakers is the 2-way system, they are consisting of 2 drivers from my local brand, SB Acoustic SB16PFC25-8 for mid-bass and SB19ST-C0004 for tweeter. I've listening to this speaker for quite long time with the -12dB crossover point, or commonly known as 2nd order slope.

They are all good, but today I want to try the -6dB crossover point.