I Was Going Too Far with This PCM1704 DAC

I only keep few DAC's for my personal collection. They are all the best DAC I've ever built, but only one DAC that I have spending so much money on it is this PCM1704 DAC using vacuum tubes.

The building process was publish in series post here and the first upgrade was publish in here. The improvement from that upgrade was way better than the first built with many components are replaced with the boutique parts. The cost from this upgrade is expensive.

But how if I going further with changing the remaining standard industrial components with the highest-grade components as well? Will it improve the sound so much?

Let see.

The components are already collected on hands so the process will only replace them one by one.

The list is:

1. The remaining resistor at power supply board are replaced with Takman or Dale Mills.

2. The output resistors are replaced with niobium Audio Note resistor and relocate on the analog board.

3. High voltage capacitors are replaced with Mundorf MLytic HV Power Cap.

4. Low voltage capacitors for vacuum tubes heater and DAC power supply are replaced with Audio Note capacitors.

5. Heater regulated power supply IC are replace from fixed 7806 with LM317 IC regulators.

6. Small capacitors near DAC ICs are replace with Audio Note capacitors.

7. Cables mostly replace with pure silver with Teflon jacket.

8. Generic IEC socket is replaced with Furutech IEC socket.

The picture before this upgrade is actually the same with my last post about this DAC upgrade. The only difference is adding the bypass capacitors output with MIFLEX capacitors.

It gave the sound airier and textures and I will keep it.

So, the first things I do in this new upgrade is start to dissemble all boards, then I start with the simple things, it is the analog stages board.

I replace the heaters capacitors and put the output resistor on the board instead hard wired at the RCA output terminals.

The next step is replacing the high volt capacitors, previously using several Nichicon VZ and this time I only using one high quality capacitor.

The DC filter resistor is also replaced from generic Panasonic resistor to Dale Mills resistor.

The next step is become more complicated because many components that should be replace one by one.

Especially on the voltage regulator board that consist of high voltage DC regulator for vacuum tubes power supply, the heaters regulators, and DAC power supply all in one board.

The vacuum tubes heaters power supply regulators generate heat since it draws constantly more than 300mA each. I relocate the IC regulator attach directly to the chassis. This makes the layout more efficient and tidier.

At these stages, I install the wiring and the IEC power socket using Furutech brand. It is unnecessary components but if you can afford it, then why not.

Finished with all of those works, I can now check the voltage output from the power supply board to dedicated pins and make sure no smoke coming up.

The last section is the DAC board.

Honestly, I am lazy to do this. There so many capacitors that need to be replace.

But I should do it anyway.

It is all done but few things need to be work on is adding extra capacitors on top of each voltage input on the PCM1704 DAC IC and replace the USB cables with pure silver cables.

It is nicely done.

I loved how it looks at the end of this upgrade. This DAC internal components are using high quality with very efficient layout.

I put the tubes on it, then I put the DAC inside my stereo system and start to heat up my system for a while before start listening to the music.

With my favorite music stored on my laptop, then using this DAC, I start to enjoy the music. Not only an album but I listen so many albums and I think I spend great hours listen to the music with this DAC. 

This DAC from previously upgrade was sound great. This new upgrade makes it better but just a bit. With no regret at all, I might go too far with this DAC but I loved it. It paid up my curiosity to having a great DAC with highest quality components inside it.

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