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 The Tunable Audio PC

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Join date : 2009-09-21

PostSubject: The Tunable Audio PC   Wed Mar 16, 2011 9:40 pm


I normally build my own personal computers at home and I'm a software engineer by profession, so I'm not completely new to this. However, this is my first attempt at building an audio PC. I'm going to walk through the entire build process so that anyone who wants to can build one for themselves.

The first thing to discuss is exactly what I am setting this computer up to do. Computers can play a lot of different roles in an audio system: network storage of audio data, playback device for a USB enabled DAC, playback device for an S/PDIF DAC, or standalone source with analog outputs. I am building a computer which will hold a digitized audio collection on its hard drives and export an S/PDIF signal by TosLink to an external DAC. My intention is that the computer will sit on the equipment rack and be tuned like any other component. It should have nothing connected to it except a power supply cord, an ethernet cable and the TosLink cable.

Why no monitor and keyboard? The monitor and keyboard are clunky attachments which are difficult to position near an equipment rack and a pain to use while listening. And I'd prefer not to worry about what having these devices attached to the computer will do to its tuning. The less parts involved, the better. The more elegant solution is to access the audio PC remotely from another computer on the network when you need to see its desktop. For normal music playback functions, a wireless remote like a smartphone or iPod will let you find and play your music without ever needing to see the computer.

Why the ethernet cable? For a computer with no monitor and keyboard attached, the network cable is necessary to allow remote access to the computer's desktop. It's also necessary for adding new music to the computer. Since the computer does not have a CD-ROM drive, any new albums have to be ripped to disk on another computer and then transferred over the network. The good news is that ordinary music playback is entirely internal to the computer; the network is uninvolved for anything except control signals. So tuning concerns for the network will hopefully be minimized.

Why TosLink? It electrically isolates the DAC from the computer. Digital chip operations create very grungy power, and keeping it separate from the DAC is a good idea. More than that, I have fried my Altmann DAC twice while connecting it to digital sources and I am really in love with the idea of never having that happen again. I'm aware that audiophile common wisdom is that coaxial digital connections sound better than TosLink, but Charles Altmann designed his DAC from the ground up to effectively handle the jitter from the TosLink interface, so I think this will work well. I'm also not sure that the common wisdom is correct on this.

After writing the above paragraphs, I am struck by the fact that the machine I'm building is almost completely customized to my own situation. It exports S/PDIF because that's what my DAC requires and it uses TosLink because my DAC is well set up for it. Someone with a USB DAC would at the very least have no need for the sound card I'm using. The build also assumes that you have a wired network and another computer. Another person could well prefer wireless, and that solution might arguably be superior from a tuning point of view as well. And my choice for using a smartphone as a remote is really driven by the fact that I have an iPhone and enjoy using the iPeng app to control my music collection. Also, my music collection is entirely 16/44.1- someone interested in hi res music files would probably end up with a significantly different software stack. The truth is, there are as many different ways to set up an audio PC as there are people. Rather than try to build an audio PC which is all things to all people, I'm going to post my own build here in the hopes that other tunees will find it a useful starting point.
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PostSubject: Hardware   Wed Mar 16, 2011 9:51 pm


Motherboard: The Jetway NC96FL-525 is based on the highly efficient Intel Atom processor, has no moving parts anywhere, is only 8”x8”, and takes an external 12V power supply. Tunable! cheers

I strongly suggest ordering it from Logic Supply. They have excellent customer support and reasonable prices. Make sure you get at least a gig of memory and a power supply with it, and pay them to test the board before they send it. For $15, you'd be crazy not to. Parts failures in new computer components are very common. N.B. It was their customer support that gave me the instructions on how to modify the BIOS in the post below.

Sound Card: ESI Juli@ This choice is the result of a recommendation by Charles Altmann. The board has a high quality TosLink output, dedicated audio clocks, and will handle high res audio files, as well as 16/44.1. It's also well supported on Windows, Mac OS, and Linux, so it's hard to go wrong.

Hard Drive: OCZ Vertex 2 60G SSD This was a difficult decision. I wanted to keep the computer free of vibration, so a solid state drive is clearly the way to go. The problem is that SSDs are expensive and don't come any larger than about 512G. And those will cost you upwards of $1000 each. My music collection occupies the better part of a terabyte, so we are talking a major expense.

