A NOS 192/24 DAC with the PCM1794 (and WaveIO USB input) - Page 61 - diyAudio
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Old 17th November 2013, 06:51 AM   #601
VuGiaA9 is offline VuGiaA9  Viet Nam
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Join Date: May 2013
If I want to use opt for my 8 deck dac, so what kind of opt like should I use? Please give me some suggestions.
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Old 17th November 2013, 11:51 AM   #602
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Default My DDDAC story

Hi,

I am since around one year in posession of the Doede Dac. I thought it was time to write a review so here it goes:

My setup consists of:
- 4 dac boards
- modified on board shunt regulators (Tent labs), 16 in total
- allen bradley IV resistors, will be changed for Audio Note Tantalum next week
- salas shunt regulators for the dac and wave IO
- balanced connection to input transformer of my tube amps (audio consulting silver volume transformers)
- alix computer board with mpd pup software and linear power supply (tried raspberry pi first but it is not powerfull enough)
- streaming from a NAS
- all controlled with Mpad ipad interface (Super Cool and easy!)

As former designer and current owner the high end CD player of Bow Technologies, (modified with pcm 1794 dac with tubed output), I have been looking for a nice streaming setup without the illusion of bettering my beloved CD player.
Listening to several commercial streaming devices, including very expensive ones, they always sounded less detailed, less organic, less analogue, less real.

However my computer music database was expanding and I opted for the dddac design as a second music source.

After the basic build was ready I was surprised by the sound quality, it came near my CD player and was clearly better than all the commercial stuff I knew.
This was promising.........
Changing the power supplies, building a nice USB cable and connecting balanced to my amps without a capacitor made it clearly better than my CD player and made me very happy!
(This has lead to a lot of work, making bit perfect rips of my complete CD library, but now I can be a couch potato when listening to music with my ipad................)

Now, after almost one year my CD player is covered with dust and ready for retirement.


Some notes on high resolution audio streaming:

High resolution audio failed to give me the satisfaction it should be able to. This has several causes.
1) there are 24/192 issues that are really worse than good a good red book remaster. Some Eagles re-issues are famous for clipping for instance
2) there are also upsampled re-issues, you will understand that upsampling does not really provide higher resolution
3) on the other side: a lot of good 24/192 issues are really bad musical performances I call this elevator music
4) 99% of the best music is not available in high resolution, so we will have to do with red book

I got my hands on some good high resolution issues from Patricia Barber and Miles Davis that are really better sounding than my own MoFi gold disk issues, so it is possible!
So, how do we persuade the music industry to improve the quality?

For the time being, I am very happy playing all my music, being red book or better through my DDDAC.

I want to thank Doede for a very nice design and for his support. Cheers Doede

I have build a second dac for a friend and probably more will follow. I also expect the sound quality will develop even more with Lucian designing a new wave IO and daughter board and mpd pup software being updated for higher performance.

This design shows that open cource and non-commercial design by enthousiasts betters what the industry can do

Regards,

Last edited by Supersurfer; 17th November 2013 at 11:56 AM.
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Old 18th November 2013, 08:21 AM   #603
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Location: a littlee town in western denmark
Hello Supersurfer
Fine Review...i have ordered one..so this is good reading
How much do the shunt powersupply give in sound quality,,,,where on the boards give it most ?--(analog on the pcm1794 ,,or the digital on pcm1794)

can see you change to pcm1794 on the Bow cd,,,,have you change from pcm1702 ??
best Bjarne
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Old 18th November 2013, 08:33 AM   #604
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Hi Bjarne,

I made a mistype, the Bow was mofified with 1704 dac chip and is running non oversampling.
As the 1704 is regarded by most to be one of the best multibit dacs ever made it is quite an archivement that the doede dac sounds better. This however may not directly be caused by the dac because there are more differences like the source being a cd loader instead of a computer.

I did not experiment with trying on digital or analog for the shunts, I have extended experience with other amp and dac designs that a shunt regulator (or no regulator) is always better than a series regulator.

But if you want to try I asume its best doing analog stages first; just my thoughts.

Regards,

Last edited by Supersurfer; 18th November 2013 at 08:36 AM.
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Old 18th November 2013, 08:45 AM   #605
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Location: a littlee town in western denmark
Hello
Yes the pcm1704 sound good ..i have tried it several times..
Now i use a Rakk dac mk3---it also sound good ,,but it is a little sharp in some array--
maybe i will try the shunt on the analog part..i will think it is a bit difficult to do that ,when i have make it all together---so i must do it before
i will use my AMB.org supply for the 12v
Best Bjarne
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Old 18th November 2013, 03:56 PM   #606
clivem is offline clivem  United Kingdom
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Location: London
Quote:
Originally Posted by dddac View Post
No real arrangement as you are the first to ask
I am pretty sure you can do this directly. just send me pm and we will get it arranged...
Doede, thank you for the reply. I'll PM you later this week.

