[Magnum]

I just pointed out thas it wasnt just slightly faster. Maybe it matters, maybe not. I prefer my CPU idling at 3% at 24/192 rather than 15-20%. In my experience faster CPUs mean better sound.
I know "it doesnt matter" regarding the actual power to decode 24/384khz. If I did not know that, I surely would not be running Linux on an ATV. If it "didnt matter, why dont you run full blown Ubuntu on the Alix (OK so you cant reallu without a VGA card, but thats beside the point). The LX800 should still be overkill if the OS is just idling and you only use MPD. Why don´t you try and report back?

Let me get this out:
I like the Apple TV. It already good to go when you buy one.
1. It looks good.
2. Its cheap.
3. Built in PSU means only a small power cable is needed.
4. Its still small with a HDD inside. Perfect to take away on vacation or something.
5. It works for me. The Alixx works for you.
6. We should move on.

Did you not say that you tried out the RT Kernel earlier? Did you not append the parameter "threadirqs" to the Kernel line in the file /boot/grub/menu.lst ? Well that is all you need to do. The difference should be clear.

[ctviggen]

My rule is that if it has a fan, it's not silent.  Ever.  I can hear my Dell Zino from across the room with TV on (and the Dell is behind a TV).  My Antec P180 case sounds like a jet engine to me.  As soon as the fan gets dust on it, it's loud. 

Here's my latest computer:

http://www.hd-plex.com/H3.SODD.html

Completely FANLESS.  Yes, FANLESS.  No fan whatsoever. Let me repeat that: NO FAN.  With a solid state drive, no moving parts except for a bluray/DVD player (and they sell another version without the bluray/DVD player). 

[nyc_paramedic]

I just pointed out thas it wasnt just slightly faster. Maybe it matters, maybe not.

This.

I prefer my CPU idling at 3% at 24/192 rather than 15-20%.

Plus this.

 

In my experience faster CPUs mean better sound.

Plus this.

I know "it doesnt matter" regarding the actual power to decode 24/384khz.

Equals: You're talking a lot, but you're not saying anything.

If I did not know that, I surely would not be running Linux on an ATV.

But, you said:

In my experience faster CPUs mean better sound.

If it "didnt matter, why dont you run full blown Ubuntu on the Alix (OK so you cant reallu without a VGA card, but thats beside the point). The LX800 should still be overkill if the OS is just idling and you only use MPD. Why don´t you try and report back?

Again, you're talking a lot, but you're not  saying anything.

I was talking about Alix hardware with Voyage MPD (minimal Debian, running in RAM, no X,  a minimum of services, no HDD and MPD as the star daemon running). It doesn't matter because we don't need to prioritize MPD threads on a system that has all of its RAM and CPU dedicated to MPD by default. Where's the latency problem? Where are the buffer under runs? Where is the high disk and PCI I/O? We deal with high latency by not introducing it in the first place.

And no, a standard kernel from kernel.org does not come pre-configured with RT enabled. Even with 3.0.0, RT patches have to be applied by the user. There is a good reason why RT kernels are not the default: They can cause more problems than they're are worth. They're designed for very specific applications and care has to be taken with configuration.

From Linux Torvalds: http://yarchive.net/comp/linux/rtlinux.html

Also, some people will he happy to know that soft-RT ends up getting
continually improved, and many people might be able to find that just the
regular preemptible kernel gives good enough latency at least if you can
limit the workload on the machine (which, on embedded devices tends to be
something you take for granted anyway).

Also:

My point is that from a technical standpoint, I think giving user land
higher priorities than the kernel is _wrong_.

It gets you into all the priority inversion stuff, where you suddently
must not do simple system calls because the regular kernel locks are no
longer safe to use. That's a HUGE design mistake, and a classic one. Yes,
others have done it that way. A billion flies _can_ be wrong - I'd rather
eat lamb chops than shit.

And:

“Controlling a laser with Linux is crazy, but everyone in this room is crazy in his own way. So if you want to use Linux to control an industrial welding laser, I have no problem with your using PREEMPT_RT.” -- Linus Torvalds


Let me be blunt and tell you what I think: You're advocating the use of an Linux RT kernel on a minimalist hardware and software platform that can easily handle playing back high resolution files with negligible latency. I think you found this website, http://kubotayo.web.fc2.com/voyagempd.html#patch, applied the changes step by step, and convinced your self that the sound before was "lifeless" and after was "and BAM the sound was now very clearly better than the Mac."

