Rapsberry PI3+ and smsl sanskrit pro B / strong noise with usb B2 connection

[rdbdb]

Hi everybody,

I’d made with an Rpi3 a Volumio platform.

Firstable, I’d use a DragonFly (black one) DAC to connect to my amplifier (Denon UHC) without any trouble. (USB Rpi to Dragonfly, jack 3.5mm to RCA).

But I’d would like to connect my Rpi3 “Volumio” to my Sanskrit pro-B by the USB-B 2 port input.
And then…big parasite noise !!!
I’d change the usb cable, but no result.

Do I need change anything on Volumio settings (it recognize the sanskrit pro-B) ?
Other idea ?

Thanks a lot.

For more information about this model:

S.M.S.L Sanskrit pro: up to 24-Bit at 384 kHz, DSD64 and 128, Bluetooth aptX,...

[EdW]

Is the DAC working? I.e. is the audio output approx same as with your Dragonfly? Is it undistorted? You need to do some diagnosis

What is the nature of the USB noise? Broadband hiss or high frequency tones or low frequency mains hum?

Is the DAC OK when fed with Toslink signal from TV? This checks whether the DAC is OK.

Does the DAC (running Toslink) get noisy when connected to the USB of the RPI? This would suggest that the DAC is extremely susceptible to USB noise from the RPI.

Using the DAC on other USB ports on the RPI - do they all have the same issue?

Hum would suggest a ground loop problem or faulty RCA leads from the DAC to amp

[rdbdb]

Hi and thanks a lot for your help.

@EdW

Is the DAC working? I.e. is the audio output approx same as with your Dragonfly? Is it undistorted? You need to do some diagnosis
Rpi works great with Dragonfly.
No sound of music with the SMSL sanskrit by USB B, only big noise

What is the nature of the USB noise? Broadband hiss or high frequency tones or low frequency mains hum?
Very High sound, Hi frequency.
Is the DAC OK when fed with Toslink signal from TV? This checks whether the DAC is OK.
Yes Dac is ok with Toslink.
Does the DAC (running Toslink) get noisy when connected to the USB of the RPI? This would suggest that the DAC is extremely susceptible to USB noise from the RPI.
No, nothing change, the sound happens only when I select the USB B source.

Using the DAC on other USB ports on the RPI - do they all have the same issue?
I’d tried with my Macbook, everything works without noise on the DAC.
I’d tried with the 4 ports of de Rpi, same problem with DAC.

Hum would suggest a ground loop problem or faulty RCA leads from the DAC to amp

[EdW]

So we have:
RPI driving Dragonfly USB DAC - works.

When the Sanskrit DAC is used it is powered by its own separate power supply not via the USB port in all cases? (The RPI might not be capable of supplying the necessary current if the power came via the USB port). Is the Sanskrit DAC powered before the RPI is powered? Not sure this matters since you say the Volumio software is recognising the DAC.

Mac driving Sanskrit DAC via USB - works. So the Sanskrit DAC is working via its USB. (What streaming software are you using on Mac?)
RPI driving Sanskrit DAC via USB port running Volumio (which version? Volumio would probably need this information to help) results in a complete malfunction. The DAC and the RPI aren’t communicating to each other correctly. USB cable isn’t the fault since swapping cables doesn’t fix the problem.

There seems to be some difference in the way the Mac and the RPI communicate to the Sanskrit DAC via USB. Unfortunately my experience is in hardware not software so I think we need another site visitor or the Volumio team to offer some advice here. Sorry I can’t offer more ideas right now

[rdbdb]

@EdW

So we have:
RPI driving Dragonfly USB DAC - works.
Yes

When the Sanskrit DAC is used it is powered by its own separate power supply not via the USB port in all cases? (The RPI might not be capable of supplying the necessary current if the power came via the USB port). Is the Sanskrit DAC powered before the RPI is powered? Not sure this matters since you say the Volumio software is recognising the DAC.
I’m agree

Mac driving Sanskrit DAC via USB - works. So the Sanskrit DAC is working via its USB. (What streaming software are you using on Mac?)
For the test, I’d cast a you tube video, and change the destination of sound by The Midi application on my Mac.
RPI driving Sanskrit DAC via USB port running Volumio (which version? Version 2.861 Volumio would probably need this information to help) results in a complete malfunction. The DAC and the RPI aren’t communicating to each other correctly. USB cable isn’t the fault since swapping cables doesn’t fix the problem.
Yes

There seems to be some difference in the way the Mac and the RPI communicate to the Sanskrit DAC via USB. Unfortunately my experience is in hardware not software so I think we need another site visitor or the Volumio team to offer some advice here. Sorry I can’t offer more ideas right now
I think you’re maybe right. I will try to update first the firmware of USB port software, and if it doesn’t work more, I will try to make some change in Rapsbian to send the audio signal directly to the DAC without treatment by de sound card of the Rpi. The objective is to use the external sound card of the DAC instead of the internal card. But I’m not convince…
But the difference between SMSL DAC and Dragonfly is the power supply: Dragonfly use usb power of the Rpi, and SMSL use his own power supply. Maybe there is a conflict with that when I use the smsl DAC, but not problem with the Mac…so…I really don’t know :-)…

By the way, many thanks to try to help, and welcome to other specialist to help me

[EdW]

Only just one other suggestion. If you have a spare SD card you might just try Moode.