you measured the POS and NEG against COMMON or against each other? The latter case would be ok. measuring against COMMON I would expect 4 values of course like 2.7 2.8 Volt. check this first pls
Be careful!!
BE CAREFUL to use this as general tip... If your system's Ground (GND/Common) from DAC and Amplifier are connected through safety earth, you will effectively connect/short one output of the DAC to the Ground/earth system. This might work if your complete audio system is 100% floating from the safety ground. Results could be huge HUM and or total misalignment of the DAC bias up to damage of the DAC chips
BE CAREFUL to use this as general tip... If your system's Ground (GND/Common) from DAC and Amplifier are connected through safety earth, you will effectively connect/short one output of the DAC to the Ground/earth system. This might work if your complete audio system is 100% floating from the safety ground. Results could be huge HUM and or total misalignment of the DAC bias up to damage of the DAC chips
Hi all,
There is a new input option for the DDDAC! Dante!
AES67 – Dante™ AoIP Stereo Maker Boards – Micromedia AG
I have tried the Digimedia DIO RCA TOS. It comes with a I2S on board. With the virtual Soundcard Software from Audionate it pops up like a "normal" soundcard on Windows or Mac OS systems!
For me it runs on a MacBook with Roon and HQ Player. It sounds very natural. Great stage an more analog.
The invest? Around 200.- inkl. shipment plus the virtual soundcard software!
Greetings
Christian
There is a new input option for the DDDAC! Dante!
AES67 – Dante™ AoIP Stereo Maker Boards – Micromedia AG
I have tried the Digimedia DIO RCA TOS. It comes with a I2S on board. With the virtual Soundcard Software from Audionate it pops up like a "normal" soundcard on Windows or Mac OS systems!
For me it runs on a MacBook with Roon and HQ Player. It sounds very natural. Great stage an more analog.
The invest? Around 200.- inkl. shipment plus the virtual soundcard software!
Greetings
Christian
Hi All,
After all these years, I have recently been interested in 1794 DAC so finally went
through this thread - wow, that's a lot of work and the results look fantastic.
I have a couple of questions
- what is the purpose of using CCS for IREF?
There was some discussion over at TI and they recommended to connect R for
Iref directly to Pin 19 (A GND).
- By using 6k how much does OP current increase? Standard is +- 3.9mA / phase.
Looks like great DAC!
cheers
T
After all these years, I have recently been interested in 1794 DAC so finally went
through this thread - wow, that's a lot of work and the results look fantastic.
I have a couple of questions
- what is the purpose of using CCS for IREF?
There was some discussion over at TI and they recommended to connect R for
Iref directly to Pin 19 (A GND).
- By using 6k how much does OP current increase? Standard is +- 3.9mA / phase.
Looks like great DAC!
cheers
T
Thanks for the flowers
The CCS is giving the same current (4,0mA) but with a much higher resistance (thanks to the CCS as compared to the 6k resistor). This helps decouple the bias system and it sounds (indeed) better. simple trick, good result
as long as you have no hum this is a sign all is floating. So you will not hurt anything. but pls stay careful when changing things. Connecting other equipment or flipping the power cable 180degrees for example
Thanks for the flowers
The CCS is giving the same current (4,0mA) but with a much higher resistance (thanks to the CCS as compared to the 6k resistor). This helps decouple the bias system and it sounds (indeed) better. simple trick, good result
You are welcome
So higher impedance (resistance) appears to be more important than noise
per se, as the CCS will feed higher current noise into IREF which is
essentially a current IP point being of fixed voltage.
I'm just trying to understand the mechanism at work here - not to be critical.
Did you have 6k resistor terminated right on Pin 19 separate to ground plane
as recommended by TI?
T
You are welcome
So higher impedance (resistance) appears to be more important than noise
per se, as the CCS will feed higher current noise into IREF which is
essentially a current IP point being of fixed voltage.
