The Ultimate R2R USB DAC PCM1704 With Vacuum Tubes Output (Part 4) Review

For me, this ultimate R2R USB DAC using PCM1704 and vacuum tube as the analog output is the most ambitious project that I wish to have, and I am glad that I had it right now.

Think about my previous DAC built are all using op-amps IC for the analog section. They are many variation of them and I just wondering how would the vacuum tubes sounds like when using in the analog stages of a DAC. What the difference between using all op-amps and passive IV with vacuum tubes at the analog part of a DAC?

This DAC built is the answer for all my curiosity.

But before going to the conclusion, let me updates about the progress of this DAC I've made so far since the last built in the part 3.

For the sound performance and the DAC circuit itself, it has no issue at all. It run perfectly well.

My only concern is at the regulators power supply for tubes heater. Each tube using one 7806 positive regulator and they run very hot.

I put the small heatsink that I think would be enough for the regulators, but for long period of time, I don't think this will be reliable. I couldn't touch the heatsink more than 5 second when this unit operate for a half hour.

The solution for this is I relocate the regulators heatsink directly attach to the chassis.

This helps the regulators in transferring the heat to the chassis. This solution is simple and I think this DAC can be operate all day long.

The others updates are only cosmetically improvement.

I think the top aluminum panel need to be repaint. Since the last time I did the painting are quite a mess. This is what it looks like before the repaint.

The black color is uneven.

And since I am using USB C as the digital input, I need a bigger hole at the back panel to accommodate the USB C cable socket connect to it.

The repaint result is so much better.

I can continue to assembly the parts together.

I listening to this DAC for quite long time and I can conclude that this PCM1704 DAC using vacuum tubes output is the  most musical DAC I've ever heard.

The vocal sound really have a body. It is the most engaging experience for this kind for presentation.

The treble sound is smooth but effortless. Not Edgy and at the same time not dull at all.

The details are not extraordinary, but I can hear all the detail instead.

The bass are solid punch without any interfere to others mid-bass or vocals sound.

This is quite strange feeling listening to this DAC, but I really enjoy it. It is very musical which the more I listen, the more I immerse to the music itself.

So, is this DAC using vacuum tubes output is better than previous built DAC using op-amps?

Not really.

It return back to the listener preference again.

I still can enjoy the more precise, detail pin point and at the same time smooth sounding DAC when using the op-amps, but at the same time, there is a magic when the vacuum tubes DAC produce the sound quality. It makes you enjoy it and want to listen back again to it.

The PCM1704 DAC behave so much differently when I listen from where it's belong previously, inside the Clarion HX-D1.

You probably heard many times I review the HX-D1 sound is so much details and precise. The frequency response is soo wide. While HX-D1 capable to read HDCD format, but it get worse to the sound quality that's makes me dizzy of that high-resolution sound.

But when the same DAC IC install in this vacuum tube DAC, the sound are not the same at all.

It is very musical.

Disclaimer: Any statement and photos in this article are not allowed to copy or publish without written permission from the writer. Any injury or loss from following tips in this article is not under writer responsibility.