Computer Audio Playback
As use of the personal computer (PC) has become more prevalent, it is no surprise that
their use for music servers has become as popular as it is now. A music collection can
easily consist of thousands of songs which can then be organized and played back all
without having to change a single record, tape, or disc. With the introduction of the Ayre
USB digital to analog (D/A) converter, now these collections can be played back with
unprecedented fidelity and realism.
Connected via a USB port and using the StreamlengthTM
asynchronous USB transfer mode software
licensed from Wavelength Audio, an Ayre USB D/A converter generates a fixed-frequency
master audio clock for jitter-free playback of your music. Now the D/A converter is in
control and provides the critical master audio clock; the computer simply stores the music
files. Ayre USB D/A converters also utilize techniques to provide total electrical
isolation between your computer and music system.
For playback of files up to 96 kHz this is all done using the standard device drivers
supplied with all recent operating systems, allowing simple installation and operation with
most computers. (Going beyond 96 kHz has special requirements as noted below.)
Important Reminder - Back Up Your Music Files!
No matter what your choice of computer, operating system, and music playing software,
please remember one important fact—all hard drives will eventually develop problems and you
may lose precious data. Be sure to back up your music files! You will likely end up with
hundreds of hours and/or thousands of dollars invested in these files. Taking a few minutes
to back them up can save a lot of heartache down the road.
Class 1 or Class 2
The vast majority of currently available music files are at sample rates of 96 kHz or
below. As computer audio continues to mature there will be an increasing number of files
available at 176.4 kHz and 192 kHz. Standard computer audio with files up to 96 kHz
typically operate under what is called "Class 1 Audio" which is a subset of USB 1.1. The
transmission rate for Class 1 Audio is 12 MHz. To go beyond 96 kHz requires the use of a
protocol called "Class 2 Audio", which operates in conjunction with USB 2.0. Class 2 Audio
uses a transmission rate of 480 MHz, or forty times faster than standard USB computer
audio. This means that there is forty times less margin for timing error, and that
everything in the signal path must be essentially perfect to achieve good results.
The easiest way to determine whether Class 1 or Class 2 audio is right for you is to simply
look at the sample rate of your music collection. As it is important to play your audio at
the same sample rate as it was recorded, there is no reason to meet the more strict
requirements of Class 2 audio if none of your music is over a 96 kHz sample rate. If you do
intend to play files up to 192 kHz, please refer to the Going Beyond 96 kHz
section below to ensure you've met all
necessary requirements before attempting to play back your collection in this mode.
Before you attempt to work with files beyond 96 kHz, please go through the normal setup
instructions for your Operating System. Make sure that everything is working properly and
you are familiar with your system and its software. Only then should you attempt to work
with files beyond 96 kHz.
Computer Hardware Requirements
Your computer must have at least one available USB port. You will want plenty of hard
drive space for storing your music files. As a rough estimate, two full-length albums
will require 1 GB of hard drive space if the files are uncompressed. Therefore a
library of 1,000 CD's would require roughly 500 GB of disk space. Lossless compression
(e.g., FLAC or ALAC) can save around 40% on the storage space required, so that same
500 GB could store over 1400 CD's. Lossy compression (e.g., MP3, AAC) is not
recommended as it permanently reduces the sound quality of the music file.
Operating System Requirements
Windows XP Service Pack 2, or newer. (The driver model used in earlier versions of
Windows will not give reliable results with asynchronous USB transfers.)
Apple OS X 10.4.x, or newer.
Linux (If you know enough about computers to use Linux, you'll know enough how to
figure out what is required.)
USB Cable Requirements
Perhaps the one weakness of USB is that the maximum cable length is somewhat limited,
typically 3 meters (~10') to 5 meters (~16'). We have found that one of the most common
problems encountered when setting up a USB-based music system is the cable itself.
Regardless of any claims from the cable manufacturer, we have found that performance
can degrade when exceeding 3 meters. Ayre cannot guarantee the operation or performance
of any system utilizing a USB cable longer than 3 meters.
In the case when it is not possible to locate the USB D/A converter within 3 meters of
the computer, Ayre has found that the Icron USB extender works well. It is claimed to work up to
100 meters. We have tested it up to 100' and have no reason to doubt their claim.
It also operates reliably at speeds up to 192 kHz, even with the asynchronous
operation used in the Ayre D/A converters which require concurrent signal
transmission in both directions. It is not inexpensive, at around $325 in the US,
but a low-cost ($50) USB extender we tested did not function at all with an Ayre
USB D/A converter. There may be other similar products that work well, but we have
not tested them and cannot verify their performance.
No matter what operating system (OS) your computer uses—Apple, Windows, or Linux—you'll
need to set up your computer for performing several different tasks:
1. Transferring music to your computer's hard drive, either by converting the files from
your CD collection, commonly called “ripping”, or by purchasing files that are available
for downloaded via the internet.
2. Labeling the files you have transferred with the names of the song, artist, album, et
cetera, commonly called “tagging”. (Downloaded files will normally already have the tags
3. Using a music player program to organize your music collection and play it back.
4. Optionally recording music selections back onto CDs for playback in your car or other
places, commonly called “burning”.
5. Optionally transferring part of your music collection to a portable music player,
commonly called “syncing”.
