A NOS 192/24 DAC with the PCM1794 (and WaveIO USB input)

[smooth dancer]

An update from a very satisfied dddac owner. During last year I’ve been using a mix of the new and old dac boards. Why you may wonder ? Well, when the new boards was finished and ready to sing, I wasn’t impressed at all. The sound was to clinical. After a few days I decided to stack four of the old boards on top of the new ones, hoping to get a more forgiving and relaxed sound. And I really did and was happy at that time.

Right after I got nasty tinnitus caused from a long period with nose and ears not in shape. I suspect a type of allergic reaction. This have been going on for two and a half year now, but the tinnitus is almost gone and it’s increadible to enjoy music again.

This again got me thinking on the sound from my dac compared to my friend’s dac who have for new boards and sounds just great. Therefore i removed the old boards and sat back with the four new one. Guess what, the new boards are much better in all hifi terms.

It seems that I was not patient enough when the boards where new and they needed longer time to show how good they really are.

I also got a tip to you guys who use Lundahl 1694 filament chokes in psu. When my ears got better I could hear a lot of white noise from the speakers when not playing music and the volume turned up to max. After som thinking I decided to wire the chokes in serial commond mode. Voila....no noise. Take a close listen and try if you have noise at any level.
The voltage out from choke is very close when wired in series or series commond mode.

Best
The dancer

 

[dddac]

An update from a very satisfied dddac owner. During last year I’ve been using a mix of the new and old dac boards. Why you may wonder ? Well, when the new boards was finished and ready to sing, I wasn’t impressed at all. The sound was to clinical. After a few days I decided to stack four of the old boards on top of the new ones, hoping to get a more forgiving and relaxed sound. And I really did and was happy at that time.

Right after I got nasty tinnitus caused from a long period with nose and ears not in shape. I suspect a type of allergic reaction. This have been going on for two and a half year now, but the tinnitus is almost gone and it’s increadible to enjoy music again.

This again got me thinking on the sound from my dac compared to my friend’s dac who have for new boards and sounds just great. Therefore i removed the old boards and sat back with the four new one. Guess what, the new boards are much better in all hifi terms.

It seems that I was not patient enough when the boards where new and they needed longer time to show how good they really are.

I also got a tip to you guys who use Lundahl 1694 filament chokes in psu. When my ears got better I could hear a lot of white noise from the speakers when not playing music and the volume turned up to max. After som thinking I decided to wire the chokes in serial commond mode. Voila....no noise. Take a close listen and try if you have noise at any level.
The voltage out from choke is very close when wired in series or series commond mode.

Best
The dancer

Thanks for sharing this long term results at the forum! Indeed Paulus recently mentioned also that burn-in takes a longer time as usual or expected, but it is worth to keep the dac switched on, 24/7 in the beginning, for at least a few weeks. If you only listen 1 hour a day, it will take you months ;-)

 

[boldname]

<<Right after I got nasty tinnitus caused from a long period with nose and ears not in shape. I suspect a type of allergic reaction. This have been going on for two and a half year now, but the tinnitus is almost gone and it’s incredible to enjoy music again.>>


This is a probably an underestimated issue for many of us, What is more, the tranche of mild winter colds and viruses can also impact our subjective appreciation of the sound.

 

[stefan646]

Some quick questions:
In the DDDAC manual it says "Hold the minus (black) of the multi meter (DMM) to the analog output pin ’com’ from the main board. " , and on the schematic PDF is written "NOT common at main board" . In the manual should be written "from the board" instead of "from the main board" ?

The wattage load for a 4+ board DAC is too much for SMD resistors.

I don't understand this statement.
I have 4 boards and intend to use 6 200 ohm Susumu 1206 RG. If 3 270 ohm resistors in parallel could drive 2 boards, why would't 6 parallel resistors be enough for 4 boards? What I am missing?
Thank you !

