Something cool for Raspberry Pi/ODROID: I2S/DSD isolator HAT with native DSD decoder

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#382
Dear forum members,

Earlier I used AKM 4137 Pi-HAT , and connected to my 4xTDA1543DAC. Unfortunately few days ago, the the Pi-HAT died, when I connected my DAC directly to the PI-s I2S pins, I realized the Noise, and THD immediately dropped by 10 dB.
For learning purposes I started to design an I2S Isolator HAT for my Raspberry Pi to reduce the noise. I have some questions regarding my project.
- For powering the clean side of the isolator (IL715, or ISO7640) I would like to use ADM7150LDO. Is it necessary to reach the lower noise, or can I use another cheaper but more noisy regulator?
- I've also added a +5V GNDD connector to powering the Pi via GPIO. I also want to add some protection, because the GPIO port doesn't have. I put a 1A1 6V resetable fuse into my circuit, but the checking the schematic of the raspberry, on the usb side they used an avalanche diode between the +5V and GNDD. Is it necessary? I don't want to add additional noise.

Thanks
 
#384
I read members here claim that with this setup where rpi --> isolatorpi --> Kali reclocker --> Boss DAC or 502DAC, the sound quality improves further compared with only using isolatorpi alone without Kali reclocker. Why the reclocker is not redundant since the DACs are running in master mode asynchronously and have good clocks built in? If to use the reclocker, is it not the Dac has to run in slave mode and bypass its own clocks? Are you saying the reclocker's clocks are better than the dacs' clocks?
 
#386
I think members here have enough experience and I will give them the benefit of the doubt. I am not worry about ABX test but I am more curious about why with isolatorpi in place, reclocker or FiFo board still needed since DAC hat already has good clocks implemented.
 
#388
Hello Everyone,

I've got a question. Is it possible to connect the mclk of the FifoPi with the Evo DAC Two Plus as external clock? See chapter 7.9 from the user manual for the https://lnx.m2tech.biz/wp-content/uploads/2017/06/Evo-DAC-Two-Plus-User-Manual-PrA.pdf for a description. If it is possible how will I overcome the difference in impedance? mclk of the FifoPi has an impedance of 50 ohm but the bnc connector on the Evo DAC Two Plus has an impedance of 75 ohm. I hope someone is able to answer my question.

With regards, Big Bird
 
#389
big bird said:
Hello Everyone,

I've got a question. Is it possible to connect the mclk of the FifoPi with the Evo DAC Two Plus as external clock? See chapter 7.9 from the user manual for the https://lnx.m2tech.biz/wp-content/uploads/2017/06/Evo-DAC-Two-Plus-User-Manual-PrA.pdf for a description. If it is possible how will I overcome the difference in impedance? mclk of the FifoPi has an impedance of 50 ohm but the bnc connector on the Evo DAC Two Plus has an impedance of 75 ohm. I hope someone is able to answer my question.

With regards, Big Bird
Click to expand...

https://lnx.m2tech.biz/wp-content/uploads/2017/06/Evo-DAC-Two-Plus-User-Manual-PrA.pdf
 
#390
Hifiberry Dac+pro power up

Just taken delivery of isolator2.

So to double check I have thos correct..

Move jumpers to enable master mode

Apply audio power in which will power the dac through isolated gpio

Apply power to rpi power input on iso2 which will then power the Rpi.

Is this the best way to do it ?

Regards
 
#393
So I had a quick rig up yesterday. Powered the pi with the existing smps into the pi for now....and a powebank into the audio 5v in on the Iso.

Took some attempts to work. DAC had booted but I got some Alsa fail messages in moode. It eventually worked.

But i got a lot of noise through the speakers along with the music. I soon turned it off.

Any pointers before I have another try?
 
#398
Greg thanks for the follow up and also apologies for not keeping my side of things up to date.

On the other thread I noted that I still have same noise issue ...but only with Moode. When I cast Spotify it is fine.

I haven't pursued it of late as I have been awaiting some of XRK971S psu boards. I shall power with these and see if any change.

I do need to build the boards though. Things happen slowly at my end.!

I can't understand why Moode is noisy but Spotify isn't. All same system.

Thanks again.
 
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#399
Hi Greg and Anyone,

I have got one Boss dac and if I want to get Ian's boards to improve its sound, could I use a Fifopi or Isolatorpi? I would prefer to use Fifopi since it has reclocking function and I am thinking to use 22/24 clocks. If it is Fifopi, is it just to connect Boss dac board on top of Fifopi? Is the ESS controller not needed because it is only working with ESS dac?
 
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