Quote:
Originally Posted by dddac View Post
yes the LED are permanently lit, normally at the standard rate of your operating system when no music is playing.... for example, if you put iTunes in 192 kHz, the 192 led will always be in, till music plays and it will take the actual....

so if this is not the case I suspect your player software
I need to spend a little time more time debugging before pointing fingers. I think the problem is on the hardware side, rather than software. I did play a track at each sample rate and verified via the OS (on Linux: "cat /proc/asound/L20/stream0") that the track was being played back at the sample rate I expected. As I said before, play a 44k1 track and the 44k1 LED flashes at the start of the track and then goes dark after a fraction of a second. Likewise, for each sample rate, the relevant sample rate LED flashes and then switches off. If I suspect anything, it's hardware, relating to the 8mA current source(s) driving the LED's on the WaveIO board side. Nothing to do with player software, I think. Anyway, it's no big deal. (If the board is returned to Lucien for the firmware update maybe he can take a quick look.) If the I2S output stopped working, I'd have an issue. Sample rate display, no issue.
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Old 18th November 2013, 08:19 PM   #607
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Location: GRASSE (France)
Hi friends,

I read on the Luckit.biz page tht the WaveIO supports 32bits 384kHz when the revision ID is >= 0x0331.

But I do not a "revision ID" number anyware on the card. The XMOS chip is marked: "GT1244L1" and "PKH293.09".

I have received the WaveIO card 3 weeks ago (not yet installed), so it should be a recent one, but I would like to know if it is 384kHz capable ?

In addition, is there an indication that it is decoding a 384kHz stream, because the LEDs indicate 44.1 up to 192kHz, but I do not see anything related to 384kHz ...


Thanks

Last edited by Nounours18200; 18th November 2013 at 08:26 PM.
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Old 18th November 2013, 08:54 PM   #608
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I hope Doede will not mind to answer to few questions here!
@clivem please do PMs with Doede and see if the problem is from software or hardware. As for me, I can only guarantee that if the issues is from hardware then I'll solve it as best as I can. Just speak with Doede first since he is the one who will decide what you have to do next regarding your WaveIO.
@Nounours18200: Check my first post here for details on how to find the revisionID of your card!
Cheers,
Lucian
__________________
Contact link for WaveIO USB-to-I2S/SPDIF board.
Daughter card GB list for WaveIO can be found here
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Old 20th November 2013, 12:07 PM   #609
thommy is offline thommy  United Kingdom
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Update on my noise problem:

After installing the 4.7nF caps the quantisation noise has reduced but not gone completely, and there is still a hissing sound coming from the tweeters when no music is playing.

This hissing is a problem on quiet music late at night, and quite painful if the ear lines up directly with the tweeter but during the day with background noise it is not really noticeable. Unfortunately I am currently using the hifi to do some noise reduction work for a client, and part of this involves removing hiss from recordings. More hiss added by the DDDAC is not a good thing here so I am keen to begin to understand the problem better in order to find a solution.

I have yet to reduce the output level of the DAC, i.e. turn down the hiss, because I would like to think it possible to remove the noise at the source.

Also still a little confused about the output stage. Supersurfer above mentions the use of zero output caps because the amps have input transformers. I am currently using 4x basic 2.2 uf mundorfs supplied with the kit. I have not tried to connect the DAC directly to amps without any caps, but the Hypex modules do allow for DC offset adjust. Maybe for me the best way is to adjust the offset and connect the DAC directly. This will of course mean that I cannot use other sources in future without recalibrating the offset. Thoughts?

P.S. This is still the best DAC I have heard.

Last edited by thommy; 20th November 2013 at 12:12 PM.
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Old 20th November 2013, 04:10 PM   #610
jptz is offline jptz  Germany
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Hi Thommy,

think I have the same setup as you have, a 1 board DAC and Hypex NC400 modules.

This is what I did against the hissing problem:

1. I lowered the gain of the NC400 modules by removing the R141 resistor (see: http://www.diyaudio.com/forums/vendors-bazaar/190434-hypex-ncore-104.html#post2837086)

2. Installed the 4.7nF caps on the DAC

3. As IV resistors I used two 68 ohm in series and tapped the signal from the center.

With this modifications I can hear the hissing only with my ear directly at the tweeter.

Because I use a balanced connection and digital volume control no caps or transformers are needed between the DAC and the NC400. Sound is excellent with this direct connection!

Regards,

Jürgen
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