MQN

[TioFrancotirdor]

Have you heard that ...

Raspberry Pi 2 B+ has been released: (1GB RAM, Quad Core processor, 4xUSB and direct I2S out).

Additionally this:

"WINDOWS 10

For the last six months we’ve been working closely with Microsoft to bring the forthcoming Windows 10 to Raspberry Pi 2. Microsoft will have much more to share over the coming months. The Raspberry Pi 2-compatible version of Windows 10 will be available free of charge to makers.

Visit WindowsOnDevices.com today to join the Windows Developer Program for IoT and receive updates as they become available."

I am thinking whether such platform (Raspberry Pi 2) might be better platform than regular PC for music playback:
Pluses:
- Much cheaper than regular PC. Just 35$!!!
It seems that Windows 10 will support this platform. -> so I assume MQN will be available as well :)
- It is powerful enough. Quad Core 4x900mhz. People downclock their PCs to 800Mhz anyway.
- Cheaper PSU. Requires just one 5V strong and clean power supply instead of expensive full linear multivoltage 3.3V,5V,12V PSUs.
- No need for windows license

Minuses:
- ?

Considerations:
- Is the 1GB of RAM enough for music playback. Volumio will be available soon on this platform.
- Less noisy than regular PC?

[nige2000]

x64?

[TioFrancotirdor]

x64?

Still 32bit. x64 is a matter of time a believe. Does it make significant difference anyway?

I previously used to use Raspify on Raspberry Pi (current Volumio). I drop using Raspify becasue it did not supported spotify.
However in new volumio releases spotify is supported.

I think Raspify Pi 2 + volumio together with "USB Sonore" which has FPGA reclocking module on isolated clean side might be good match.
Much cheaper than regular PC with full linear multivoltage PSU 3.3V, 5V, 12V, PCI 3.0 USB card with sepearate clock and clock for motherboard.

Ideally Raspify 2 + Windows 10 + MQN would be ideal if 32bits is not the case.

[nige2000]

Thought MQN was 64bit maybe need SBGK to clarify
would be nice to have the whole thing standardised

can the pi2 take a clock input

I had a pi with Ian fifo reclocker it sounded quite good or as good as my audio pc running daphile
so knew it's sw that's bringing the magic not necessarily the hardware in pc's

there must be other win 10 devices suitable for this app too?

[seeteeyou]

Quad-core ARM Cortex-A7 = ARM architecture for sure. No AVX2 support, not x86, and not x64 so we're outta luck.

It's basically the same obsolete Windows RT stuff with a different moniker called Internet of Things (IoT) or Windows 10 "Athens" for this case.

The Windows 10 experience on Raspberry Pi 2 will likely be very similar to Windows RT - i.e. no desktop apps. However, Microsoft is doing the work to make sure that universal applications that run on the Surface Pro 3 also run on the Raspberry Pi 2.

http://www.anandtech.com/show/8953/rasp ... windows-10

AFAIK those universal applications are only limited to stuff designed for Metro

http://dev.windows.com/en-us/develop/bu ... ndows-apps

In other words, no foobar2000, no MQn, no JRMC, and no HQPlayer since they're all desktop apps built for x86 / x64 architecture for now. Maybe developers might bring them to Windows 10 for IoT for supporting both ARM and x86 simultaneously



However, we still have to deal with ASIO / WASAPI / Kernel Streaming support unless Microsoft is committed to bring USB Audio Class 2.0 to Windows 10 for IoT. Basically we could scratch RPi 2 off the list if the implementation of USB Audio were not working for USB DAC and DDC at all.

[sbgk]

mqn is 64 bit, can be compiled for 32 bit, ARM etc

[sbgk]

in case people hadn't seen this

http://www.audioasylum.com/forums/pcaud ... 26159.html

HI JE,
I'll try and give some real life examples here of how things other than "the bits" could have an affect on the analog output.

I've been working on a new USB DAC design recently, so I have a setup that I'm continuously looking at with scopes and logic analyzers etc. In this situation the logic analyzer said everything was fine, the bits were perfect. A logic analyzer runs the analog voltage on the wire through a "threshold" to distinguish if it is high or low, what you see on the screen is just high or low, ie "bits". But when I looked with the scope which shows the actual voltage levels of the signal I saw some extra signal riding on top of the highs and lows of the "bits". This turned out to be noise on the ground plane caused by the processor that was generating the bits. (it was much worse than it should have been due to a poor board layout of the processor reference board) That noise was enough to cause significant change to the audio out even though the "bits" were correct.