On the other hand, a regular 1T hard drive goes for less than $100 these days. But they vibrate. My temporary compromise is to purchase a small SSD as a test and then get larger drives if things work out. I'd also like to pick up a regular hard drive and report on how it compares at some point. It could be that with proper tuning, an inexpensive hard drive might do just fine.

DVD-ROM: This is NOT part of the final computer, but is very useful while installing software. There are ways to install an operating system on a computer from a network connection, but this is a technically daunting task. Far easier to temporarily connect a DVD-ROM, and at $20 it's a cheap enough shortcut. Here's one.

From left to right: power supply, motherboard, Juli@ card, solid state drive.

The finished audio PC will probably weigh less than two pounds and should take up no more space on the rack than any other component. The size and weight of the computer should make it very tunable and the 12V power supply and low power requirements means it can be run from almost any 12V switching power supply, or even from a battery. The only downside that I can see is that the drive will need to be tuned separately from the motherboard.

In addition, this is a pretty inexpensive component. If you ignore the hard drive issue, the whole thing can be built for less than $400.


I have decided to add a monitor, mouse and keyboard to the equipment list. I probably won't be using these in my own system for the long run, but they will be very useful to Michael while he has the audio PC for evaluation and tuning. I think the below items are nice choices for any tunees who prefer direct input to their audio PC over remote control.

Monitor: I-Inc IK141ABB 14" Widescreen LED Monitor. This monitor has 1366x768 native resolution, and is as small and inexpensive as LED monitors come these days. The entire thing only weighs about 2 pounds, and the VGA cable that comes with it is as thin and light as any I've seen. I'm also really pleased with the picture quality and readability.

Keyboard and Mouse: Inland Utouch Multimedia Keyboard and Mouse Combo. This PS/2 mouse and keyboard are inexpensive and super lightweight. PS/2 connectivity is a very good thing with our motherboard since it has only 2 USB ports, so we can leave those open for other devices while the keyboard and mouse stay connected.

Next step: the build.

Last edited by Bill333 on Thu Mar 24, 2011 12:44 pm; edited 1 time in total
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PostSubject: The Build   Wed Mar 16, 2011 9:58 pm


The first thing to do is insert the RAM card into the slot on the motherboard. Next attach the monitor, the keyboard and the mouse. Plug in the power and... nothing happens.

Right out of the box, it will not be possible to boot the computer. This is because the board is set up to use a standard on/off button in a computer case. Since we're not using a case, we want to set up the computer to be turned on and off by connecting and disconnecting the power supply. Fortunately, everything we need to do this is in the BIOS. Here's how to do it:

1.Start the computer for the first time by shorting the power button pins with something metal. I used the tip of my mechanical pencil, but you could use a pen or a small screwdriver. The pins you want are identified on page 16 of the motherboard User's Manual under the heading 'Front Panel Header: JW-FP1'. Look at the drawing for the pins labeled PWRBTN and GND and find them on your motherboard. Just touch both of them at the same time with something metal and the computer will start up. Don't worry about touching the wrong pins in that group; there's really nothing there that can be harmed.
2.Immediately press DEL to go into the BIOS setup screen.
3.Select 'Power Management Setup'.
4.Go to 'ERP (EUP) Function' and set it to disabled.
5.Press ESC to go back to the main menu.
6.Go to 'Integrated Peripherals'.
7.Go to 'PWR Status After PWR Failure' and set it to always on.
8.Press F10 to save configuration changes and exit setup.

Power the computer down by unplugging it, and hook up the hard drive and the DVD-ROM. You will need the two SATA cables and the onboard power connector that comes with the motherboard.

Here's what the audio PC looks like on its messy desk test bed:

Next step: install an operating system.

Last edited by Bill333 on Thu Mar 24, 2011 12:11 pm; edited 1 time in total
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PostSubject: The Operating System   Wed Mar 16, 2011 10:50 pm


This is a choice fraught with peril.

Choose wrong and your hardware doesn't work and/or you can't find software that meets your needs. For instance, I first tried to install Windows 2000, but there are no Windows 2000 drivers for the video chipset on the Jetway board. There is a default driver which runs the screen at 640x480 and 16 colors, but that is not going to cut it for the long haul.

Now many people would just install the latest version of Windows and call it a day. But I am not many people. I am a person who hates handing money to Microsoft when there are perfectly good free operating systems around. Which brings us to Linux.

