Did you power RPi from the non-isolated GPIO? Is it better than power from USB?
Your 502DAC looks very cool
Ian
I did power Rpi from non-isolated GPIO, and it is a bit better than power from USB. But the real leap in sound quality happens when I desolder the built-in SMPS on Pi, and power Pi with 3,3V and 1,8V from 2 PSU boards using LT3045.
In conjunction with your IsolatorPi, the sound rights now is great. The first things I perceive is, sound in low volume right now is very clear, with so much nuances, better timbre and microdynamic. The loud tuttis in some orchestral pieces are still very loud, but with more separation between instruments. More importantly, through the whole spectrum, sound is free of harshness, which I sometimes perceived with my old Pi setup (Pi + 502DAC + iFi iPower).
The 502DAC have built-in LT3042 PSU, which converts 5V to 3,3V, to feed PCM5122, WM8804 and NDK clocks. The other pieces in my setup is Schiit Gungnir Multibit and JBL LSR305s
In conjunction with your IsolatorPi, the sound rights now is great. The first things I perceive is, sound in low volume right now is very clear, with so much nuances, better timbre and microdynamic. The loud tuttis in some orchestral pieces are still very loud, but with more separation between instruments. More importantly, through the whole spectrum, sound is free of harshness, which I sometimes perceived with my old Pi setup (Pi + 502DAC + iFi iPower).
The 502DAC have built-in LT3042 PSU, which converts 5V to 3,3V, to feed PCM5122, WM8804 and NDK clocks. The other pieces in my setup is Schiit Gungnir Multibit and JBL LSR305s
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Trung224,
Very, very nice! Thanks for sharing!
So you feed S/PDIF to the Gungnir? It didn't look like you were taking analog from the 502DAC.
Can you post pix of your RPi power feed mods? Very interested in trying this!
Thanks!
Greg in Mississippi
Thanks Greg,
I am using Gungnir Multibit as DAC. 502DAC outputs SPDIF to Gumby via BNC. Analog out from 502DAC is not bad, but definitely inferior to Gumby as DAC.
Here is my power mod
Firstly, I desolder a SMPS, which converts 5V from GPIO (or mini USB) to 3,3V and 1,8V.
after desoldering
I have two LT3045 PSUs, which output 3,3V and 1,8V respectively. I solder 3,3V PSU to PPM8 and 1,8V PSU to PPM9 as you can see
After that I feed 5V from my AMB Sigma 11 to RPi through GPIO pin 2 in non-isolated GPIO in Isolator Pi.
All GND of three PSUs are connected GPIO pin 6 in non-isolated side of IsolatorPi (or RPi).
The isolated side of IsolatorPi and 502DAC are fed by Salas reflektor mini (output 400mA), but it is not important, as 502DAC has its own LT3042 PSU. I think the most important is getting rid of SMPS and feeding RPi by LT3045 PSUs, which have very strong PSRR, even in high frequencies
I am using Gungnir Multibit as DAC. 502DAC outputs SPDIF to Gumby via BNC. Analog out from 502DAC is not bad, but definitely inferior to Gumby as DAC.
Here is my power mod
Firstly, I desolder a SMPS, which converts 5V from GPIO (or mini USB) to 3,3V and 1,8V.
An externally hosted image should be here but it was not working when we last tested it.
after desoldering
An externally hosted image should be here but it was not working when we last tested it.
I have two LT3045 PSUs, which output 3,3V and 1,8V respectively. I solder 3,3V PSU to PPM8 and 1,8V PSU to PPM9 as you can see
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
After that I feed 5V from my AMB Sigma 11 to RPi through GPIO pin 2 in non-isolated GPIO in Isolator Pi.
An externally hosted image should be here but it was not working when we last tested it.
All GND of three PSUs are connected GPIO pin 6 in non-isolated side of IsolatorPi (or RPi).
The isolated side of IsolatorPi and 502DAC are fed by Salas reflektor mini (output 400mA), but it is not important, as 502DAC has its own LT3042 PSU. I think the most important is getting rid of SMPS and feeding RPi by LT3045 PSUs, which have very strong PSRR, even in high frequencies
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@trung224
I like your powering approach.
How about replacing Rpi3 with Pi Zero. It should have even less noise. It also consumes less power (around 100ma with volumio) in such case you could use Salas Ref D 5V instead of AMB Sigma 11, lt3045-3.3v, lt3045-1.8V for powering the Pi Zero.
