Linux Audio the way to go!?

[soundcheck]

Remains the question, what's wrong - what's right?

[phofman]

Well, considering cdparanoia is many years old and clearly flawed, EAC is the one more credible to me.

[nyc_paramedic]

First, hello to all on this thread. Secondly, I did read almost every single post in this thread, but forgive me in advance if something I refer to was already mentioned.

I am not new to Linux or being an audiophile, but I am new to using Linux as my digital source. I just thought that maybe someone could benefit from my recent experiences.

A little background:

Initially, my main interest in USB audio was to have an assortment of music playing through the house while I attended to thing like cooking and hobbies.

Instead of diving straight in with the purchase of a USB DAC, I thought I would test the waters by purchasing a HagUSB USB to S/PDIF converter to see how things would play out. I coupled the HagUSB to my my trusty Adcom GDA-700 DAC, which is usually fed with a Theta Digital Data Basic.

Initially I was not --in any shape or form-- expecting this combo to sound better than the original DAC and disc transport. But after one fortuitous listening session where I was actually paying attention to the music (in FLAC, fed by a Debian Thinkpad X40) when I was seated in the sweet spot, I could not believe the difference.

On albums with which I was intimately familiar with, voice and instruments were just more there. Decay on cymbals had more presence. I knew I was on to something.

I was using plain old XMMS on the laptop, but soon found out about (and fell in love with) Music Player Daemon, aka MPD. (http://www.musicpd.org). MPD is a music server that is controlled by a client. Since MDP is GPL, there are many different clients available. So, in order to perform a few experiments without spending as much cash as possible...

I installed Debian Linux on a Dell GX110 (P3 700Mhz, 256MB RAM; found in the trash in mint condition) desktop with a newly purchased Western Digital Green Power, i.e, low power consumption 750GB hard disk. MPD and proftp were installed via apt-get. Some discs were ripped with Grip, some with EAC (on an old hard disc I have with Windows XP) on the my main Linux desktop machine, with the FLAC files ftp'd to the Dell music server. USB output is via hardware output, thereby bypassing ALSA mixer. No software mixer is used. I'm using gmpc as the client; sometimes arranging play lists from the bedroom desktop, or using the Thinkpad wirelessly from the listening couch.

I am thoroughly enjoying music using this setup except for the fact that the Dell machine is a bit noisy. It was at this time that I found out about his thread, and was researching using a SBC (single board computer) from PC Engines (http://www.pcengines.ch/) as silent, flash based MPD server; accessing my FLAC files via NFS via my desktop PC.

I am investigating several options:

One is to use the ALIX alix3c2 SBC (http://www.pcengines.ch/alix3c2.htm) as my digital source controlled by mmpc (http://mmpc.garage.maemo.org/). With the ALIC board, I could install and run Debian on a 4 to 8 GB CF flash disk. The board could possibly be battery powered, which might afford some sonic benefits.

The other is to wait a while for the $199 Shuttle KPC (http://www.engadget.com/2008/01/08/s...barebones-kit/) and hope it's much quieter than my current setup.

Eventually I hope to have MPD controlled with a small web tablet like device. There are also several web based MPD clients (like Pitchfork) that would be perfect for devices like the Apple Ipod touch; fire up the Safari web browser and have access to all of your music on your Linux server.

I hope to report back soon....

[soundcheck]

Interesting NYC_paramedic. I'll have a look at the mpd.


One more comment to a USB connection in general:

First of all I do not think USB to SPDIF is the best way.
Empirical Audio offers a real nice USBtoI2S interface.
It's AFAIK a modded M-Audio Transit with a reclocker inside. You could even slave the M-Audio Transit to a clock master.
Under MS M-Audio supplies decent drivers. Under Linux it's a bit of a hazzle to get it work. Anyhow - it is possible.
That's IMO an interesting option to look at.
However we are at DIY-Audio. Modding should be actually our strength over here. After a while in the DIY domain
I realized that not any commercial product will suit my expectations.

A bit off topic (still touching upon some issues discussed earlier):

During the last weekend I introduced the ec-designs reclocker
to my DDDAC, hoping to find the holy grail.

OutOfTheBox I would rate it -- considering my very special environment -- "Something has to be heavily modded to get the full potential out of it".
The PCM2706 used just as a receiver is powered by noisy 5V PC-USB power. (I mean - I was pretty naively thinking the reclocker would be able manage all issues,
and the potential receiver issues wouldn't be a problem at all. Don't get me wrong here I don't blame ec-designs selling a module out of their overall solution. I am rather happy about this openess. As a standalone module you have to tweak the surrounding environment of course. I am still learning. )

After some hours of listening I can say, you hear more details and the sound gets this jitter-free fluidness and softness - this I expected. On the other hand you also hear a lot of power and/or power-noise related flaws, which makes the whole thing bold and fat sounding and out of focus.
I could not live with this situation, that's for sure. Don't get me wrong here- we are still talking real good quality audio in general!