I asked the rep at Logic Supply about operating systems and he said that they install Ubuntu 10.04 on this board and that it supports the hardware just fine. That's great as far as it goes, but we also need support for the Juli@ card, and a software music player which will not only work with the card but can be controlled with an iPhone app. After a little research, the Juli@ card should be no problem and I was able to locate at least a couple different options for music players. So Ubuntu Linux it is.

Another nice thing about Linux as a choice for the audio PC is that the motherboard we're using has a dual core CPU and recent versions of Linux handle multiple processors very well. What this means is that our audio application can loaf along with a CPU to itself while the OS takes care of its own business on the other CPU.

Ubuntu 10.04 is the Long Term Support version of Ubuntu, which means that Canonical will be supporting it for at least 3 years. Go to the Ubuntu download page and follow the directions for downloading the iso file and then burning it to a CD. Put the CD in the DVD-ROM while the computer is booting up and follow the installation instructions. Make sure you have the computer plugged into your network and you'll be all ready to go with internet access as soon as the install finishes. If you're following this build with the recommended hardware, you should be looking at a beautiful and fast new Linux system in no time.

The default installation of Ubuntu 10.04 goes into screensaver mode and logs the user out after the computer has been idle for 5 minutes. Going to screensaver is probably not something we want our audio PC doing, and being forced to log back in at the keyboard is definitely not something we want happening. So go to System>Preferences>Screensaver and uncheck the boxes labeled 'Activate screensaver when computer is idle' and 'Lock screen when screensaver is active'. Click 'Close' and we're done.

If other tunees feel more comfortable with Windows, that's certainly an option. You will just need to do your own research on the software. And if anything goes wrong with my Linux build, I might be joining you. But so far, things are looking just fine with Ubuntu.

Next step: Install the sound card.

Last edited by Bill333 on Wed Apr 06, 2011 6:19 pm; edited 1 time in total
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PostSubject: Re: The Tunable Audio PC   Thu Mar 24, 2011 1:00 pm


Simply shut the computer down, insert the Juli@ card into the PCI slot, and boot it back up. Go to System > Preferences > Sound and set the output volume slider to 100%. Click on the Hardware tab and you should see two devices: the first is labeled 'Internal Audio', and the second is labeled 'VT1720/24...'. Click on 'VT1720/24...' and under Settings for the selected device, select 'Digital Stereo Duplex (IEC958)'. Click on the Output tab and select the radio button for the 'VT1720/24'. Close the dialog box and you're done.

You may need to reboot the computer, but at this point you should be able to hear system sounds through your DAC when you start the computer up, or play sound effects from inside the Sound Preferences dialog.

Last edited by Bill333 on Wed Apr 06, 2011 6:32 pm; edited 1 time in total
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PostSubject: Re: The Tunable Audio PC   Thu Mar 24, 2011 2:45 pm


I expect putting together the software stack to be by far the most challenging part of the audio PC build, if only because there are so many different choices and what is useful to one person in one situation may not be to another. But the first thing to do with every learning curve is just to get started.

Job number one for an audio PC is to pass bit perfect audio to the sound card. The trouble is that there are all manner of programs and operating system routines that will adjust volume, reshape, rebalance and generally wreak havoc with our digital signal if they get the chance. We need to make sure that these functions are disabled and that the playback program we use is set up to pass music files through at the same resolution and bit depth at which they were stored.

Fortunately, there are some helpful guides available on the internet for setting up bit-perfect audio on Ubuntu. With thanks to Rizlaw at Head-fi.org:

In all cases make sure that in Linux: you set your hardware for digital output, your volume control is set to 100%, and that any other sound features such as “replay gain”, mixers, system sounds, equalizers, are all disabled. You do not want any manipulation of the digital audio stream inside the computer.


Step 1: Obtain a copy of "gmusicbrowser" ver 1.1.6, music player. For Debian based distros, it can be downloaded from: https://launchpad.net/ubuntu/+source/gmusicbrowser or http://shimmerproject.org/projects/gmusicbrowser/ or http://gmusicbrowser.org/download.html

In Ubuntu it can also be installed as a PPA (personal package archive) by opening Administration > Software Sources and adding "ppa:shimmerproject/ppa" (omit quotation marks). https://launchpad.net/~shimmerproject/+archive/ppa
Then open Synpatic Package Manager and search for "gmusicbrowser", select it, and click apply to download and install it.

Step 2: After installing gmusicbrowser, start the program and enter "Settings" menu. Go to the "Audio" tab and for output device select "ALSA". On the same "Audio" page, select "advanced options" and for "alsa device" enter "hw:0,1" (omit quotes).