I'm just trying to understand the mechanism at work here - not to be critical.
Did you have 6k resistor terminated right on Pin 19 separate to ground plane
as recommended by TI?
T
OK , let me give some background - probably interesting for the other readers as well -
The version 1 of the dac, as described on my website, has the 6k resistor. The CCS has been introduced in version 2. Many listening test showed improved sound quality. Similar improvements as in power supply improvements.
In terms of noise in the audioband, the S/N ratio from the current source noise ending up in the reference current is -107dB. The thermal noise of the 6k resistor delivers -110dB (at 1MHz for example it is -90dB versus -93dB)
I believe more important is the ~ -40dB damping the current source is giving on any power supply noise coming from pin 20 versus using a 6k resistor for the bias current. As the FET has less gain in higher frequencies, The point where the damping is equal to a ideal resistor is 22MHz. But truly, I do not thing a resistor has no inductance at that point playing an important role, so all in all, the CCS has clearly better performance in noise and power supply noise suppression in the bias current.
And most important, listening test unanimously shows that as well
The output signal current at 0dB signal at both outputs (POS and NEG versus Common) is +- 6,3mA peak.
You are welcome
Did you have 6k resistor terminated right on Pin 19 separate to ground plane
as recommended by TI?
T
Interesting thought of course to keep the loop as direct as possible. No, the return path has been in both versions on the ground plane, which is pretty solid and not too noisy in that corner of the PCB. So hard to tell if it would have made any difference...
anyone who would like to experiment, could try what is below in image.
In stead of soldering the 100Ohm resistor to GND, wire it directly to pin 19 (Analog GND) In this case there is no ground plane in the return path...
Attachments
I want to ask all of you who has the waveIo card if you have checked your system for white noise when volume is set to max. This last weekeend I have checked every bit of my dddac with separate psu and chokes. And it’s dead silent until i connect waveIo. To be absolutely sure
I called a friend and asked him to check out his waveIo too. IT seems that he also have this noise.
Is waveIo simple not inn the same league as our beloved dddac ?
I am exited to hear if others have this noise to.
(My wife could hear the noise 3m away from the speakers).
I called a friend and asked him to check out his waveIo too. IT seems that he also have this noise.
Is waveIo simple not inn the same league as our beloved dddac ?
I am exited to hear if others have this noise to.
(My wife could hear the noise 3m away from the speakers).
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The fact you attach the WaveIO means the DAC gets a clock signal and the Mash generator in the dac chip starts working. Before it did nothing, hence silent.
Now we had this discussion already a few years ago and you can read it on my website as well. DDDAC 1794 NOS DAC - Non Oversampling DAC with PCM1794 - no digital filter - modular design DIY DAC for high resolution audio 192/24 192kHz 24bit
The quantization noise at 44.1 kHz and 48kHz is audible when playing a silent track at full volume. If you play a silent track at 88 or above it is above the audio band.
If you are using a pre amplifier or Integrated amplifier with volume control. this is something which you will normally not notice when playing music
Now a question, are you using the DAC connected straight to an amplifier and using digital volume control?
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Ok Doede, I am a relative newbe, so please forgive me if I not completely understand.
When you say play a silent track I’m not shure what you mean. I can hear the noise when my Aurender is shut off. Waveio has dedicated choke-psu design. My friend told me that the nois was gone when he switch over to s/pdif on the mainboard. Can you explain why ?
Anyway my setup have never performed better, just curious.
I use SPEC PRA 7EX as pre-amp. It’s a very special design and I am not sure what kind of volume control it has.
When you say play a silent track I’m not shure what you mean. I can hear the noise when my Aurender is shut off. Waveio has dedicated choke-psu design. My friend told me that the nois was gone when he switch over to s/pdif on the mainboard. Can you explain why ?
Anyway my setup have never performed better, just curious.
I use SPEC PRA 7EX as pre-amp. It’s a very special design and I am not sure what kind of volume control it has.
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