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A NOS 192/24 DAC with the PCM1794 (and WaveIO USB input)
A NOS 192/24 DAC with the PCM1794 (and WaveIO USB input)
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Old 6th April 2014, 05:23 PM   #1481
Supersurfer is offline Supersurfer  Netherlands
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Quote:
Originally Posted by juancho View Post
Hi super surfer, what do you mean by 'direct balanced output' exactly? My DDDac distorts if I use it direct balanced output as I presume it doesn't like the two negatives being commoner in my pre
David
That means you directly connect Pos and Neg pins of the dac output to your amp.
But first you need to measure that there is no DC residue on these outputs. Just measure the DC voltage between Pos and Neg, if this is zero or very low, like 0,01V that it would be OK.

You know some capacitors also show some DC leakage on the output (I measured 0,007V dc on a new AN paper in oil cap)

Just make sure your amp and speakers do not get damaged by DC!

Regards,
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Old 6th April 2014, 05:23 PM   #1482
G600 is offline G600  France
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Originally Posted by rhlauranna View Post
here you go:

DDDAC 1794-NOS 24-192

No. 205
Thank you. This is a power plant !
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Old 6th April 2014, 05:28 PM   #1483
rhlauranna is offline rhlauranna  Germany
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Originally Posted by G600 View Post
Thank you. This is a power plant !
you are welcome...

... I am not a technician, but my stomoch "tells" me that we will need something like this not only for the 12 Volt but the supply of the 5 Volt as well...
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Old 6th April 2014, 05:38 PM   #1484
palmito is offline palmito  United States
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A NOS 192/24 DAC with the PCM1794 (and WaveIO USB input)
Quote:
Originally Posted by Supersurfer View Post
I think I will wait for the BBB with the Cape from Russ. I expect he can make it nicer than I can
The isolator recommendation is not to make this better than Russ' solution, it is meant to improve the rpi i2s sound if you are using the rpi. Obviously, an ARM solution that can use a low jitter RCK(s) must be better than the rpi's clock. But if you are using the rpi *right now*, the isolator is a nice and cheap improvement on the sound, since Russ' product is still not available. Besides, I'm sure he will be isolating the bbb form the cape and would not be surprised if he uses the NVE isolator.

Well, for others, besides Supersurfer, that are using the rpi, try the isolator. I think this will be my last rpi/i2s post here since Russ' solution negates all other approaches. Enjoy.

Last edited by palmito; 6th April 2014 at 05:40 PM.
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Old 6th April 2014, 06:33 PM   #1485
mr_whocares is offline mr_whocares  Germany
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Location: germany
Quote:
Originally Posted by Supersurfer View Post
Check this: P5 header

And this: building-open-embedded-audio-applicance

I am a Linux noob so do not ask difficult questions on low level software issues

First I used a distribution with mpd build by a friend of mine, later on RaspiFi and now Volumio.
Volumio is very easy to install and use, and has I2S output on the Pi and within the coming months probably also for beagle bone black!
thanks a lot for the links ...
best regards
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Old 7th April 2014, 01:53 PM   #1486
dwjames is offline dwjames  United Kingdom
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Yes, back in England now after a nice little adventure at the weekend!
Thanks so much to Reinhard and Klaus for the invitation, for taking care of us all with food, drink and wonderful hospitality
So nice to travel so far and meet up with a group of total strangers, but to feel straight away like a bunch of friends all excited together
Klaus's horns and the whole, incredible, purpose-built listening room are truly a thing to behold
And so great to get a good feel for the different variations of Doede's DDDAC design and hear the difference side by side that the modifications and power supplies make to the detail and character of the sound. I'll write a bit more when I have a spare moment, I just wanted to say a quick thanks and how it was great to meet everyone there
cheers,
James
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Old 7th April 2014, 05:15 PM   #1487
Supersurfer is offline Supersurfer  Netherlands
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Quote:
Originally Posted by rhlauranna View Post
you are welcome...

... I am not a technician, but my stomoch "tells" me that we will need something like this not only for the 12 Volt but the supply of the 5 Volt as well...
I think a power supply with low impedance is most beneficial in the analog domain, so for the 8v stages of the dac. The digital domain is less critical in this regard. Digital benefits more by good power supply rejection of noise and isolation of digital noise:so the noise produced in the digital domain cannot enter the analog domain of the dac or amplifiers.

Low impedance supplies can be made by simply overdimensioning; like Bernts supply, of by smart design and use of shunts

The supply of James shows this nicely by bypassing some resistors and the fuse. In this way you will have created a bit more ripple on the dc output but the benefit of lower impedance is much greater than a completely flat dc line. The dc will also be regulated again by the regulators on the board so we can easily get away with this.
Overregulating is not good

I think I will try an unregulated raw power supply on the dac, just to see what it does.
A nice approach will be: big transformer, heavy rectifiers, nice elna silmic caps and chokes ( no resistors in the path); nothing more.

If only I had more time to experiment
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Old 7th April 2014, 06:54 PM   #1488
G600 is offline G600  France
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Quote:
Originally Posted by Supersurfer View Post
I think a power supply with low impedance is most beneficial in the analog domain, so for the 8v stages of the dac. The digital domain is less critical in this regard. Digital benefits more by good power supply rejection of noise and isolation of digital noise:so the noise produced in the digital domain cannot enter the analog domain of the dac or amplifiers.

Low impedance supplies can be made by simply overdimensioning; like Bernts supply, of by smart design and use of shunts
Interesting thoughts.

Quote:
Originally Posted by Supersurfer View Post
The supply of James shows this nicely by bypassing some resistors and the fuse. In this way you will have created a bit more ripple on the dc output but the benefit of lower impedance is much greater than a completely flat dc line. The dc will also be regulated again by the regulators on the board so we can easily get away with this.
Overregulating is not good
Then what do you think of swapping regulators ?
Maybe, like you said, it's better to make the PSU more direct, at a cost of some ripple, and add top notch regulators after ??
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Old 7th April 2014, 07:30 PM   #1489
dwjames is offline dwjames  United Kingdom
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Quote:
Originally Posted by Supersurfer View Post
think I will try an unregulated raw power supply on the dac, just to see what it does.
A nice approach will be: big transformer, heavy rectifiers, nice elna silmic caps and chokes ( no resistors in the path); nothing more.

If only I had more time to experiment
Yes! If we have improved the regulation further downstream with the shunt regs, then a very simple, very low impedance power supply should work very nice

I'd love to try that to compare, but it gives me a few questions:
If there's no voltage drop from a regulator or resistors, then we need a lower voltage Transformer. 9v ac would come out somewhere around 11.5v dc by my calculations. Guido's specs seem to suggest around 3v headroom so that should be OK for the 8v shunts? Or would you go larger?

Any recommendations for suitable chokes?

What size of Silmic caps do you reckon?

Thanks,
James
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Old 7th April 2014, 08:14 PM   #1490
juancho is offline juancho  United Kingdom
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Quote:
Originally Posted by Supersurfer View Post
That means you directly connect Pos and Neg pins of the dac output to your amp.
But first you need to measure that there is no DC residue on these outputs. Just measure the DC voltage between Pos and Neg, if this is zero or very low, like 0,01V that it would be OK.

You know some capacitors also show some DC leakage on the output (I measured 0,007V dc on a new AN paper in oil cap)

Just make sure your amp and speakers do not get damaged by DC!

Regards,
Thanks Supersurfer, it does indeed work very nicely with 4 boards into a 20k load. I previously had two boards and less than 5k load which gave me a bit of distortion.
David
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