I discovered in the meantime that my U34 was not functioning anymore, so mute was a problem anyhow. So I had to repair a bit.
Maybe it happened after installing this supporting circuit:
This circuit is necessay to battle a mistake in the original PCB design: When not streaming via the beaglebone, it stays on mute. But when you want to play via USB this is not good ofcourse. The above circuit actively pulls the beaglebone mute pin down when the USB cable is connected and the Amanero or Xing U30 is powered up.
Now I am almost satisfied. No pops at all during clock switches. The only remaining problem is that at powering on the DAC, at start of the first track, there is still a one time pop. When I look at the Xing U30, it shortly mutes also at starting the first track. The beaglebone mute function is not doing this. Maybe I should delay the DSD_ON by hardware, if the software stays this way.
Maybe it happened after installing this supporting circuit:
This circuit is necessay to battle a mistake in the original PCB design: When not streaming via the beaglebone, it stays on mute. But when you want to play via USB this is not good ofcourse. The above circuit actively pulls the beaglebone mute pin down when the USB cable is connected and the Amanero or Xing U30 is powered up.
Now I am almost satisfied. No pops at all during clock switches. The only remaining problem is that at powering on the DAC, at start of the first track, there is still a one time pop. When I look at the Xing U30, it shortly mutes also at starting the first track. The beaglebone mute function is not doing this. Maybe I should delay the DSD_ON by hardware, if the software stays this way.
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I have done some more listening. Changed my mind on the DSD512 preference with HQPlayer modulator. Overall I like ASDM7ECv3 the best. Sounds near pure perfection. I suspect that this type is very difficult to improve further. The super variants sound like they need further development.
With respect to Xing U30 vs beaglebone I like the beaglebone more. U30 is very good but gives less refinement. It adds a bit of fuzziness in direct comparison while beaglebone is super clean from the lowest to highest frequencies. Brings me closer to what I expect from the most true to original. And with ASDM7ECv3 you can hear this quite well.
With respect to Xing U30 vs beaglebone I like the beaglebone more. U30 is very good but gives less refinement. It adds a bit of fuzziness in direct comparison while beaglebone is super clean from the lowest to highest frequencies. Brings me closer to what I expect from the most true to original. And with ASDM7ECv3 you can hear this quite well.
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I implemented a support circuit, to have a safe first track with the BBG when the DAC is powered up. No pop because the DSD_ON is delayed when the stream starts.
It works as follows:
When DSD_ON is low (at first powering up of the DAC), pin 7 on U12 is high. The 4,7uF is quickly charged and U12 pin 5 is also high. The DAC is then muted.
When the DSD stream starts the first time after powering up, DSD_ON becomes high and U12 pin 7 becomes low. But U12 pin5 will only become low after the 4,7u has been discharged enough across the 22k1 resistor. This little delay is enough to prevent the big pop.
I think the DAC is now ready to be finalized. Only thing maybe is adding the DSD'it which I will do if my colleague really would like to have this functionality when I build the DAC for him.
It works as follows:
When DSD_ON is low (at first powering up of the DAC), pin 7 on U12 is high. The 4,7uF is quickly charged and U12 pin 5 is also high. The DAC is then muted.
When the DSD stream starts the first time after powering up, DSD_ON becomes high and U12 pin 7 becomes low. But U12 pin5 will only become low after the 4,7u has been discharged enough across the 22k1 resistor. This little delay is enough to prevent the big pop.
I think the DAC is now ready to be finalized. Only thing maybe is adding the DSD'it which I will do if my colleague really would like to have this functionality when I build the DAC for him.
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Last week i have done some work on this board.
This is what the current state is and is close to release.
What is done sofar.
Changed the name to Pure DSD dac DSC3
The Pin 15 mod is implemented (not tested) Jumper 6 will allow you to switch back to the old way of keeping pin 15 up.
The Beagle Bone was not able to be used when de Amanero was plugged inn. That is the circuit from post 2082
The USB interface was not working without BB connected. The BB is supplying the 3.3V for the isolator and the mute chips.
With Jumper 4 it is possible to use the 3.3V from the Amanero for that.
The mute during powering up was not on hat resoled in noise and plopt during the boot. the circuit from post 2086 solves that.
Jumper 7 is for selecting the mute that can be used from the Amanero. In DSD mode the DSD on can be used. When using PCM with the DSDit the 3.3V wil select the Amanero.