IMPORTANT NOTE: you need to determine what your Linux OS considers the digital output for your sound card. It may not be "hw:0,1" in your case. To do this, open a terminal window and enter the command: "aplay -l" (no quotes). You will get a list, look for the digital output for your sound card. For the Xonar STX the output reads:

card:0 STX (Xonar STX), device 1: Digital (Digital)
subdivces: 0/1

Step 3: adjust all other settings in gmusicbrowser and play a 24/96 track. You should be getting true bit perfect output. In my case, the W4S DAC-2 has a display to confirm this fact.


You can try the same thing with "Quodlibet" another very good Linux music player.

QUODLIBET music player – digital output via Asus Xonar STX card:

Open Quodlibet and click on: MUSIC menu > Preferences > Player

In the Player tab's “Output pipeline” box enter: alsasink device=hw:0,1

Click the “Apply” button and you're done



Additionally, you can try MPD:

MPD (music player daemon):

MPD is a very popular music player daemon for Linux. One installed, you can use a number of different client gui's to control playing your music (i.e. GMPC and ARIO are 2 popular clients). All the software can be found in the Ubuntu Repositories. Install MPD + the MPD extra plugin and at least one client (GMPC).

To get MPD to send bit perfect audio to an external DAC, you need to make a few modifications to the default “mpd.conf” file located in the /etc directory.

Open a terminal and enter: gksu gedit /etc/mpd.conf

This will open the mpd.conf file for editiing.

1. At the beginning of the mpd.conf file, for the “music_directory” path enter the path to your music files. For most users this will be /home/your_user_name/music. NOTE: mpd seems to prefer that you keep you music files in top level folders, so if you make a lot of subfolders, mpd will have a tough time trying to index your music. In other words, it's best to keep all the songs for each album in one folder like:

/music/carly_simon-hello_big_man/ *.flac



2. Toward the bottom of the mpd.conf file, you will find the Audio Output section. We are only concerned with ALSA output. The code below shows the “modified mpd.conf” file, carefully compare it to the default mpd.conf file in your text editor to see the differences.

# An example of an ALSA output:
audio_output {
name"My ALSA Device"
device"hw:0,1"# optional
#format"44100:16:2"# optional
#mixer_device"default"# optional
#mixer_control"PCM"# optional
#mixer_index"0"# optional

3. You must ADD four extra “#” marks as shown above. This disables those features and allows bit perfect digital output.
4. In addition, make the change to the line beginning with "device" to add your correct “hw:x,x” device. You can find your digital device's output setting using the command “aplay -l” in a terminal window ( lower case “L” and omit quotations marks in command).


And finally from www.webup8.org, http://www.webupd8.org/2010/03/how-to-switch-to-alsa-or-oss-instead-of.html

you can try: gconf-editor. In a terminal type: sudo gconf-editor

Navigate to /system/gstreamer/0.10/default and change the "audiosink" and "musicaudiosink" to "alsasink" or "osssink", depending on what you want to use. I for one used OSS ("osssink" - notice there are 3 s) because it simply works, even though it's deprecated.

If you want to do this via command line, all you have to do is paste this in a terminal:
gconftool-2 --type string --set /system/gstreamer/0.10/default/audiosink "osssink"
gconftool-2 --type string --set /system/gstreamer/0.10/default/musicaudiosink "osssink"

The above 2 commands set GStreamer to use OSS for audio and video players. To use ALSA instead of OSS, simply replace "osssink" with "alsasink" in both commands above.

If you want to use ALSA or OSS for Audio/Video Conferencing too, also run the following command (remember, the app must be using GStreamer):
gconftool-2 --type string --set /system/gstreamer/0.10/default/chataudiosink "osssink"

To use ALSA, simply replace "osssink" with "alsasink" in the command above.

Then restart your music player or video player (Rhythmbox, Totem, etc.).
To reset these values to default, run this in a terminal:

gconftool-2 --type string --set /system/gstreamer/0.10/default/audiosink "autoaudiosink"
gconftool-2 --type string --set /system/gstreamer/0.10/default/musicaudiosink "autoaudiosink"

I have setup gmusicbrowser for temporary use, but will probably need to choose something else when I need remote control support. 'hw:1,1' is the correct device number for this motherboard and sound card setup, and has been tested successfully with an external DAC.