I like your powering approach.
How about replacing Rpi3 with Pi Zero. It should have even less noise. It also consumes less power (around 100ma with volumio) in such case you could use Salas Ref D 5V instead of AMB Sigma 11, lt3045-3.3v, lt3045-1.8V for powering the Pi Zero.
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@trung224,
Many thanks for the details and detailed pictures. I plan to try this in the next few weeks. Thinking about it, I was surprised that the 3.3V & 1.8V rails can be supplied by the 500mA max LT3045 regulators... very good though. I have plenty of ADM715x-based boards here which will supply 800mA, I'll try some of them.
Thinking about how to implement this, I like how you are feeding the 5V into the RPi via the expansion header, which is how I generally power my Pi setups. I may also feed the 3.3V here too. Pity they didn't include a 1.8V pin!
Again, thanks!
Greg in Mississippi
Many thanks for the details and detailed pictures. I plan to try this in the next few weeks. Thinking about it, I was surprised that the 3.3V & 1.8V rails can be supplied by the 500mA max LT3045 regulators... very good though. I have plenty of ADM715x-based boards here which will supply 800mA, I'll try some of them.
Thinking about how to implement this, I like how you are feeding the 5V into the RPi via the expansion header, which is how I generally power my Pi setups. I may also feed the 3.3V here too. Pity they didn't include a 1.8V pin!
Again, thanks!
Greg in Mississippi
@TioFrancotirador : Thanks for your advices. I don't think I will use Pi zero. It is probably better than my RPi 2 in terms of noise. But it doesn't have ethernet connector, which I think is a must for stable streaming HiRes files.
About skipping 3.3V from LT3042 to AVDD of 502DAC and powering it directly from Salas Reflektor D, it is very good idea. But, by doing so, we will make a trade off between local regulator (better signal road, low res) with better external regulator (assuming Salas Ref D is better than LT3042 PSU). Personally, if local regulator is good enough, and LT3042 is a really good one, I won't change it.
@Greg Stewart
You should be careful when trying to feed 3.3V to RPi via GPIO. I think I have read somewhere that you shouldn't put too much current through 3.3V GPIO, otherwise it will damage RPi.
About skipping 3.3V from LT3042 to AVDD of 502DAC and powering it directly from Salas Reflektor D, it is very good idea. But, by doing so, we will make a trade off between local regulator (better signal road, low res) with better external regulator (assuming Salas Ref D is better than LT3042 PSU). Personally, if local regulator is good enough, and LT3042 is a really good one, I won't change it.
@Greg Stewart
You should be careful when trying to feed 3.3V to RPi via GPIO. I think I have read somewhere that you shouldn't put too much current through 3.3V GPIO, otherwise it will damage RPi.
Ian: After more experimenting, slave mode with kali/piano works... still no audio power LED, so partially working.
Hifiberry DAC+ PRO, Allo Boss, pi2media does *not* work on this board... whereas it does on the other.
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If you are referring to the DOP setting in Volumio, it is set, if not please point me in the right direction thanks
From the picture, if one LED is on, the other LED is off, that means the isolator side doesn't have power.
Ian
Hi sckamer,
Just realized one is working the other isn't. Try to remove the u.fl socket at the wrong position if that is the bad one. I'll send you a new one if you still can not make it a work.
Regards,
Ian
It looks like you are applying power to both the Kali and Isolator? I found the if I feed power to the Kali, with the 'Feed SBC' jumper in place, then power is sent to the Isolator and it all works and the Isolator power LED lights up.
He is, but the jumper to pass power from the Kali to the 'SBC' (and hence isolator) is open.
Yes, I didn't notice that.
If I apply power to Kali only, with the jumper open, the Isolator power LED lights dimly and there is 1.8V present at the Isolator power block. Seems a bit odd?
I received my RPI isolator HAT and DOP decoder today. The package arrived to Finland already on monday, but the local post office was a bit slow. I'm planning to set up a rpi - isolator - KALI - DDDAC combination once I have the time - possibly during weekend. The DOP decoder is reserved for future use in case there will be any metal music in DSD format...
Thank You so much Ian for making these wonderful DIY things happening!
Thank You so much Ian for making these wonderful DIY things happening!