What I've done, so far. I had the luck to get an Opticis Optical USB-extension
from Ebay. (Though I have to admit that I was very suspicious about these before.) It was sold by a UK meteorologist using it for galvanically isolating his equipment. He didn't have a clue what I wanted to use it for.
( Is there actually anybody interested to hear all this?? )
So I got it for 25pounds. Until now I didn't had time to try it because
it needed a better 5V supply. Since I was preparing these for
the reclocker I also made one for that optical extension.

Guess what. The heaven cleared after applying the cable to the
new setup. The above mentioned flaws "almost" disappeared. So, power quality is a mega-issue here-- that's for sure.
Perhaps a nice side-effect, with the reclocker I get rid of some extra jitter introduced by the optical transmission ( The anticipated extra jitter introduced by the Opticis was actually the reason for not trying it earlier)
For sure Doede did quite well by introducing a separated supply for the USB-receiver of his DDDAC. Still it is not galvanically isolated.
BTW Linux recognizes the Opticis extension without any problems.
I am just building TeddyRegs- the ones MaxLorenz was refering to.
Let see what they'll add to the sound quality.

The reclocker is supporting 44.1 only. Can I hear it?? I am not really sure.
Somehow I get the strange feeling that the stage got smaller again. The deep layering and separation disappeared. The things which heavily improved by introducing my 48kHz upsampling.
But this also might have something to do with the current PS situation.
One after another. First I get the PS right then I'll have a look at my beloved 48khz-upsampled data.

To summarize: If I get the power-supply issue solved and the 44.1 vs. 48khz comparison clarified, I might end up at a better setup then before.
Advise: If possible, you folks should try a galvanically separated approach - if you run USB DACS. Of course the Opticis would need a battery-powered supply.


Cheers

[UnixMan]

Originally posted by nyc_paramedic
I am investigating several options:

One is to use the ALIX alix3c2 SBC (http://www.pcengines.ch/alix3c2.htm) as my digital source controlled by mmpc (http://mmpc.garage.maemo.org/). With the

just a note: if you do/may have a system with a PCI BUS, I would rather AVOID the use of USB!

Instead, use some good "pro" audio card such as e.g. the E-Mu 1212m (or actually just a 1010 PCI digital interface) to provide a cleaner S/PDIF (or AES/EBU, or whatever...) digital stream to your DAC.

[soundcheck]

Paolo.

It's not that easy.
Even one of the best Digital Interface card such as the AES-16 from
Lynx is not really what some people would call perfect.

As long as you run asynchronous you need to reclock on the
receiving side. And here none of your mentioned interfaces will
be better then USB. There are DACs like the Benchmark DAC1, which are able to handle the USB traffic quite good actually and are able to beat other interfaces easily.

Don't forget the driver issue. Very often el cheapo soundcards come with poor drivers, which are messing around with the data stream.
It's not only the hardware. There are more factors.

The key is IMO to get the digital chain in sync. Meaning one master
clocking all slaves, such as a PCI interface card. Otherwise the DACs are slaved to the poor PC clock and are forced to make something great a out of it.

As long as we talk "Async or Isync" we can just try to get the best out of it.

Cheers

[nyc_paramedic]

Originally posted by soundcheck
[B]Interesting NYC_paramedic. I'll have a look at the mpd.


One more comment to a USB connection in general:

First of all I do not think USB to SPDIF is the best way...

I agree. But like I said, I was just experimenting, and the HagUSB let me do that for around 100 USD. The Dell was free, as was Debian Linux (but no less valuable).

I'm seriously considering the up coming new and improved Scott Nixon USB Tube DAC or the Version 2 of Wavelength's Brick. Once I settle on a dedicated USB DAC I will experiment, in earnest, with tweaking a RT kernel for the ALIX board, and run it on some type of battery.

I forgot to mention that MPD supports 100% buffer to RAM of songs before playing them. A nice feature if you ask me.



P.S. As for the rest of my system: B&W Matrix 804's, Pass Aleph 5 amp and Aleph L preamp, Adcom GDA-700. Alpha Core Goertz silver interconnects and some MIT speaker cable.

[UnixMan]

Originally posted by soundcheck
As long as you run asynchronous you need to reclock on the
receiving side.

asynchronous ?!?

AFAIK, all common audio interfaces (such as S/PDIF, etc) are (UNFORTUNATELY!) synchronous (isochronous).

