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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 17th April 2019, 09:11 AM   #6861
mbrennwa is online now mbrennwa  Switzerland
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Quote:
Originally Posted by kartick View Post
- use only any one ground connection and not three or four against each Data, BCLK, etc.
Yes! And also remember might be yet another GND connection via the power supplies of the DDDAC and the RPI+HifiBerry (if both power supplies are connected to the same GND). Adding a dedicated GND wire at the I2S pins will therefore create a ground loop. I have to say that this ground loop is not an issue in my case, and I do have a dedicated GND wire between the HifiBerry and the DDDAC.

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Originally Posted by kartick View Post
- Don't solder these wires
That's interesting one! I don't doubt your observation, but it would be interesting to understand what's going on.

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- In case you are not using Moode, try using that.
Nothing wrong with MOODE, but Volumio will be totally fine to get a clean I2S signal.
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Old 17th April 2019, 09:32 AM   #6862
kartick is offline kartick
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Since i2s is a sensitive connection, maybe soldering exposes some type of connection and hence grounding is a problem or maybe... I am not an electronics person so ignore if this does not makes sense. But it is my practical observation and i tried doing this multiple times and got crackling noise every single time.
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Old 17th April 2019, 12:43 PM   #6863
dddac is offline dddac  Germany
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Originally Posted by mbrennwa View Post
Why not run everything else through the transformer volume control, too? Ok, it would be a bit of work to build a chassis with a selector switch and stuff, but a transformer volume control really is a good thing. I stopped using conventional resistive attenuators, because they basically "burn" must of the music signal to reduce the amplitude
Indeed optimum solution - I have the "special dddac" Sowter with 18 taps at the secondary. I use my own built remote control (arduino) and 18 relais to select the taps. Indeed somewhat more work, but an excellent solution.

Frequency response straight line 20Hz to over 200k (my AP stops at 200kHz ) and only 10 degrees phase shift at 200kHz and 20Hz
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Old 18th April 2019, 12:21 AM   #6864
deafbykhorns is offline deafbykhorns  United States
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Quote:
Originally Posted by mbrennwa View Post
Why not run everything else through the transformer volume control, too? Ok, it would be a bit of work to build a chassis with a selector switch and stuff, but a transformer volume control really is a good thing. I stopped using conventional resistive attenuators, because they basically "burn" must of the music signal to reduce the amplitude
My preamp has a TVC already at the output of a 301a tube and it works very well!
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Old 19th April 2019, 09:20 AM   #6865
schiirrn is offline schiirrn  Germany
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The noise problem is solved. Unfortunately I only figured out the requirements and limitations of the DDDAC Pi combination once I had it on my bench and in my specific case that appliance is completely useless. I got a € 25 AptX Bluetooth thingy that does everything I was looking for without any hassle and without any noise issues.
The DDDAC is sold, it was a waste of time and money.
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Old 19th April 2019, 12:37 PM   #6866
juancho is offline juancho  United Kingdom
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Quote:
Originally Posted by schiirrn View Post
The noise problem is solved. Unfortunately I only figured out the requirements and limitations of the DDDAC Pi combination once I had it on my bench and in my specific case that appliance is completely useless. I got a 25 AptX Bluetooth thingy that does everything I was looking for without any hassle and without any noise issues.
The DDDAC is sold, it was a waste of time and money.
If you can't tell the difference between a Euro 25 Thingy and a properly set up DDDac then you are right: it's a waste of time and money for you and the money's better invested in hearing aids
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Old 19th April 2019, 08:23 PM   #6867
schiirrn is offline schiirrn  Germany
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What hearing aids do you suggest? Noise canceling headphones?
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Old 19th April 2019, 08:30 PM   #6868
juancho is offline juancho  United Kingdom
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Originally Posted by schiirrn View Post
What hearing aids do you suggest? Noise canceling headphones?
They'd do very nicely!
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Old 20th April 2019, 09:46 AM   #6869
eduard is offline eduard  Netherlands
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Default update on my DDDAC

Hello,
My DDDAC is back in the audio rack at the level of my head. I thought it would be lighter after removing the big transformer and the little choke and replacing them by a small transformer and a BIG choke. But it was similar maybe i didnt check its weight for a long time. BUT this morning it was 30,9 kilogrammes. Putting it in the rack was always a big task not so much because of the height but the limited space available AND the use of sorbothane dampers. What i do know is using 2 wooden bars and slide the dddac inside the rack. After that i use an inflatable cushion, pump it up, put the sorbothane dampers( the one that looks like half a tennis bal) in the right spot and then let the air escape. Works flawlessly because when the sorbothane are attached to the DDDAC in a permanent way you cannot slide it. Have to create some clearance and that is hard when there is only 5 centimeters in height extra available in the rack.
I replaced the frontplate with another stainless steel one and installed a very old panelmeter ( moving iron) to indicate the voltage going into the main print.
Now i will first finish some other things before modifying the DDDAC again.
First modification will be changing the Belleson 5 volt 2A supply for the wave IO. Right now it is choke input but i wanna try to use the 0,5 A LL2771 here.
I checked the voltage on that supply to find out what transformer i will need. When just thev wave IO is being fed by the power supply , so no signal connected will it still take 385 mA ? Right now the input of the Belleson is around 10,5 volts. Maybe i wanna change it into superteddyreg.
As you can see there is still some space left.
In the future i wanna switch to i2s gear but i still have my Aurender.
They say switching from usb to i2s is worth the trouble. The parts needed in the dddac are moderately priced but the strwamer sold by Audiocreative is not to cheap after already having bought the Aurender.
Greetings, Eduard
P.s i think in a few weeks time i will have two LL2733 1 Henry 0,7 A for sale. I used them as the second choke in a LCLC supply for 1A load. Not sure if they can take 1A when used as input choke. Because the maximum ripple is 120 volts for them they can take extra current when ripple is much lower as in DDDAC use
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Old 20th April 2019, 12:25 PM   #6870
schiirrn is offline schiirrn  Germany
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The airgap of the choke is set for a current. The amount of AC doesn't matter. Check the Lundahl datasheet for "recommended dc current" and "saturating current". Stay clear of saturating the core. If you wonder about the current draw of the Wave IO just measure it.


If weight is an issue remove the mains transformers, rectifiers and first LC and put them in an external case. That way the only AC in the signal part is the audio signal.
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