Last edited by Bill333 on Wed Apr 06, 2011 6:21 pm; edited 1 time in total
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Michael Green

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PostSubject: Re: The Tunable Audio PC   Thu Mar 24, 2011 10:33 pm

The Tuning Part

Not to interrupt the flow of what Bill333 is working on but to briefly say that the other end of this project is in motion. I say "in motion" because I'm doing research on all of the electronic parts being used to provide any circuitry support.

The fun for me is unlocking the door to movement (vibration) and how it is effecting the sound. It's my belief that the effects of the vibration going on in the parts (of which there are still many although a minimalistic approach) are as big as the assigned function of the parts themselves.

I might give some basic notes to keep the thoughts fresh as we get into this stage.

for example: what is a capacitor?

"Take two electrical conductors (things that let electricity flow through them) and separate them with an insulator (a material that doesn't let electricity flow very well) and you make a capacitor: something that can store electrical energy. Adding electrical energy to a capacitor is called charging; releasing the energy from a capacitor is known as discharging.

A capacitor is a bit like a battery, but it has a different job to do. A battery uses chemicals to store electrical energy and release it very slowly through a circuit—sometimes (in the case of a quartz watch) it can take several years. A capacitor generally releases its energy much more rapidly—often in seconds or less. If you're taking a flash photograph, for example, you need your camera to produce a huge burst of light in a fraction of a second. A capacitor attached to the flash gun charges up for a few seconds using energy from your camera's batteries. (It takes time to charge a capacitor and that's why you typically have to wait a little while to take a flash photo.) Once the capacitor is fully charged, it can release all that energy in an instant through the xenon flash bulb. Zap!

Capacitors come in all shapes and sizes, but they usually have the same basic components. There are the two conductors (known as plates, largely for historic reasons) and there's the insulator in between them (called the dielectric). The two plates inside a capacitor are wired to two electrical connections on the outside called terminals, which are like thin metal legs you can hook into an electric circuit."

michael green
PH 702 762 3245
Email mgtune@yahoo.com
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Michael Green

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PostSubject: Re: The Tunable Audio PC   Sat Mar 26, 2011 11:13 am

Hi Guys

I'm getting space ready for the next, very exciting chapter for the tune. Bill333 has been great in getting me up to speed on the ways of the computer world and I feel I'm now starting to get my head around the flow of things to come. It's helpful to see the step by step recipe that Bill333 has laid out. Seeing and feeling the stages is half the battle for me. Parts and pieces begin to become a linked chain that can be followed from beginning to the ear.

Digital Meets Analog

Where does digital stop and analog begin will be something that I hope we can make clear for those who follow in this adventure's footsteps.

michael green
PH 702 762 3245
Email mgtune@yahoo.com
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PostSubject: Re: The Tunable Audio PC   Fri Sep 07, 2012 4:09 am

Hi Michael,
I'm going to try to get my computer source closer to the system by using a Mac mini. Would this be my best option? (I like Macs) I'm still looking into it, but I may be able to use the Mac's hard drive for my collection instead of the NAS I'm using. Or not.
Any further ideas on tuning for computer audio???
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PostSubject: Using Computers as Front End Digital Sources and More   Tue Jun 16, 2015 11:17 am


I find computers as excellent digital front-ends in the audio chain and whole-heartedly recommend them!

Over the years, there seems to be two main camps; both of which I am proficient and support.

Camp 1:
"Keep it Simple, Silly"... Use a Mac Mini or other Mac and just plug the thing in and it works. Add a bluetooth keyboard and mouse and a DAC and you're in business. Assuming you have a Home Theater or other means of amplification setup with an HD Television; which most households do by now.

Camp 2:
Linux and custom builds. This is by far more difficult for the average listener, but if anyone has an overlapping interest in computers, this can be very rewarding and fun. I fully support the poster who built their own linux machine and provided detailed instructions.

I will just leave it at this level to see if anyone in 2015 is interested in discussing this topic here on Tuneland.


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PostSubject: Re: The Tunable Audio PC   Tue Sep 15, 2015 8:17 am

Hi Ron,

I think you're referring to me as the poster who built their own Linux machine and provided instructions. I have to say that project wasn't really successful. The computer/Altmann DAC combination never performed as well as the Magnavox and I left the motherboard running on the test bench without proper support for too long and it fried itself.

I haven't used a computer based source since then. If I were to try it over again, I'd probably get a Mac Mini with an SD card reader and try some different combinations of Mac and Windows based systems. I think a lot of progress has been made in figuring out how to improve the sound by cleaning up and isolating the ground planes in the computer.
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