I think you don't understand the utility of what an RT kernel is really for. Do you have a CPU that has to control multiple control surfaces in a flight critical system in addition to computing a whole host of calculations? Or more applicably, an Ubuntu Studio desktop that is recording multiple (high disk IO, etc.) 24/192 streams that have to sync within milliseconds, then RT is for you! Otherwise you're turning a simple mouse trap into a Rube Goldberg machine to catch just one mouse.

On top of that, there is no "better" that you claim. I know plenty of audiophiles who buy gear because they like their music "warm", i.e., with added distortion. Some audiophiles have colored (again, warm) speakers and subconsciously use other pieces of gear as tone controls. And yet even more audiophiles refuse to invest in room treatments...

Did you not say that you tried out the RT Kernel earlier? Did you not append the parameter "threadirqs" to the Kernel line in the file /boot/grub/menu.lst ? Well that is all you need to do. The difference should be clear.

I did. A while back. No difference. You're comparing apples (Apple TV) and oranges (Alix) without even owning a basket of oranges.

Even though I like to tinker, I realized the stock configuration sounds wonderful. It sounded wonderful from day one, circa 2008. I notice some slight differences between battery, linear supply and the stock switching wall wart. And contrary to what some people think, the switching wall wart is actually very good. I trust my ears, not some made up internal bias.

[Magnum]

Jesus, please stop with the take-no-prisoners multiquoting and Faust-like psycho analyzing. You know nothing about me or my background, and this isn't an exercise about semantics. We are not discussing my CV but our experiences with the RT Kernel.

I installed default Voyage MPD first. At the time I was unaware of all the tweaking, RT and other stuff. I wanted it to sound better than my Mac right of out the box. It did not, even though the Mac is runing a full blown OS with GUI and numerous background processes. So I had to google how to get good sound in Linux. There are a few pages on the net and they are mostly the same. I was at Kubota site too, but I'm not using the same settings. I  have tried changing the settings back to default and the sound does change. But the biggest change is probably just changing the Kernel. That is why I want people to try just this one thing. If there is no difference, then change back. No need to tweak further to see if there is any miniscule difference.

It is also easy to compare the Mac and the ATV. It is just a matter of unplugging the USB cable and put it into the other. It takes 5 seconds, and I've done it enough times that I am certain that there is a big difference. I don't have 2 QB9s to do a DBT, so this is what you get. What's more I'll even set up a second ATV with default settings to directly compare apples to apples. (And no I was never comparing apples to oranges. Once again, I was talking about RT Kernel in general only, and I did say the whole time that I didn't own an Alix)
Since I have yet to install Voyage MPD 0.8, I'll probably get round to installing it on both ATVs one of these days. 


I know that "better" isn't always neccesarily "better", but we are not talking about 2 different poweramps with different sonic signatures. Better in my case means the same sound but higher subjective sonic quality in all the key areas. I do not wan't to talk about my set up (let's stick to the case), but I can assure you that it is resolving enough. I think even you would approve. After all, we do own the same USB Dac.

I do know what a RT system used for. ABS brakes anyone?  I'm not advocating it because it sounds cool or anything. My point is that things that might not make apparent sense, still makes a difference when we are dealing with audio. Practical experience should weigh heavier than theory. Ask any audio equipment designer.

I am still not sure if the mainline 3.0.0 Kernel has RT functions. It thought I read it in this thread a few pages earlier but I'm not certain of that.

[toddbagwell]

Magnum and NYC, this is a great thread- evenn though i'm not entirely sure what half of the posts mean as i don't run Linux. 

It is a great reference thread, and i'd hate to have to lock it if you guys start getting into personal attacks. Please, take a breath, and return to posting tomorrow or whenever you feel like discussing things without the jabs and barbs.

Todd

[Magnum]

I have now configured 2 ATV running Voyage MPD 0.8.
One is completely stock Voyage MPD. Just edited mpd.conf to reflect my preferred sound device with auto switching of sample rate.
The other is my tweaked one with a realtime kernel. I had to build my own kernel for Voyage 0.8 for it to be 100% compatible with Voyage MPD 0.8.
To compare them I just need to replug the USB cable from my Ayre QB9 DAC into either one of the ATVs. No rebooting or other things neccesary.

To cut the story short: The ATV with the realtime kernel is so much better in all areas that its not even funny. It is much much more open and finegrained in the sound. And that settles it for me.

If interested I could post my realtime kernel if others want to try it out.

[TomS]

I have now configured 2 ATV running Voyage MPD 0.8.
One is completely stock Voyage MPD. Just edited mpd.conf to reflect my preferred sound device with auto switching of sample rate.
The other is my tweaked one with a realtime kernel. I had to build my own kernel for Voyage 0.8 for it to be 100% compatible with Voyage MPD 0.8.
To compare them I just need to replug the USB cable from my Ayre QB9 DAC into either one of the ATVs. No rebooting or other things neccesary.

