Dual Op-amp Upgrade In The Hybrid Vacuum Tube Headphones Amplifier

Last year, I made this hybrid vacuum tube headphones amplifier project. The basic idea is based on the pictures on the internet that a headphone amplifier is using a vacuum tube with only 2 pieces of AA batteries. It is visually (from the internet photos) can drive the full size tube on it. I curious because there is no proven or any review about this vacuum tube amplifier in a working condition yet.

Then comes to the conclusion when I built one here, it simply doesn't works at all. The power from 2 AA batteries cannot heat the tube heater, thus increasing the voltage doesn't help it at all. Because it facing with power supply current issue, not the voltage issue.

I changed the layout by simply using 12 volt 2 ampere external switch mode power supply. Then the final layout is using Nichicon UKA as upgraded capacitors here and I also using the 3 batteries 18650 in series with total 12,6 volt 2.200 mAh here. It is now a working hybrid vacuum tube headphone amplifier.

For high efficient earphones, this amplifier can drive properly. My Sony MH-1C sometimes can sound wonderful with this amplifier but for more complex music that require more power to attack, this amplifier still feels lack of power to drive this earphone. The sound in a simple music when it drive the high sensitivity earphone, can sounds detail and wonderful.

So I guess I need to rework this vacuum tube amplifier again. The candy tin as the amplifier case previously is too small and cannot fit so much components in it. Especially for the buffer stage that using an op-amp for both channel also not deliver so much power to drive an earphones.

Obsolete DIY Audio (Part 2) First Watt B1 Buffer Preamplifier

I continue this topic about what certain do it yourself (DIY) audio that obsolete, means it used to be good but not for today standard.

The First Watt B1 Buffer preamplifier are published around 2008. It is very popular buffer preamplifier among DIY audio at that time and I am the one who also praised it very much. You might probably know the buffer function in audio system, in the First Watt article about this B1, it is explain the function completely by the audio guru, Mr. Nelson Pass. In short, this buffer function is for impedance matching between input and output, from the source to the amplifier.

I always said this is just like a preamplifier but without additional gain. I have made this B1 buffer 3 times in the past and they makes me smile. Mostly I combined this B1 buffer with the Gainclone amplifier. This makes the music more deeper in sound-stage and reveal the details.

For that reason, I will make it again right now.

Obsolete DIY Audio (Part 1) Tripath TA2024 Amplifier

Do it yourself or DIY for the audio equipment is a journey.

You get better experience over one project to another, either it is a good project or the fail one. This DIY audio is not cheap. I always say it to the new comers. I started this hobby when I am teenager, then it keep continues until now. This hobby right now is far easier than my past. Especially with so much information over the internet right now, all problems seems not a problem at all. If I summ all my tools and spare parts cost, they will be worth for moderate audio system.

So what related this intro to this post anyway? Well, in the past, I experience many audio project that give better result. Sometimes, I was wondering how they perform right now? So I will build it again to test in my current audio system.

Right now, I still wondering how good is the small class D amplifier. The famous one is Tripath  TA2024 amplifier that I have praised it very much in the past. This is a very efficient amplifier, running single supply, means can using battery which is really capable and reliable. The power output only about 6 watt per channel, but if pair with the moderate efficient speakers, it can sing very well.

That is my experience in the past and how is will perform right now? So I will make this Tripath TA2024 amplifier again, only to pay my curiosity.

Nakamichi DAC-101 (Part 6) Decoupling Capacitor Upgrade

I think this is the last post for Nakamichi DAC-101 components upgrade.

At this moment, this is the best sounding DAC for me, especially since my previous components upgrade. Those steps makes this DAC sound quality significantly better and it also improve the reliability of the unit.

But something across my mind about the decoupling capacitor on the TDA1541. This capacitors function are for the active divider inside the IC. Based on the datasheet recommendation, the capacitor value are 100nF each. There are 14 pieces for each TDA1541. Interestingly for most vintage hi-end CD player which using the same TDA1541 as the DAC, the capacitors value are more than 100nF up to 470nF.

So by looking inside this Nakamichi DAC-101, I will share the upgrading process of those decoupling capacitor using 470nF Wima MKS. Then I will find out how this upgrade improve the sound quality.

Nakamichi DAC-101 (Part 5) Op-amps & Capacitors Upgrade

The upgrade of this Nakamichi DAC-101 is continue. Previously, by using the external linear power supply to this DAC unit gives significant audio improvement.

The DAC IC alone is not the only factor that determined how good the DAC could perform, but what comes around to support the DAC really matters to reveal the true potential of the DAC itself.

I think the analog stages after the DAC contributing a lot for the better sound. This Nakamichi DAC-101 analog stages is divided by many section, but I will explain based on the schematic and where should I start to upgrade it.

Please continue reading.