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Open-source USB interface: Audio Widget
Open-source USB interface: Audio Widget
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Old 31st December 2011, 12:52 PM   #751
borges is offline borges  Norway
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Hi John,

leave the USB VBUS connected to the MCU. There are some USB pull-up issues which may hit you if you cut it.

BÝrge
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Old 31st December 2011, 12:55 PM   #752
borges is offline borges  Norway
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Default Playback - Actual sample rate

There seems to be some confusion as to which players / OSes actually perform sample rate conversion and which are bit perfect.

Banshee, the default player in my Ubuntu installation kept the word clock at 44.1 with 192 content.

Can someone please suggest a player for Linux and explain to a Linux noivice how to set and check the sample rate in the OS and player?

I'm throwing out Ubuntu for Linux Mint by the way. I can't find anything in the GUI...


BÝrge
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Old 31st December 2011, 12:56 PM   #753
johnm is offline johnm  United Kingdom
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Quote:
Originally Posted by borges View Post
Hi John,

leave the USB VBUS connected to the MCU. There are some USB pull-up issues which may hit you if you cut it.

BÝrge
Won't this result in the USB 5v supply polluting the cleaner supply? Which means the new supply wouldn't actually be worth using? Sorry for all the newbie type questions )

- John
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Old 31st December 2011, 12:59 PM   #754
borges is offline borges  Norway
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Hi John,

look at the module sch and ab sch at the same time and see how the VBUS / VDD is set up

VBUS is sent down to the AB to be filtered etc. before entering VDD to the module LDO. The MCU needs to _sense_ VBUS but is not powered by it. A few posts back I linked to a conversation I had with Atmel support about this.

BÝrge
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Old 31st December 2011, 01:01 PM   #755
UnixMan is offline UnixMan  Italy
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Originally Posted by alexlee188 View Post
Again, PurePlayer somehow sounds better than FooBar2000. But maybe it's my imagination - it is just not as good as playing under Linux :-)
the only way to get a chance for decent sound from windoze is by-passing as much of it as possible... that is, using ASIO.

(and possibly removing/disabling as much of the OS as possible, too. That is, "cMP≤". Then of course one may ask why not use Linux instead... but that's another story. ).

IMO the only open-source windoze driver effort that may make sense would be an UAC2 ASIO driver.

Such a driver will never happen from M$, and it is unlikely that anyone else would release one which is not tied to some specific hardware.

Oh, ASIO4ALL is not an option. Reportedly the sound with it is nowhere near that of a "true" native ASIO driver (of course that was tried with hardware which allows both options, such as Asus Xonar Essence, etc).
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Last edited by UnixMan; 31st December 2011 at 01:16 PM.
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Old 31st December 2011, 01:11 PM   #756
UnixMan is offline UnixMan  Italy
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Originally Posted by johnm View Post
sometimes sound a little 'sharp' and lacking in body.
second. Replace the OsCons with Elna Silmic II of higher values (at least 100uF, possibly more), add the missing caps on the supply lines and that will be fixed even on USB power.

Oh, do NOT forget to use an USB cable with ferrite beads on it. That's paramount for SQ.
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Old 31st December 2011, 01:17 PM   #757
johnm is offline johnm  United Kingdom
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BÝrge: Ahaa I see what you mean now Super! I'll get modding later today then! Thank you.

UnixMan: Interesting - I'll try that. In regards to the supply lines, do you mean cap positions: C21/31/28?

Already using the ferrite beads - Surprising how clean the stock PSU is actually. It just needs a touch more solidity/body to sound REALLY good. Hopefully the mods you mention plus my PSU will help
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Old 31st December 2011, 01:29 PM   #758
UnixMan is offline UnixMan  Italy
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Quote:
Originally Posted by borges View Post
Banshee, the default player in my Ubuntu installation kept the word clock at 44.1 with 192 content.
there is an almost countless number of players, most of which are good. For simple/easy/light I can suggest the already mentioned "gogglesmm" or "audacious". But "banshee" is just perfect. It's not the player that matters!

Most modern Linux desktop distributions (including Ubuntu) have adopted "pulseaudio", an audio "middleware" which takes care of handling different audio inputs and outputs, mixing and/or routing the different streams, etc.

Of course, that requires that all the streams MUST be resampled to a single, common s/r. This is what is normally done also by the windoze audio stack, for the very same reasons. In windoze the solution is to by-pass everything and use ASIO.

In Linux, the simple and definitive solution is to get rid of pulseaudio. Just unistall it:

Code:
apt-get purge pulseaudio
and instruct whatever player you like to directly use ALSA instead.

BTW: for really best SQ, do use "Voyage MPD" Linux on a dedicated player machine and control it remotely using something like "GMPC". The Voyage MPD optimized kernel does make some difference WRT stock general purpose kernels. The light and clean environment with a minimum of extra processes likely helps, too.
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Last edited by UnixMan; 31st December 2011 at 01:36 PM.
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Old 31st December 2011, 01:36 PM   #759
Onvinyl is offline Onvinyl
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Quote:
Originally Posted by borges View Post
There seems to be some confusion as to which players / OSes actually perform sample rate conversion and which are bit perfect.

Banshee, the default player in my Ubuntu installation kept the word clock at 44.1 with 192 content.

Can someone please suggest a player for Linux and explain to a Linux noivice how to set and check the sample rate in the OS and player?

I'm throwing out Ubuntu for Linux Mint by the way. I can't find anything in the GUI...


BÝrge

You can always check under /proc/asound/card0/<yourcard> at which bit depth and sample rate your cards works actually.

Linux is like Lego, so you can take care by yourself. A first measure would be to use hw instead of plughw, so alsa would not resample anything by itself.

I use mpd, a music server daemon that could run on a headless machine and could be controlled by numerous devices including browser plugins or smartphone apps. You can chain it to convolvers or other DSP software if you like. The howto and example config files are (almost) self explanatory.

RŁdiger
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Old 31st December 2011, 02:28 PM   #760
starn02 is offline starn02  Italy
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My "extremely personal" experience with WinXP and "custom made" UAC2 drivers .... and with foobar2000: everything is OK, sample rates are all accepted and played without problems. Sound quality is constantly high, with hard to hear differences when upsampling (with SOX plugin) from 44.1 to whatever else.

"Reasonable" behaviour (not perfect, some little delay and sometimes hic up, but perfectly tolerable) when switching songs, and even when changing the upsampling rate while playing.

From what I read (on the forum) and see (on my setup) the firmware should be quite OK since the versions of Chrystmas .... if you have so much problems maybe the reason is in the PC / OS / driver ....
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