The Audiotron is a music playback client that perfectly fits into your HiFi rack. All you need is a separat file server that stores the music (preferably as mp3) and a LAN to get in touch with this. Navigation through the music is done by the information of the mp3's ID3-Tags. Once you get familiar with this, you can free your living room of your CD piles. Depending on the balance of power in your partnership this might be an argument to get the 400 Euros for the Audiotron granted.

April 2005: Unfortunately, my Audiotron went dead. As these units are out of production and seem to be manufactured in poor quality I consider these units as history. RIP.

I purchased my Auditron in January 2002 from sparco.com. Sparco is one of the US retailers that do international shipment. After shipment and tax it was not a really cheap buy, but looking backwards I have to say that it was worth every dollar. When writing this I have my complete CD archive stored om my linux fileserver and I find it very convinient to listen to my music without the hassle of searching for CDs and inserting them into a player.

1. Audiotron? What do you talk about?

I am not going to explain what the Audiotron can do for you. There are a number of reviews on the web:

• Turtle Beach is producing the Audiotron as one of their mp3 devices: http://www.turtlebeach.com/
• Tom's Hardware likes it a lot: http://www4.tomshardware.com/network/01q4/011220/index.html
• ExtremTech compare the Audiotron with the RioReceiver (a similar device): http://www.extremetech.com/print_article/0,3428,a%253D15593,00.asp
• Prefect Pages Engineering are looking at the main hardware components that make up the Audiotron: http://www.gweep.net/~prefect/eng/audiotron/
• Actual firmware updates and a lot of discussion can be grabbed on the ezboard Audiotron forum: http://pub90.ezboard.com/bturtlebeach

2. Hardware Modification

Each of the modifications below will void your warranty and you do it at your own risk. Decide yourself, if you are willing to do the mod, but don't blame me, if you blow your Audiotron. I have done all the mods successfully with my Audiotron and it still works... may be I was just lucky ;-)

2.1 Power Supply

As the Audiotron is constrcuted for the US market only, its power supply does not support 220-230 voltages as they are mainly used around the world. Fortunately, the transformer inside the Audiotron has windings for 110 Volt and 220 Volt operation. There are two resources on the web that describe in a step by step manner how to modify the power supply to get the 220 Volt windings to be used instead of the 110 Volt branch. The instructions are very clear and you just need some basic experience in soldering. Have a look at http://www.bens-house.org.uk/LivingRoom/AudioTron/Convert.html or http://www.belgers.com/audiotron/.

Addition, Nov 2002: Since this summer VTB decided to sell a european 220 volt version by a retailer in denmark (http://www.internettuner.eu.com/). Therefore, you don't need to do the powersupply patch yourself until you like to do so.

2.2 Analog Output

The analog output of the Audiotron is bound to the RCA connectors at the back panel and the headphone connector at the front panel. The cabling of the headphone connector runs around the transformer and is therefore a source for distortions and noise. As most people do not intend to use the Audiotron's headphone connector (usually the amplifier drives the headphones) I did remove the cable in the Auditron that connects the 6 pin connector on the mainboard with the headphone connector at the front panel. To do this, just remove the cable and short circuit pin 1 with pin 2 and pin 5 with pin 6 of the connector on the mainboard. This is needed to bypass the analog signals directly to the RCA connectors at the back panel without tunneling them through the headphone connectors. You can expect to reduce the noise on the analog output by doing this.

2.3 Hard Reset From Front Panel

The Audiotron has a somehow weird power-on behaviour. It can be in one of four status.

• "no-power": The Audiotron is in "no power" mode when the power switch at the back is switched off.
• "powered on": The Audiotron is in "powered on" mode, when the power switch at the back is turned on. In this mode neither the remote control, nor the front panel (except stand-by button), nor the integrated web server is operational. The Audiotron is still asleep.
• "active": After being "powered on" the Audiotron must be made "active" by pressing the stand-by button (leftmost button on the front panel). Doing this the Audiotron starts its build-in web server and searches for music files over the net. Having done this, the remote and front panel buttons are fully operational.
• "stand by": Pressing the stand-by button while the Audiotron is in "active" mode makes it turning to "stand by". During "stand by" mode the webserver keeps running. The Audiotron can be turned to "active" mode again by pressing the stand-by button on its front panel or remote. A search for music is not performed when turning from "stand by" to "active"

The strange thing with this status model is, that you have to do a true power cycle to make the Audiotron to search for music from scratch. In order to make a rescan of the music files without pushing the power switch at the back panel of the Audiotron, I replaced the headphone connector of the front panel with a button, that hard resets the CPU by pulling the POR (power on reset) pin of the CPU to ground. POR is at pin 154 of the CPU, have a look at the CPU specs (Cirrus EP7312, page 28). You will find ground signal level easily on the mainboard. I used pin 10 of the 74LVX273 chip (that does the LED latching) for this purpose.

Pressing the reset button toggles the Audiotron to "powered on" mode. Pressing the stand-by button brings it to "active mode" including the desired new search for music.

2.4 Autostart After Power On or Hard Reset

Many users find the "powered on" mode useless and wish to bring the Audiotron directly to the "active" mode when doing a power cycle or pressing the above introduced reset button. One of the advantages would be, that the Audiotron will automatically search for new music after a power failure or manual reset. If you provoke a regular power failure during the night (by a timeswitch, for example) the Audiotron will automatically do a fresh music search during power up. As my music archive on the fileserver is being automatically updated from the internet from time to time, it is a great improvement to make the Audiotron to realize this updates without having me to press any buttons.