A few programs can perform all of these functions, for example iTunes (Apple and Windows),
J.River Media Center (Windows), and Foobar (Windows). Some users will prefer to use other
software packages or even a combination of other specialized programs to perform these
functions, but for most users we recommend using one of these all-in-one software packages.
Apple or Windows?
If you are setting up a music server for the first time, possibly the simplest route is to
purchase a new Mac Mini or other Apple computer. It will come pre-loaded with a variety of
software (including iTunes) and works especially well with other Apple products such as the
iPod. While it is very easy to set up one of these systems, music player software choices
other than iTunes may be limited.
Apple Setup Instructions
There are many valid reasons for using a Windows computer as your music server. You may
already be using a Windows computer, or you may be more familiar with the Windows operating
system. The music player software applications available for Windows may offer more
flexibility or customization than is available with iTunes. However, there are typically
more choices and steps when setting up a Windows computer as a music server.
Windows Setup Instructions
If you are still unsure of which way to go, read the music player setup instructions for
each OS on these pages. You will find additional information that will help guide your
Going Beyond 96 kHz
Before you attempt to work with files beyond 96 kHz, please go through the normal setup
instructions with your player set in Class 1 mode. Make sure that everything is working
properly and you are familiar with your system and its software. Only then should you
attempt to work with files beyond 96 kHz.
Links to Other Useful Computer Audio Websites
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D/A Converter Requirements
All Ayre DX-5 universal audio engines and all QB-9 USB D/A converters manufactured
after the summer of 2010 have the capability to handle music files up to 192 kHz and 24
bits of resolution. Older QB-9's may be updated for a nominal fee, either by the
factory or by the distributor in your country. In either case, simply take the unit to
your local dealer and they will make the necessary arrangements.
To determine if your QB-9 is capable of accepting music files beyond 96 kHz, look at
the serial number on the rear panel. The letter in the serial number determines when
the unit was made. If the serial number is 18Fxxxx or beyond (e.g., 18Gxxxx), then the
unit was manufactured at the factory with the high-speed USB input PCB required to go
beyond 96 kHz. If the unit was updated, then the letter "F" (or beyond) will be
appended to the original serial number (e.g., 18CxxxxF). If you have any questions,
contact your local dealer or distributor.
On the rear panel of both the Ayre DX-5 and QB-9 is a bank of DIP switches. The default
that works well for most users is that all switches will be in the "up" position. The
switch labeled "Rsrv A" (up) and "Rsrv B" (down) selects the operating class of the
unit. Rsrv A puts the unit into Class 1 Audio mode, and will work without any special
drivers as outlined on the main setup pages. Use a toothpick or ball-point pen to flip
the switch down to Rsrv B and now the unit will operate in Class 2 Audio mode.
Changing the D/A converter from Class 1 to Class 2 is actually one of the last steps
you will want to take during the system setup. There are several more steps to perform
with a Mac computer, and many more steps to perform with a Windows machine. You may
encounter problems if you change the DIP switch too soon. Don't worry though - you can
always just flip the switch up to return to Class 1 Audio and get sound with music
files up to and including 96 kHz.
The USB processor chip only "reads" the position of the "Rsrv A"/"Rsrv B" rear-panel
switch upon start-up. As the processor is powered by the USB connection, it is
critically important to disconnect and then reconnect the USB cable after changing the
position of the rear-panel switch. This will "re-boot" the USB processor and it will
then "read" the new position of the switch.
USB Cable Requirements
The USB cable connecting your computer and D/A converter is one of the most critical
components of a Class 2 Audio system. Most of the time that we experience reports of
problems, it is simply the cable that is at fault.
The USB 2.0 specification lists a maximum cable length of 5 meters (~15 feet). This is
marginal with the best of cables, and many "audiophile grade" cables will run into
problems even with far shorter lengths. There have been many credible reports of
improved sound quality with some cables, but these have almost all been in systems
using Class 1 Audio, with a maximum data rate of 12 MHz. When the data rate is boosted
by a factor of 40x to 480 MHz, there are very few "audiophile" cable companies that
have the tools and experience to ensure good results.
Regardless of the brand you are best off to use the shortest practicable cable, usually
between 1 meter (3 feet) and 2 meters (6 feet) in length. If you need to go longer, be
sure to test the actual make and model and length to ensure that it will work properly.
Ayre includes an inexpensive USB cable with each unit that provides a good starting
point, as it is known to work. The bottom line is to get the system working properly
first. Then you can worry about fine-tuning for the best possible sound later.
USB Controller Requirements
The second most common cause of problems with Class 2 Audio is the USB controller. This
is an electronic circuit ("chip") inside your computer, driving the actual USB
connector that is familiar to you. When USB 2.0 was first introduced, the controller
chips were simply not finished products. We have had several instances of laptop
computers (circa 2005-6) that nominally had USB 2.0 ports but would not work properly.
Adding a newer external USB controller via the PC-Card port solved the problem.
Regardless of how new your computer (and USB controller) is, there is one cardinal rule
— for Class 2 Audio the Ayre USB D/A converter cannot share a USB controller with any
other devices. Again, we will cover this in more detail in the individual pages for
Apple and Windows machines.