One interesting aspect of this was that you could easily see changes in this ground plane noise depending on what the processor was doing. While this was a fairly gross example of the effect, it clealy shows that things going on in the processing and transmission of the bits can have an affect on the sound at the output, even though the correct bits get to the DAC chip.

Next you might ask "well isn't that a broken system, if it was "good" shouldn't it not be an issue?" Note that this was the official reference board for the processor made by the manufacturer, who should know how to make things that work well with their processor. This just goes to show that things that can cause audible differences in digital audio are frequently not part of "it works as a digital system", the board did what it was supposed to, it delivered the bits.

A better board design could have cut this ground noise down significantly, but it would still be there.

What we DAC designers have to do is figure out ways to design products that produce analog out that is immune to this sort of thing. Unfortunately this is extremely difficult to do. There are many people on this board that expect that this is easy to do, just put in the right 50cent part and presto the design is completely immune to everything. It doesn't work that way. High frequency ground noise is extremly pernicious stuff, it will find a way to get around just about any obsticle you throw in its path.

Different designers take different approaches to try and achieve this with varying degrees of success. The different approaches will usually be affective at decreasing susceptibility to different types of noise so one DAC model may not care about a certain aspect (say cable differences) while another may be pretty immune to cable aspects but be susceptible to timing variations in packets. This may be a part of why some people say they can hear certain aspects and others say they cannot.

These techniques for noise suppression are pretty esoteric knowledge, there really are only a few people that really understand all this, there are very few places in the real world were the combined knowlege to make this really work right are required, thus very few people have a good grasp on all of this. The result is that many actual designs on the market are fairly lacking in this department, or are only targeting one aspect of it.

This is slowly changing and companies are starting to get an inkling of what it takes to do well with this and are hiring people with some knowledge in this field, but there aren't nearly enough to go around, so it's going to be some time before all digital audio systems you can buy do a good job in this regard.

Sorry, I'll get off my soapbox now.

John S.

[tony]

Down with this sort of thing, we all know the world is flat. Off with you over to PFM with that revelation and you will get the true 'facts'

[rickmcinnis]

What is PFM?

Swenson has all kinds of things to say like that but the reality is we are stuck with what we have and have to find out how to do the best with it we can.

I know Dave Daqvenport (RALEIGH AUDIO/K&K Audio) knows his grounding stuff and says he has incorporated some sophisticated techniques into his DAC board. Poured grounds; he has a paper on grounding , in general, at his site. http://www.raleighaudio.com/Audio%20Com ... ection.pdf - worth a read.

I have somewhere another of his papers - hope I have not lost it, that goes into his experiments with poured grounds which was from a conversation he had with Bud Purvine, who came upon this idea (the link is to someone who makes the things - http://tweakaudio.com/EVS-2/EVS_Ground_Enhancers.html) which is somehow an implementation of an instant poured ground. Seems to be something like an electron sink or source - an active ground? I am way over my head here!

Anyone looked into this? I have tried the product linked at my loudspeakers and it does add a bit of refinement to the sound.

Like sima was talking about: weird things that make the sound better.

[tony]

What is PFM?

I know Dave Daqvenport (RALEIGH AUDIO/K&K Audio) knows his grounding stuff and says he has incorporated some sophisticated techniques into his DAC board. Poured grounds; he has a paper on grounding , in general, at his site. http://www.raleighaudio.com/Audio%20Com ... ection.pdf - worth a read.

I have somewhere another of his papers - hope I have not lost it, that goes into his experiments with poured grounds which was from a conversation he had with Bud Purvine, who came upon this idea (the link is to someone who makes the things - http://tweakaudio.com/EVS-2/EVS_Ground_Enhancers.html) which is somehow an implementation of an instant poured ground. Seems to be something like an electron sink or source - an active ground? I am way over my head here!

PFM UK forum. Can be good as it is very broad but see link any warblings like yours above are met with great consternation and gnashing of teeth. :)
http://www.pinkfishmedia.net/forum/show ... p?t=168061

I see Swenson has a new dac with fpga,filters and also a battery supply pending(which he has found offers improvements)
http://bottlehead.com/product/bottlehead-dac/

I think we all would love to fully understand grounding and how best to deal with it. Do a bit of a search here and you will find Adam's work on this. He has the entreq system. One day I might try and arrange a trial with it. Adam has also gone to great lengths(literally) with grounding rods. Will read your link but looks like it will be well over my head also!