 

[Bfpca]

<<Right after I got nasty tinnitus caused from a long period with nose and ears not in shape. I suspect a type of allergic reaction. This have been going on for two and a half year now, but the tinnitus is almost gone and it’s incredible to enjoy music again.>>


This is a probably an underestimated issue for many of us, What is more, the tranche of mild winter colds and viruses can also impact our subjective appreciation of the sound.

I agree. If you are feeling unwell, particularly if it is a head cold, allergy or sinus issue it can really effect how you perceive sound. I deal with ongoing sinus issues and have learned to not make any quick decisions about sound quality.
I have had a single board DDDac for about 6 months now. I was having some issues with inconsistent sound quality in the higher frequencies when up sampling to 176 or 352. I was using Pure Music 3 and had the up sampler set to maximum fidelity by default.
Eventually I tried changing the up sampler to classic NOS mode, whatever that means, at 352khz. This got rid of the HF issues and now the dac sounds fantastic. I'm not exactly sure what NOS mode up sampling is but I think it might be that it just inserts equal samples and does not interpolate. I am running an older mac mini and that may also have been running out of cpu when coping with the more computationally intensive maximum fidelity mode.
I have also built a separate power supply that uses 2 transformers with a large toroid and a CLC filter feeding +15volts to a DEXA 12Vuwb regulator mounted right at the 12v input terminals on the DDDac board. I have very low noise levels even when using 95db sensitive speakers. The rest of my system is an Aikido tube preamp and a pair of First Watt F5V3 monoblock amps. I want to build a balanced preamp to try running the DDDac balanced. I may also try transformer based BAL/SE conversion. Right now I am renovating my house so my time for audio projects is limited for the next couple of months. It's good to hear from other users and hear what they are experiencing with this fine DAC.
Once again, I would like to thank Doede who's excellent design skills and listening abilities have brought us this very musical DAC.

 

[Weymario]

Swap out the cables at the analog out on the DDDAC board to verify the issue is on the DDDAC board(s) and not somewhere "downstream" (wiring, transformers, etc.). If the issue really is on the DDDAC, check the I/V resistors. Are they (still) all the same value? Solder connections ok? My next steps would be (1) to check if the input data is not somehow "unbalanced" (*) and (2) take off one DAC deck after the other and see if the problem can be isolated to one of the decks.

[*: I once thought I have a broken DAC (not DDDAC) and sent it in for repair, but it was perfectly ok. It turned out I somehow managed to modify the digital data so become out of balance...]

i checked the voltage between pos/neg after the I/V resistors (the resistors have the correct values) with a 50Hz sinus: left channel is 1,195V, right channel is 1,206V (after the volumecontrol- a TVC- at maximum level there is the same voltage; though the volumecontrol works correctly) -> can you hear this different voltage (i have loudspeakers with 100dB sensitivity)?

thanks, mario

 

[dddac]

i checked the voltage between pos/neg after the I/V resistors (the resistors have the correct values) with a 50Hz sinus: left channel is 1,195V, right channel is 1,206V (after the volumecontrol- a TVC- at maximum level there is the same voltage; though the volumecontrol works correctly) -> can you hear this different voltage (i have loudspeakers with 100dB sensitivity)?

thanks, mario

If you have 1,195 and 1,206 Volt RMS output the difference is 0,08dB ..
That is considered a perfect channel match. no way you can hear that. regardless of the sensitivity of your speakers.

have you checked the voltage across the speaker terminals?

 

[Weymario]

If you have 1,195 and 1,206 Volt RMS output the difference is 0,08dB ..
That is considered a perfect channel match. no way you can hear that. regardless of the sensitivity of your speakers.

have you checked the voltage across the speaker terminals?

thanks doede! very good news
i checked the voltage across the speakerterminals and get for example:
left: 6,522 right: 6,514 (full volume)
le: 1,8010 ri: 1,7468 (middle volume)
le: 0,0591 ri: 0,0587 (very low volume)
seems to be correct? maybe my ears have a problem or i had a bad connection because after moving the parts it seems to be correct ( there was no time to listen again).
thanks, mario

 

[mbrennwa]

i checked the voltage across the speakerterminals and get for example:
left: 6,522 right: 6,514 (full volume)

That's a 0.01 dB difference.

le: 1,8010 ri: 1,7468 (middle volume)

That's a 0.26 dB difference.

le: 0,0591 ri: 0,0587 (very low volume)

That's a 0.06 dB difference.

