A U S T R A L I A N ||| W E B S I T E

Precision Tools for Audio Professionals

About the ARX Audibox USB series

• The ARX Audibox USB series of devices are true Plug-and-Play Digital/Analog audio interfaces, using the popular Universal Serial Bus connector found on computers - a digital version of the common Direct Injection (DI), or Direct box.
• They are self contained, stand alone stereo units designed to interface stereo digital audio with professional balanced low impedance inputs.
• They convert digital audio signals from your computer into analog ones that are happy to travel down a long line into a mixing console at the other end. In the case of the USB I-O it will also go the other way and convert analog signals to digital as well, making it a truly universal In/Out device.
• Transformer isolated dual XLR connectors supply Balanced audio output from a USB connection.
• Full Transformer Balanced output isolation eliminates earth loops / ground hum and other interaction noise and distortion.
• A front panel status LED indicates that the unit is connected and operating.

Power
No external power is required - all power required is supplied by the USB bus in the computer.

Drivers
No drivers are required for operation under Windows XP, Vista or Windows 7, and Macs running OS X or later. The USB devices are instantly recognised as generic USB audio devices, requiring no special driver program installation.

USB Cable
We recommend you use either the USB cable supplied, or one no more than 4 metres (~12 feet) long.

In these Application and Installation Notes we will go over the differences in each of the units, what they can and can't do, and any special things you may need to note when using with the various operating systems on today's computers.

Also please look at USB audio Q and A - it's full of important and essential information on how USB audio works, what it can and can't do, and how to make it do what you want

USB DI
Very straightforward, intuitive Plug and Play device. Nothing to do except plug it in. Installs itself as a USB audio device, and as the default audio device while it is connected.

Ground Lift switch ensures signal isolation and quiet operation. See Important Note # 1 below

All transformer balanced analog audio output on male XLR connectors

Hand made in Australia

USB DI VC
Very straightforward, intuitive Plug and Play device. Electronically identical to the USB DI, with the addition of a Volume Control on the Analog outputs.

Note that this is an attenuator and can reduce level only. There is no gain on the output control (it won't go to 11!) so you will need to check the Important Note # 1 below.
Installs itself as a USB audio device, and as the default audio device while it is connected.

Ground Lift switch ensures signal isolation and quiet operation. All transformer balanced analog audio output on male XLR connectors

Hand made in Australia

USB I/O
Very straightforward, intuitive Plug and Play device. The USB I/O will convert analog audio to digital, and digital to analog, via the USB connector. Analog inputs and outputs are all transformer balanced and isolated.
You will need to check Important Note # 1 below to set the digital output level.
The input level will be controlled by your recording software and your operating system, so you will need to have this installed BEFORE using the USB I/O

Installs itself as a USB audio device, and as the default audio device while it is connected.

Ground Lift switch ensures signal isolation and quiet operation.

Hand made in Australia

Rear Panel for the USB-DI and the USB-DI VC, showing Left and Right Transformer Balanced and Isolated male XLR connectors

Rear Panel for the USB I-O, showing Left and Right Transformer Balanced and Isolated Input and Output XLR connectors

Plug and Play
If you are running Windows XP, Vista or Windows 7, Mac running OS X or later, as soon as you plug the USB-DI into a spare USB port on the computer it will be recognised as a USB Audio Device, and will be ready straight away.

Windows 98 Compatibility?
Windows 98 SE is supported and can be installed as a USB composite device.
You will need the 98SE CD Rom for driver installation.

With Win 98SE, as soon as you plug the USB-DI into a spare USB port on the computer it will be recognised as a USB Composite Device, and the Add New Hardware Wizard screen will pop up. Click NEXT on the first 2 screens, put in the 98SE CD Rom, then select CD Rom drive on the search screen and click NEXT. Click NEXT on the following pop up screen, then FINISH on the final screen.

It will then install the USB Device drivers, and repeat the install process for a USB Audio Device.

Click Here to see the full Win 98SE Installation process

Operating instructions USB-DI and USB-DI VC

Input Connections
Connect the USB connector to the USB-DI and to the USB port on the computer. On Windows XP, Vista or Windows 7, Macs running OS X or later it will be available immediately and the LED on the front of the USB-DI will light up. On 98SE follow the previous instructions. You will need the 98 SE install CD Rom.

Adjust the Audio Level as described in the Important #1 note below.

Output Connections
Connect a balanced microphone lead from each 3 pin XLR connector on the USB-DI to a pair of input channels on the mixing console. Set the Input Gains on the channels, and Pan the channels Left or Right as required.

To check that the USB-DI is set up correctly, open your audio software, ensure that USB Audio Device is selected as the default audio device. Then either open a music file and play, or put an audio CD into your CD drive and play it.

And yes, that's really all there is to it. But we strongly suggest you read the following important things ensure that your ARX Audibox USB device delivers 100% quality, 100% of the time.

Firstly, make sure you have some audio recording/playback software installed on your computer.

Connect the USB connector on the USB-I/O to the USB port on the computer. On XP and later it will be available immediately and the LED on the front of the USB-I/O will light up.