To cut the story short: The ATV with the realtime kernel is so much better in all areas that its not even funny. It is much much more open and finegrained in the sound. And that settles it for me.

If interested I could post my realtime kernel if others want to try it out.

It would be helpful to know how to do it on the Alix step by step. I just have one board now, but it's pretty quick to just swap the CF card with the other image and reboot it.

[nyc_paramedic]

I have now configured 2 ATV running Voyage MPD 0.8.
One is completely stock Voyage MPD. Just edited mpd.conf to reflect my preferred sound device with auto switching of sample rate.
The other is my tweaked one with a realtime kernel. I had to build my own kernel for Voyage 0.8 for it to be 100% compatible with Voyage MPD 0.8.
To compare them I just need to replug the USB cable from my Ayre QB9 DAC into either one of the ATVs. No rebooting or other things neccesary.

To cut the story short: The ATV with the realtime kernel is so much better in all areas that its not even funny. It is much much more open and finegrained in the sound. And that settles it for me.

If interested I could post my realtime kernel if others want to try it out.

Sure. Post it. What about the mpd daemon patched with RT?

[hometheaterdoc]

Magnum,

I'm very curious to know how you did the setup for your Apple TVs.  Did you follow any online guides or was this all common knowledge for yourself?  Would you be willing to start another thread and give a blow by blow install guide?  I just picked up a couple 1st gen Apple TVs to do just as you are doing. 

I'm also ordering a couple Alix boards and will follow all the help from this thread and other online guides to set them up as well... 

I'd like to compare each of these setups against my windows based audio PCs, plus the network bridge of the PS Audio PerfectWave DAC and various transports I have here.  Whatever sounds the best will win.  I think it'll be great fun and a nice experiment.  I've got several nice USB capable DACs here: 

1) the aforementioned PS Audio PWD (which is about to have a new digital board released for it that will include asynch USB in addition to it's network bridge capability

2) Antelope Audio Zodiac Gold with the Voltikus power supply

3) Abbingdon Music Research (AMR) DP-777 with the dual DAC chip setup...

Ease of setup, the functionality of the clients, the perk of near or completely silent operation in the room, etc. are all important.. but I'm mostly concerned with which one is the best sounding.  I already have a 10 inch android tablet, an apple ipod touch (bought solely to use as a remote for PS Audio PWD), and I already have my music collection stored on a different server in another room.  This thread has inspired me to jump back in to the Unix/Linux world (I did Unix administration and email administration on a unix box years and years and years ago and did play around a bit with a couple dist. of Linux about 8 years ago... never went that deep with it and I honestly forget 99% of it now I've been in the windoze world so long)  and see how these units stack up against the windows based machines I've been using all these years.  I've also got several local audio buddies with mac minis tricked out... so it will be a great experiment to have them bring their machines over as well and compare......  I'll have to do a get together and let others listen and compare and weigh in on which they think is the best...

now to do more reading on Linux and the various wiki links and setup links and blog posts....  I'll likely be back to this thread to ask dumb questions and have you point out the most obvious things that I'm doing wrong   Thanks in advance for your assistance...

[Magnum]

Magnum,

I'm very curious to know how you did the setup for your Apple TVs.  Did you follow any online guides or was this all common knowledge for yourself?  Would you be willing to start another thread and give a blow by blow install guide?  I just picked up a couple 1st gen Apple TVs to do just as you are doing. 

There is no online guide so I had to figure it out myself. Took me a little while to figure it out but it wasnt that bad. I could not figure out how to boot the Voyage MPD live disk from a USB stick, so in the end I managed to get it work by using a USB DVD-ROM. Basically you need a USB hub, a USB memory stick, a USB DVD-Rom and a copy of the Voyage MPD live cd. I´ll come back to making a thread about the installation.

[hometheaterdoc]

Magnum,

Thanks for the reply.  I would really appreciate it if you would do a write up.  Thanks also for the heads up on the USB rom drive requirement.  I can likely cobble something together with a USB hard drive enclosure and long cables to simulate the same thing with a standard ROM drive... or I could just order one since I need to order CF cards anyways

4 Alix boards and enclosures just shipped.  I figure if this is half as good as it seems, I'll have a few buddies wanting me to build them one.  Shipping was the same price for 1 as it was for 4... so why not, right?   I'll also need several of these units as I have multiple rooms full of systems... that reminds me... one more thing to add to the list...  now I need to find out which clients will allow me to easily switch and control multiple units from the same Toshiba android tablet...

