1 Topic by koscso (edited by koscso 2017-03-19 16:00:06)

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Topic: ADI 2 Pro - problem playing back extreme high-res (Ubuntu)

I am using a dual machine audio playback system with my ADI 2 Pro where Hqplayer on my Macbook Pro is feeding an Ubuntu - based ARM CPU driven nano PC using Hqplayer's NAA solution. The NAA app runs on the Ubuntu - based Cubox (Hummingboard) SoC. When i am trying to playback upconverted files above 384 kHz (up to 768 kHz) or DSD 128x (up to DSD 256x) there is some strange noise repeatedly, in every 30-40 sec for 3-5 sec. It happens in 704 and 768 kHz and 44x 256, 48kHz x 256 in DSD as well, in a different way however.

I tried all sorts of other D/A converters, none shows the same problem, so I think it is related to ADI 2 Pro and its firmware or someway the relationship of it to ALSA. Otherwise the ADI 2 Pro unit sounds really nice, I like it a lot, there is a very limited chance to use it at those very high sampling rates, but it would be nice to get it work there too.

2 Reply by MC

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Re: ADI 2 Pro - problem playing back extreme high-res (Ubuntu)

The other D/A converters most probably did not use 768 kHz. I fear the buffer size in ALSA is not big enough at that sample rate. Nothing we can fix on our side...

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Matthias Carstens
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3 Reply by koscso (edited by koscso 2017-03-20 10:58:03)

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Re: ADI 2 Pro - problem playing back extreme high-res (Ubuntu)

MC wrote:

The other D/A converters most probably did not use 768 kHz. I fear the buffer size in ALSA is not big enough at that sample rate. Nothing we can fix on our side...

Thx for the answer.
Actually I tried the iFi micro iDSD converter in exactly the same NAA/Cubox system, which does 768 kHz and even 512x DSD and it works without a problem as a native DSD device as well, without DoP implementation. The smaller and cheaper iFi micro iDAC2 works at 384 kHz and works in 256x DSD, it can not do 768k, but it is spec'd this way so not a problem.

So I think it should not be an ALSA problem only.

4 Reply by MC

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Re: ADI 2 Pro - problem playing back extreme high-res (Ubuntu)

The ADI-2 Pro works perfectly at 768 kHz with both Mac OS X as well as an iPhone and iPad. That is our Class Compliant reference.

There may well be small differences between the ifi unit and ours. We have 2 channels AD = recording, which under Mac/iOS always run in parallel to playback. And we use smaller internal bufffers on bus level to optimize low latency applications.

Anyway, we will try to test this under Linux to see if there is something we can do.

Regards
Matthias Carstens
RME

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Re: ADI 2 Pro - problem playing back extreme high-res (Ubuntu)

Many thanks for your investigation.

MC wrote:

The ADI-2 Pro works perfectly at 768 kHz with both Mac OS X as well as an iPhone and iPad. That is our Class Compliant reference.

There may well be small differences between the ifi unit and ours. We have 2 channels AD = recording, which under Mac/iOS always run in parallel to playback. And we use smaller internal bufffers on bus level to optimize low latency applications.

Anyway, we will try to test this under Linux to see if there is something we can do.

6 Reply by MC

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Re: ADI 2 Pro - problem playing back extreme high-res (Ubuntu)

We set up our Ubuntu machine and tested 768 kHz playback via HQPlayer. Zero problems. I don't know why the iFi works on your setup, but in general it seems the machine or its configuration is the problematic part here.

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Matthias Carstens
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Re: ADI 2 Pro - problem playing back extreme high-res (Ubuntu)

MC wrote:

We set up our Ubuntu machine and tested 768 kHz playback via HQPlayer. Zero problems. I don't know why the iFi works on your setup, but in general it seems the machine or its configuration is the problematic part here.

Thx for trying to replicate my problem.
Let me repeat, what I have written about the setup where I got the problem:

I do not use Ubuntu as such, I use the Hqplayer - NAA combo in a two machine setup: Roon streams to Hqplayer on my Macbook Pro, then I run NAA as a kind of Ethernet - USB bridge on my Cubox and Hummingboard SoC.

I have made two short videos of the problem with my mobile phone, you can see them here:

DSD 256x:
https://youtu.be/hCKIsoDSDRE


It does not matter if I use original 768 kHz or 256x DSD or upconverted version, the problem remains the same.
No other DAC I tried showed this.

Thanks for thinking with me.

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Re: ADI 2 Pro - problem playing back extreme high-res (Ubuntu)

The other link:

PCM 768 kHz:
https://youtu.be/mCgRvg3x5Ls

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Re: ADI 2 Pro - problem playing back extreme high-res (Ubuntu)

Would be cool if you would mention the version of Ubuntu and its relevant software packages.
Like i.e. which ALSA version etc etc ...
If somebody wants to troubleshoot then this is useful / required information.

BR Ramses - UFX III, 12Mic, XTC, ADI-2 Pro FS R BE, RayDAT, X10SRi-F, E5-1680v4, Win10Pro22H2, Cub14