Input Connections
Connect a balanced microphone lead from the Left and Right outputs of a mixer to the Left and Right 3 pin XLR Input on the USB-I/O. You cannot plug microphones directly into the USB I/O - you need a preamp or mixer. The inputs on the USB I/O are Line level, not Mic level

Output Connections
Connect a balanced microphone lead from the Left and Right 3 pin XLR output connectors on the USB-I/O to a pair of input channels on the mixing console. Set the Input Gains on the channels, and Pan the channels Left or Right as required. Outputs of the USB I/O are Line level

To RECORD with the USB-I/O, open your audio software, ensure that ARX Systems USB is selected as the default audio device, and follow the record instructions as you would normally.

When the USB-I/O has audio passing through it, either In or Out, the LED on the front panel will start flashing.

To PLAY, open your audio software, ensure that ARX Systems USB is selected as the default audio device, open a music file and play.

BUT – before you do, there are a few very important things you should know before starting out with the USB-I/O

IMPORTANT # 1

The Windows default volume setting for USB Audio Devices is 50% of maximum. For our purposes this will be too low, inducing noise and hum as excessive gain may need to be applied to deliver the level required.

We recommend increasing this volume setting to 100%, on both PCs and Macs.

No matter which operating system you are using, once the USB-DI is installed, go to Control Panel, then Sounds and Audio Devices, then USB Audio Device, then the Volume tab, and move the slider to the right.

This will give you the optimum signal to noise ratio.
<<< See panel at left

NOTE: This still needs to be done even if you are using the USB DI-VC model. The volume control only affects the analog outputs, and you'll need to increase the digital volume first.

NOTE 2: This will need to be done each time you plug the USB-unit in after removing it.

IMPORTANT # 2

Laptops and Power
If you are using a laptop/notebook computer with the Audibox USB-DI / USB DI-VC / USB I/O, we strongly recommend that where possible you run the computer from its battery - fully charged, of course!
We have done extensive research on grounding and signal isolating techniques on our USB series of products, and have incorporated all of it into their design.
While it may be more convenient to run a laptop from its external power supply, the sad truth is that not all external power supplies are created equal; in fact many of them are just not up to the standard required for any kind of audio.

Many often come with the surprise addition of a pink noise, digital noise and hum generator built in, a feature which unfortunately cannot be disabled!

Price and brand also have very little bearing on the quality of the laptop power supply! It's a very good idea to carefully check your laptop and power supply combination prior to any kind of audio use, and if in doubt, stay with the battery.

Another alternative is one of the aftermarket generic power supplies, as sold by many computer shops. However, try before you buy is the name of the game!

Desktop Computers and Power
The Grounding layout of Desktop PCs, Macs and their Power Supplies is also sadly not one of life's great constants, as they all feature widely varying grounding arrangements. To compensate for this, and to assure you of the lowest possible system signal to noise ratio, we've fitted the whole USB Series with a Ground lift switch that allows connection or isolation between your Computer's ground, and the grounding pin 1 on the units XLR connectors. Simply select the setting, in or out, that removes any audible hum when using your Computer USB DI or I/O combination.

Stay Alive!
And remember, never ever remove, snap or cut off the Safety Earth pin on any Power Lead associated with your Computer, its Power Supply or any of your Audio Equipment, as this could expose you and those around you to a potentially fatal risk of electric shock.
If after switching your USB unit's ground lift switch in and out and comparing hum levels your system is still noisy, consult a Technician as your problem lies elsewhere.

 
USB DI Schematic Diagram

USB DI VC Schematic Diagram

Input Connector USB type B port

Output Impedance 300 Ohms Transformer Balanced

Output Level Maximum nominal output level 0dB; user variable from infinity to 0dB on VC model

Output Noise
USB - System dependent
ISO transformer - Enviroment sensitive

Frequency Response 20 - 20 KHz ± 0.5 dB

Power Operating current via USB Port 80mA

Output Connectors
2 x Male XLR, wired Pin 2 + Hot, Pin 3 – Cold. Pin 1 Floating / not connected

Construction
All-steel powdercoated chassis, fibreglass PCB, epoxy printing, slip-resistant rubber feet

System Requirements

• Windows PC running Windows XP, Vista or Windows 7, Mac running OS X or later
• USB port
• 98SE will need the Win 98SE CD Rom to install driver. However, in reality if you're serious about music you'll already be using a later operating system

 
USB I/O Schematic Diagram

Connector USB type B port

Codec 16 bit, 48 Khz

Input Impedance 10 KOhms Transformer Balanced

Output Impedance 300 Ohms Transformer Balanced

Maximum Input Level Nominal 0 dB - Line level

Maximum Output Level Nominal 0 dB - Line level

Input/Output Noise
USB - System dependent
ISO transformer - Enviroment sensitive

Frequency Response 20 - 20 KHz ± 0.5 dB

Power Operating current via USB Port 80mA

Input Connectors
2 x Female XLR, wired Pin 2 + Hot, Pin 3 – Cold. Pin 1 via ground Lift switch

Output Connectors
2 x Male XLR, wired Pin 2 + Hot, Pin 3 – Cold. Pin 1 via ground Lift switch

Construction
All-steel powdercoated chassis, fibreglass PCB, epoxy printing,
slip-resistant rubber feet

System Requirements

• Windows PC running Windows XP, Vista or Windows 7, Mac running OS X or later
• USB port
• Audio software installed
• 98SE will need the Win 98SE CD Rom to install driver. However, in reality if you're serious about music you'll already be using a later operating system