New PCM1794A Kit – Balanced Mode Update – Good to Fantastic Sound!

[skseah]

Hi T C,
Happy New Year...
I am back...after along break...just solved my power amp PSU. Guess the year-end holidays took lots of my time...and also time to wait for my parts.
So the DAC is singing again with my power amps..sounds good..how's your's and Caps rolling getting along?
Have not updated the DAC with the last few suggestions from Spencer.
Best Regards
Victor

[TC Goh]

Hi Victor

Happy New Year too!

I am glad you had a good holiday. We went to Bangkok (yes, again) with the family and had a great time.

After experimenting, I concluded that OCL was the best combination.. ha ha. Could have saved a lot of time and $$$ but I wouldn’t have had so much fun.

I have done Spencer's latest mods but that didn’t change the sound much.

I am now thinking of building a pre amp but this will take lots of skills which I don't have!

How does your system sound after the repairs? How do you like the DAC now?

Best wishes

TC

Originally Posted by skseah

Hi T C,
Happy New Year...
I am back...after along break...just solved my power amp PSU. Guess the year-end holidays took lots of my time...and also time to wait for my parts.
So the DAC is singing again with my power amps..sounds good..how's your's and Caps rolling getting along?
Have not updated the DAC with the last few suggestions from Spencer.
Best Regards
Victor

[skseah]

Hi T C,

Oh, I have not tried any capacitors yet. Guess you can have fun trying the different types of caps. Guess all gives different sound..but which is the best is hard to confirm as our brain cannot remember sound...only if with A/B comparison, then we can tell the difference. I am quite happy with the DAC sound quality now..so not very sure to try OCL...ha! ha!..is there audible difference?

I have not done Spencer's latest mods either..but have bought the Pana caps. Maybe one day I will do it.

Oh, my system sound now is a bit bright. I changed the output tubes, so have to let them burn in for awhile. But with some music, it sounds good..maybe due to the brighter sound.

Side track, are you into photography?

Best Regards
Victor

[TC Goh]

Hi Victor

I guess you will need to give the new tubes sometime to settle in. What power tubes are you using? KT66? What brand? NOS or reissues?

I am a Canon user (have been over 20 years) and photography is my second love. What about you?

Best wishes

TC

Originally Posted by skseah

Hi T C,

Oh, my system sound now is a bit bright. I changed the output tubes, so have to let them burn in for awhile. But with some music, it sounds good..maybe due to the brighter sound.

Side track, are you into photography?

Best Regards
Victor

[skseah]

Hi TC,
I am using the 're-issue' Tungsol 6550. Actually trying them as I could not find the C-wing stock.
Oh..same 2nd love..ha! ha!...but different camp..the Dark side, but not so many years. Started with D200, now with a D700. but I still use a G10. My wife uses it to take photos of me during hoildays, or else I will not be in any photos.
Bye

[Alex_twn]

Hello,

I believe this is my first post on DIY Audio, I am usually more grabbing some information here (shame on me ) rather than giving some on my side, so today let me take the chance to talk about the DAC FDA-1 that I ordered from Fetaudio.com.

I started 2 years ago basically to build my own audio system starting from nothing and I realised the UGS / UP couple from the French forum HCFR.
Very good preamp / amp couple with transparent sound, I was looking then for a nice DAC, if possible full balanced to connect to those already very good preamp / amp.
I tried few kits from eBay but never been really satisfied with the quality in the end.

I ended up one day on Fetaudio and Spencer was releasing his new DAC version based on PCM1794A with a full balanced upgrade, with a specification that was matching my requirements.
After a couple of email exchanges with Spencer (who by the way has always been available anytime and answered fast) and reading several HCFR threads about the quality of DAC D1V33 (the previous version) I decided to give a try.

I ordered straight the full balanced kit that was delivered to my place few days later.
Everything was well packaged, very good component selection, lots of little bags well arranged by parts, at the same quality level as the best group buy I joined in the past for my UGS / UP.