The easiest way to change the Audiotron's power-up behaviour would be to do a software change. Unfortunately, Turtle Beach tells me, that this part of the firmware cannot be updated. I guess it is part of the boot ROM that has to be passed before code from the flashable eeprom will be executed. So it might be out of reach for firmware flashing.

The automatic transition from "powered on" mode to "active" mode can be achieved by a circuit that...

• starts with the rising pulse at the POR pin of the CPU (this pulse is emitted by an rc element during power on or by pressing the reset button)...
• then waits for about 4 seconds...
• then gives a pulse with a length of about 1-2 seconds that somehow emulates a pressing of the stand-by button on the front panel.

How to build this circuitry?

Well, it is quite simple. Just have a look at the 74HC123 chip that operates as a dual monostabile multivibrator with a timing characteristic that is determined by an external R/C element. Pulse width (tw) computes as: tw [ns] = 0.45 x Rext [kOhm] x Cext [pF]. The pins of the 74HC123 should be connected as illustrated on the picture on the right.

It is important to bind all open input pins to a proper signal level (ground or Vcc). Otherwise you risk to receive noise on this pins that will disturb operation. As the 74HC123 is realized in CMOS it consumes very little power and the Audiotron power supply has no problem in driving it. The emulation of pressing the stand-by button is done by an optocoupler (CNY 74-2) as shown on the right.

Dimensioning of R, C, D:

• R1 = 220 Kilo Ohm 1/4 W
• R2 = 100 Kilo Ohm 1/4 W
• R3 = 47 Ohm 1/4 W
• C1 = 100 µF 16V
• C2 = 47 µF 16V
• D1, D2 any Shottky Diode

How to connect the circuitry?

To connect the inputs and outputs of the 74HC123 and CNY742 with the Audiotron you have to solder 5 wires. You definitely need some soldering experience to do this successfully. This is what I did:

• "VCC" is connected to pin 20 of the 74LVX273 on the Audiotron's mainboard.
• "GND" is connected to pin 10 of the 74LVX273.
• The "POR" input must be connected to pin 154 of the EP7312. As it's a highly compressed SMD-Package you need a very fine soldering tip to do this. Watch out not to connect the pins in the neighbourhood as well!
• "stand-by (-)" and "stand-by (+)" are connected in parallel to the stand-by button on the front panel. Just remove the printed board behind the front panel and have a look at the circuit tracks on it. You will easily find the circuit paths that belong to the stand-by button. Turn on the Audiotron, check polarity with a voltmeter, turn off the Audiotron again and connect "stand-by (-)" with the negative circuit path and "stand-by (+)" with the positve one. Having done this the optocoupler can virtually press the stand-by button :-)

Ok, it's not as simple as doing the other hardware modification, so you need some experience in soldering and a basic understanding in electronics. But it is no magic and I did the installation of the modification in about 30 minutes (most of the time searching for the best points where to place the connections to the Audiotron's circuit boards).

3. Software

The Audiotron's released (beta) firmware supports a so called "Table Of Contents" (TOC) feature since FW version 2.1.13 (have a look at the Audiotron API) that dramatically speeds up the process of searching for music during start up of the Audiotron. As my music archive resides on a linux server, I did some linux scripting that automatically builds an actual TOC file every night. To get the necessary information of each mp3 that should be represented in the TOC, I did a slight modification of the id3v2 package, that is available on SourceForge.

3.1 Modification of ID3V2

The Audiotron gets the information about artist, album, title, etc. from the id3 tags of the mp3 files. id3 tags come in two flavours. Version 1 has restricted length of information, while version 2 tags are unlimted in size. To avoid abreviations on long file names I decided to go with version 2 tags (id3v2). You can use tools like Tag&Rename to organize your id3 tags and convert v1 to v2 or vice versa. In the following I assume that you are working with id3v2 tags.

This is what you have to do in order to get the id3v2 package and my modifcations running on your linux system:

• Get id3v2 package (version 0.1.5) from "id3v2.sourceforge.net"
• id3lib (version 3.8.0 pre 2). If you are working on suse 7.3 this id3lib is already included in your linux distribution and you just have to install the package via YAST (don't forget to install the header files as well). If it is not there, have a look here.
• replace the following files of the original id3v2 distrubution by the modified versions:

• run "make" and "make install"
  

SONG
TIT2=Desire
TCON=Pop
TALB=Stella
TPE1=Yello
TRCK=01
DIR =Yello\Stella\
FILE=01 - Desire.mp3
END

3.2. Generation of TOC File

To build up a complete TOC file that contains all of your mp3 music just write a small script that uses "find" to run across your directories and collects all song descriptions by "id3v2 -P". Here is a sample shell script that does this for me:

#! /bin/sh
#mp3TOChome='/home/media'#
# use id3v2 with option -P to construct TOC for Audiotron
echo -n "Construct Audiotron TOC from ID3v2 Tags... "
cd $mp3TOChome
find Music -follow -type f -name '*.mp3' -exec id3v2 -P {} ';' > atrontc.vtc
echo "done."
#
# count number of songs
echo -n "Number of Songs:"
fgrep SONG $mp3TOChome/atrontc.vtc | wc -l