Jumper 5 will allow you select the mute from the BB pin 27 or default pin 28.
We found that the U23 and U33 was powered on pin 5 and the data sheet specify pin 6 for the power so that is changed.
We removed the mounting holes for the Nazar and the extra connectors for that.
The option for the larger transformers is removed, the metal case of the T2 transformers was creating a short circuit on the connection holes.
The fuse on the power input is removed, Pleas use fuse in the power line to the bord.
That was it for now.
If you see some strange things please let me know.
This is what the current state is and is close to release.
What is done sofar.
Changed the name to Pure DSD dac DSC3
The Pin 15 mod is implemented (not tested) Jumper 6 will allow you to switch back to the old way of keeping pin 15 up.
The Beagle Bone was not able to be used when de Amanero was plugged inn. That is the circuit from post 2082
The USB interface was not working without BB connected. The BB is supplying the 3.3V for the isolator and the mute chips.
With Jumper 4 it is possible to use the 3.3V from the Amanero for that.
The mute during powering up was not on hat resoled in noise and plopt during the boot. the circuit from post 2086 solves that.
Jumper 7 is for selecting the mute that can be used from the Amanero. In DSD mode the DSD on can be used. When using PCM with the DSDit the 3.3V wil select the Amanero.
Jumper 5 will allow you select the mute from the BB pin 27 or default pin 28.
We found that the U23 and U33 was powered on pin 5 and the data sheet specify pin 6 for the power so that is changed.
We removed the mounting holes for the Nazar and the extra connectors for that.
The option for the larger transformers is removed, the metal case of the T2 transformers was creating a short circuit on the connection holes.
The fuse on the power input is removed, Pleas use fuse in the power line to the bord.
That was it for now.
If you see some strange things please let me know.
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Thanks i will check the link.
Here is the correct part
https://nl.mouser.com/ProductDetail/CK/TDA02H0SB1R?qs=/NF5U5UGuWn3xddlBViRrw==
There are more parts where the link is not working.
I have not used the links in the bom and the parts that have a link are in there from the past.
The part numbers are more relevant and let you find the part at your favoriete supplier.
We ware able to get the majority of the parts at Mouser.
Here is the correct part
https://nl.mouser.com/ProductDetail/CK/TDA02H0SB1R?qs=/NF5U5UGuWn3xddlBViRrw==
There are more parts where the link is not working.
I have not used the links in the bom and the parts that have a link are in there from the past.
The part numbers are more relevant and let you find the part at your favoriete supplier.
We ware able to get the majority of the parts at Mouser.
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The part number for the resistor networks is what?
According to the BOM it says:
SOIC-16_3.9x9.9mm_P1.27mm
Vishay
Don't know what part number that refers to.
Actually it looks like various parts are not well defined. Might be hard for people to figure out what parts fit the PCB layout.
For example, not clear on a part number for a heatsink. Or maybe R70, R71? Wattage, tolerance, etc.?
According to the BOM it says:
SOIC-16_3.9x9.9mm_P1.27mm
Vishay
Don't know what part number that refers to.
Actually it looks like various parts are not well defined. Might be hard for people to figure out what parts fit the PCB layout.
For example, not clear on a part number for a heatsink. Or maybe R70, R71? Wattage, tolerance, etc.?
Hello Geosto!
I'm glad you put in the effort to make your DSC 3 layout awesome!
I have some small suggestions about the diagram as follows:
1) power supply for 3.3(a) and 3.3(b), should be separated into 2 separate sources, to avoid cross-channel interference. LP5907MFX can be used instead of LT3042. The power source for CCHD 957 using LT3042 works as stably as possible. Power supply for BBB can also replace TPS54332 with LT1963 this part I think is not very important
2) Simultaneous layout For CCHD 957 with NDK NZ2520SDA there are 2 options.
Best regards!
In next ten days I'm finishing single ended DSC version with discrete i/v, multifeedback filter, tone control with discrete resistor based potentiometers i2c controled, single ended to diff, it will be dac/preamp for UCD180HxR. Power supply is specialy designed push pull high voltage preregulator suplied directly from +HV of the smps400a180 from Hypex, the three small super regulators is Jung Didden discrete version, +15V, -15V, +5V, it will supply dsc, I will show you all when finish them.
Attachments
![DSC_2169[1].jpg](/community/data/attachments/1105/1105752-805b3a03dd83842e9504769e74e9a2cc.jpg)
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