I assembled the DAC in ~ 1 week, a little bit every night, I was really excited to see what will be the result.
All the voltage settings / bias went well and the DAC worked at first power up.

As for the audio quality? Well this is a very good DAC.
Coupled with my UGS / UP, all full balanced, it brings up the listening quality to an even higher level.
Lots of details, very transparent, no coloration, instruments just sound right, huge opened scene (like if I had speakers all around me), great dynamics.

In few words, very exciting, having the feeling again to be excited listening audio records that I knew very well.

Later on I went to all the various improvements suggested by Spencer (I appreciate by the way that he still looks into improvements after releasing the DAC).
So I implemented the new power scheme / grounding, I shorted the output caps and replaced all the 7805 by ST L4941.

The OCL mode (capacitor less) with my system is a great upgrade as since UGS / UP does not have any capacitors on the signal path, the first capacitors seen by the audio signal leaving the PCM1794 are ... in my speakers ...
On all those improvements, the one that really made a significant change is L4941 followed by OCL in my case, I did not really saw the difference with the different power wirings.

My source at the moment is an Apple TV v1 with lossless music deeply modified as well (linear fast power, HDD out, big heatsink / no fan, ..) but I plan to get very soon a nice player that will be also a bluray player with high audio class like OPPO BDP-95 or 93.

Here it is, I am very happy with the product and wanted to give a bit of my comments here.
If you are looking for a DIY DAC, this one is a great one, no doubt, you can go for it.

Last I'd like to thanks Spencer again, first for designing this DAC, and then to answer my multiple - sometimes stupid - questions .

Here are some photos of the finished product with casing for those that would like to see my personal contribution:
DAC FDA-1 (PCM1794A Spencer) - Page 2 - TDG

[TC Goh]

Hi Alex_twn

Spencer designed a great sounding set, didn't he. I had a lot of fun with this build.

I have been away on some personal matter but was very happy to read your post. Like you I have done most of the upgrades except the L4941. It looks like this is a straight swap, is that right?

I will likely attempt this.

Have fun...

TC

[Alex_twn]

Hi TC,

Yes this DAC is really good, I enjoy listen to it everytime I play music

Right L4941 modification is really straight forward, you just have to swap the parts.
I did on my side swapped all the 7805 (4 devices) even if only the ones powering the PCM1794 are needed.
Improvement are there no doubt, the sound quality goes even higher with more opened scene and better dynamics.

I recommend you do the mod, you won't be disappointed

Alex.

[TC Goh]

Alex

Will do. Did some checking on RS and located the ST L4941 part. However, I am away now and will only be able to do this after get home early May. It will be fun though.

To me, the move to OCL gave a very significant boost.

Frankly, I had friends come over to listen to the system and they all leave feeling pleased.

I am using two TXs, each powering one of the boards. I think this may not add much to the sound but it does wonders physiologically ;-) ha ha.

What were you using prior to this DAC? Your source?

Best wishes

TC

[TC Goh]

Originally Posted by skseah

Hi TC,
I am using the 're-issue' Tungsol 6550. Actually trying them as I could not find the C-wing stock.
Oh..same 2nd love..ha! ha!...but different camp..the Dark side, but not so many years. Started with D200, now with a D700. but I still use a G10. My wife uses it to take photos of me during hoildays, or else I will not be in any photos.
Bye

Hi Victor

My apologies for not being active. I had a family health issue I had to take off.

Another builder Alex has upgraded the digital PS regulator 7805 to L4941 with good results. This will be a direct drop in so it will be very easy. This mod was also suggested by Spencer. I will be trying this when I get home beginning next month.

How are your mods going?

I also just bought a HD Video recorder to dabble into the video world. It's is cheapie JVC that is very small and light. Looks like good value.

I have a G9, which I use a lot. It is fairly small and hence portable. My main camera is a 1DM4. This is very capable but is huge. Not very easy to carry around.

As for tubes, I am also starting to use re issues. They are more consistent in quality and supply ..... not to mention they don't cost an arm and a leg and sometimes and eye too!

Best wishes

TC