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The Firewire standard
works in two different versions. The first version
(known as the backplane version) uses a
backplane physical layer and supports transfer
burst rates of 12.5, 25, and 50 Megabits per second
(Mbits/sec). The second version (known as the cable
version) supports data burst rates of up to
100, 200, and 400 Mbits/sec. This makes Firewire
one of the fastest peripheral standards ever created.
Firewire peripherals are also "hot-swappable" — you
can plug or unplug any number of devices while
the devices and computer are "running".
(This is vastly different from SCSI devices, for
example, all of which must be powered down before
they can be connected and disconnected.) Another
great feature of Firewire is that is supports
up to 63 devices with a maximum cable length of
4.5 meters (14.8 ft.). If longer cable lengths
are desired, you can run up to 16 devices with
a maximum length of 72 meters (236 ft.). When
multiple Firewire devices are used, each device
automatically determines its own address, which
makes Firewire very easy to use.
Another interesting fact: all
Firewire hard drives are actually IDE hard drives
with an interface controller. This controller transfers
the data between the Firewire bus and the IDE hard
drive.
Recently there has been an influx
of Firewire hard drives to the market. A number
of these hard drives have made their way into professional
and home studios. Firewire drives provide a large
amount of storage at a fairly low cost, which makes
them great candidates for DAW’s (Digital Audio
Workstations.) Studio owners that are looking at
Firewire drives always have one question: How reliable
are these drives and can I use them to record and
playback audio? The answer to this question is that
most of the "over-the-counter" Firewire
hard drives cannot be effectively used with DAW’s.
Here’s why
Almost all Firewire hard drives
function in half duplex mode, which means they cannot
read and write at the same time. This is problematic
when trying to record and playback audio from a
Firewire Hard Drive. Another problem is that when
used with audio applications, a specific driver
is needed to enable full duplex mode. This driver
is also required to allow the drive the ability
to "stream" data continuously to the hard
drive. Most users of Firewire hard drives experience
a large amount of dropouts and glitches when recording
to and from their drives. This makes the drive only
useful for storage.
There are a number of "over
the counter" Firewire drives where the cases
and power supplies are not shielded. Non-shielded
drives can often add additional AC line noise, RFI
and EMI into the Firewire chain making your clean
digital audio tracks well, not so clean. Non-shielded
drives if located near another USB or Firewire audio
device can also introduce noise into the audio device.
So how do you know what options
to look for when purchasing a Firewire hard drive?
One of the first requirements
you need to look at is what kind of data throughput
you are going to need. The best Firewire hard drives,
that are made specifically for audio, are able to
stream up to a maximum of around 30 MB per second.
While this is fine for most recording applications,
some people require better throughput. Most "over
the counter" hard drives only stream up to
a maximum of around 20 MB/sec. If you are curious
on how much throughput you might need, please CLICK
HERE. (pdf file 80K)
Another requirement that you
need to look at is the Chipset that the controller
is using. The only chipset that has been recommend
for use with audio applications is the Oxford 911.
The 911 chipset is one of the most reliable. Digidesign
has endorsed the Oxford 911 and it is the only chipset
used by Glyph Technologies in all of their Firewire
hard drives. The 911 is compatible with all operating
systems, chipsets, and audio interfaces, yet there
have been cases where Firewire drives with the 911
chipset, still have problems streaming audio data.
If this happens on a Mac, this usually means you
need a driver for your hard drive. Glyph makes a
driver, but this driver is only available when you
purchase one of their Firewire products.
If you are running a PC and
do not have a Firewire port on your Motherboard,
you can add a PCI Firewire card. Most Firewire PCI
cards are very inexpensive, but we recommend only
running those approved for audio applications. Otherwise
you might get a PCI card that is not able to stream
data correctly. One of the cards we recommend is
the Glyph
Firewire PCI card.
In conclusion, a Firewire
Hard Drive can be a great addition to anyone’s
studio and can be invaluable purchase to people
recording on laptops. Unfortunately most drives
are not made for audio recording. If you are worried
about compatibility and would like to skip a potential
number of headaches you should probably take a look
at some of Firewire drives that Glyph makes as they
are already optimized for digital audio.
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