I've already got a couple of my techie buddies looking at a super performing, but inexpensive power supply instead of a wall wart... one of them wants to wait to get the boards here to see what might need to be swapped on the board or how far to go if the board changes are not possible...  it should be interesting...  great thread... I finally couldn't take it any longer and needed to jump in and see what this was all about...

[praedet]

Have the guy making a new PS compare to running of DC as well...

[nyc_paramedic]

MPD 0.17 real time build:

http://www.multiupload.com/UU3CZ9TIQV

I did not build this myself, I have edited the script a bit though.
Just download the zip file ann unzip it somewhere on your MPD server.

then cd to the unzipped folder and type "./mpdinstall.sh"
Only use the script ONCE and never again.
reboot.
You should now be running Linux RT with RT enabled MPD.

There a a few more things you could tweak, but this is basically it.

It's common courtesy to link to the website from where you got that software. Not only as a courtesy to the person who actually did the compiling, but also as a courtesy to the users here who need to make a decision on whether they want to install untrusted software on their machines. I would NOT install the software you linked to and would advise users here not to as well.

Also, installing the RT kernel and RT enable MPD and adding threadirqs to grub is NOT "basically" it. There are other parameters that need to be configured.

But I asked you *numerous* times to detail the settings you applied so that I and others can make as much a similar comparison as possible. You have been vague, to say the least, and evasive.

Please, start your own thread so that you may misinform users there. Thanks.

[Magnum]

I really don´t want to either argue or fight on the internet, so I´ll just ignore you completely after this post.

I think the users here can make their own choice. Just have a look in the script it does not do anything remotely dangerous.
I did compile the kernel myself, what´s to say that I didn´t put in some kind of virus in the kernel?
I could compile my own MPD from the GIT repository too, I just couldn´t be bothered as the end result would be the same. Anyways the pre-compiled MPD is from http://http://blog.naver.com/manishin

Yep, that *is* basically it. What more do you want? Using the chrt command to change priorities?
I only use that to change the USB irq, I was going to come to that. I don´t have any other secret ingredient apart from deselecting some of the services, which is non-critical, and to my ears pretty much unneeded.

[hometheaterdoc]

Magnum,

Can you please PM, email (sales at hometheaterdoc dot com) or otherwise post in another thread about how you did the setup of the Apple TVs?  I've got a couple here to play with and would like to try your implementation.  I've got the USB based DVD-ROM drive ready to go...

My Alix boards are also hopefully going to be here today (cleared through customs at JFK 4 days ago)...  I'll likely be back with questions as I try to set them up.... 

lots of computer changes this weekend.  Moving my office to other parts of the place and trying to figure out how to keep everything networked properly...  should be fun

[PET-240]

G'day All,

Just read this thread, still getting my head around Linux etc, I have on order an Alix 2d2, a WaveIO and a Buffalo III, so this setup is where I'm looking, has there been any advances since November last year regarding setup, RT kernel etc?

Thanks for all the info here,

D.

[vorko]

How would the Alixx board compare to a plug computer like this one (http://www.globalscaletechnologies.com/t-dreamplugdetails.aspx) ?

[stagnant7]

Hi,

I have set up a mpd music server using an Alix 2d2 with the help of this forum and it has been going very well. However I cannot seek/skip though songs when they are playing. I have activated the mixer_type "software" in mpd.conf, and I can now use the volume control, but when I want to click on the progress bar in gmpc to advance a song that is playing, the music stops and doesn't seem to resume.

The Alix is hard wired to the router whereas my server is in a different room and connected to network via wifi.  Would this have any impact on it not working?

Some help on this would be most welcome.

Thanks

[Bill Wayson]

First, much thanks to nyc_paramedic (Nick) and everyone else who created and contributed to this invaluable thread.  It has guided my project to modernize my home sound system.  Thank you all.  If you ever are near Ventura, CA, I extend an invitation to attend one of our low-key monthly Linux meetings to talk about your Linux Audio Server experience.

I am at the point where I can replace my laptop MPD server with an Alix setup, and I'd like some advice from anyone.  I do not have a DAC nor do I have the cash to buy a really nice one.  So, which is the better route:  buy an Alix 3D3 and use the headphone output, or buy the 3D2 (or other model) along with an inexpensive DAC?  If you advise the latter, is there an inexpensive DAC you'd recommend?  I am not an audiophile and not so concerned with absolutely great sound.  I look forward to your opinions and thank you in advance for them.

Bill Wayson

[clog]

Bill I don't know what money you wish to spend, but I use the Alix 3D2 with the ODAC (http://nwavguy.blogspot.com). A very good DAC that costs about 100-150 $ depending on the
case you want. It's a smooth combination with the ALIX. No hiccups, no glitches, no drivers.