BUT, just about ALL the "pro" and semi-pro cards can be "slaved" to an external clock! Thus you can get the clock from the DAC and feed it back to the card (of course, unless the DAC is somehow made to allow such things, it will need some mods).

Another option is doable even with much cheaper cards... just about any sound card which is (really) capable of running "full-duplex" S/PDIF I/O must be able to "slave" its S/PDIF output clock to its S/PDIF input (reconstructed) clock... so you can create a "dummy" S/PDIF stream locked to your DAC clock and feed it back to the card input. Again, you end up with a digital stream which is synchronous to your DAC clock ==> there is no need for reclocking.

Of course, again some hardware work will be likely needed on the DAC side to "isolate" the DAC from the S/PDIF receiver reconstructed clock and use your local one instead (as well as to generate the dummy S/PDIF stream, in this case).

BTW, IMHO either option should be MUCH better than any USB solution.

Originally posted by soundcheck
And here none of your mentioned interfaces will
be better then USB.

sorry, I doubt it... USB is simply terrible for audio... locking your audio clock to the USB one (which is not even at a "right" rate) IMHO is the worst thing you can do.

For what regards the drivers: we're talking about Linux, aren't we?

Then, the drivers are NOT written by the card manufacturer! They are (ALL) written by the ALSA developers and their quality does NOT depend on the card price.

The only real problem is rather whether the card is supported or not.

According to the ALSA matrix, the 1212 should be supported "out-of-the-box" in kernels >= 2.6.22 (which include alsa >= 1.0.14).

[nyc_paramedic]

Originally posted by UnixMan


just a note: if you do/may have a system with a PCI BUS, I would rather AVOID the use of USB!

Instead, use some good "pro" audio card such as e.g. the E-Mu 1212m (or actually just a 1010 PCI digital interface) to provide a cleaner S/PDIF (or AES/EBU, or whatever...) digital stream to your DAC.

I don't understand your reply. I thought USB was the way to go as far as better than S/PDIF audio quality. Especially since companies like Wavelength Audio have introduced Asychronous mode USB DAC's.

I plan on using a dedicated USB DAC as my critical digital source fed by a Linux MPD server.

Cheers.

[dwk123]

Originally posted by nyc_paramedic


I am investigating several options:

One is to use the ALIX alix3c2 SBC (http://www.pcengines.ch/alix3c2.htm) as my digital source controlled by mmpc (http://mmpc.garage.maemo.org/). With the ALIC board, I could install and run Debian on a 4 to 8 GB CF flash disk. The board could possibly be battery powered, which might afford some sonic benefits.

The other is to wait a while for the $199 Shuttle KPC (http://www.engadget.com/2008/01/08/s...barebones-kit/) and hope it's much quieter than my current setup.

I spent quite a while looking at ARM based SBC's, and while the geode based ones might be a bit more mainstream, with the advent of the Intel D201GLY2 I'm not sure the fringe offerings are worth the trouble. Running from flash, the Intel is well under 30W, which will give many hours of run time off a pico-psu and a mid-sized battery (say 33aH - I have some agm's in this size)

Eventually I hope to have MPD controlled with a small web tablet like device. There are also several web based MPD clients (like Pitchfork) that would be perfect for devices like the Apple Ipod touch; fire up the Safari web browser and have access to all of your music on your Linux server.

As I posted earlier in the thread, this is my setup. mpd controlled by phpMP via a Nokia 770. I think it's an amazing setup - being able to control directly from the listening seat is great.

Originally posted by nyc_paramedic


I don't understand your reply. I thought USB was the way to go as far as better than S/PDIF audio quality. Especially since companies like Wavelength Audio have introduced Asychronous mode USB DAC's.

Cheers.

Well, you'll get lots of different views on this. In my opinion, soundcheck's posts earlier in this thread illustrate why I find USB uninteresting - basically he reports that every little possible thing he did to his machine changed the sound. IMHO this reflects a rather poor interface.

SPDIF isn't great either unless you slave; if you do this, then it can be great, but aside from Empirical I'm not aware of anyone doing this commmercially.

I'm simply using an Emu 1820m and bypassing the whole transmission thing completely. (or rather, letting Emu handle it for me). By running balanced through the power amp, power supply noise becomes common-mode, which IMHO at the moment seems to be a big help in improving the analog quality of the output.

Originally posted by nyc_paramedic


I'm seriously considering the up coming new and improved Scott Nixon USB Tube DAC or the Version 2 of Wavelength's Brick.

Well, if you can spring for a Wavelength maybe some of the issues with USB will go away - from what I can tell Wavelength and Empirical are the only ones offering truly high-grade USB solutions; too rich for my blood, though.