Very good matching of the two channels indeed! Your volume pot may be a wee bit louder on the left channel in the "middle" setting, but still pretty good.

 

[Weymario]

thanks mbrennwa!
which formula do you use to get the dB from the voltage?

doede,
dick from audio-creative wrote, that you now use their magic power suplly. would you recomend this?
best mario

 

[audionut]

In my DDDAC/Tent four board system

I am using some very large transformers for the supplies...because they were on hand.

After rectification, the power goes through super regulators...then to the DDDAC...

I think to beneficial effect.

 

[mbrennwa]

thanks mbrennwa!
which formula do you use to get the dB from the voltage?

difference in dB = 20 x log10(V1/V2), where V1 and V2 are the two voltages.

doede,
dick from audio-creative wrote, that you now use their magic power suplly. would you recomend this?
best mario

I'd like to get one just to open the oh-so-magic box and see what's in it. I am sure it's not magic at all.

 

[smooth dancer]

New parts ready to be installed.
Rectifier bridge from Sjøstrøm Audio and modified psu’s .

 

[Despearce]

I have a problem with a dddac I built over a year ago. I took it out of my system yesterday to take to a friends, when I got there it had stopped working. I tracked it down to the rca terminal and switched it off and brought it back home. This morning I resoldered the connections and still get no sound.

I have 40mV at the correct points, when I measure the output at pos and neg on the mainboard I see 6mV on the right channel and 2mVon the left, would this be the cause and how do I fix it?

 

[smooth dancer]

Separate psu.
Two big R-core transformers, 23v-300va for 12v dac boards (4), and 15v-300va 5v (waveIo).
Rectifier bridge from Sjøstrøm audio.
Lundahl 1694 filament chokes, 1.5A.
Mundorf mlytic 10 000 uf caps.
Stock psu with bypassed fuse.

Next coming up is to mount dac boards, waveIo and Cinemags transformers.

 

[67339]

Hello,
A bit similar to my power supply. Right now i am using a kind of standard schottky diodes but they will be changed into the ones that won the contest in linear audio magazine.
My diodes are mounted directed onto the lundahl "" connection board"" and if i am right the first mundorf cap is there too. After that there is the second choke and the last cap.
I am using the ll2733 because i wanted higher mH. You are using in them in what lundahl calls common mode connection. For me that one sounds best.
I think you already know that there will be a big voltage drop with the lundahl ( mines even have higher dcr) . BUT many people think it will make the power supply slow but i think the bigger the choke the more powerfull the sound will be.
If i remember well you are using high efficiency drivers just like me. You will be surprised of the impact of a good choke input power supply.
I have been trying to persuade people using choke input for class A solid state power supplies but they wont listen.
My friend is using ll2733 in a small power Nelson Pass design. Works very well. Because it is a single rail power supply he can use ll2733 in common mode connection. So there will be 2x1,7 ohm dcr right after the rectifier but the amp still sounds very much in control.
Dave Slagle also developed a dual coil choke for the Coleman heater supply. There is one for 2 and one for 3,5 A could be used for dddac too. I think lower dcr but also lower mH. You should ask him.
Greetings, Eduard

 

[smooth dancer]

Hi eduard. Long time.

Finished at last. Been working all weekend soldering and moving old and new parts over from one case and put separate psu and digital separated in two cases.

Here is a lonely four board dddac with Cinemags and WaveIo.

 

[mbrennwa]

There is still a lot of space for stuff in this case

 

[smooth dancer]

At the bottom of the rack.

 

[smooth dancer]

There is still a lot of space for stuff in this case

Jepp, I wanted to have the same size on the cases from modushop. Think it’s lookin better this way.