Precision Tools for Audio Professionals

About the ARX Audibox USB series

We have designed the USB series to take advantage of the Plug and Play protocols built into the Windows and Mac operating systems.
The USB-DI, the USB DI-VC and the USB I/O are completely Plug and Play, which means that you just connect one of them to a USB port on the computer and 5 to 10 seconds later it will be ready for use, without having to load any drivers.

To be able to do this, the USB-DI uses the generic USB audio driver built in to the operating system. And like everything in life, there are rules built in to this generic driver which have to be followed

Let's go over the rules for audio via USB on computers, in order to get the best quality sound::

1. The USB port that you use on the host computer must be used for the USB-DI only.
2. Don't plug USB-DI into a hub unless you want additional noise from other devices plugged into the same hub.
   However - If you are using a laptop with only 1 USB connector and have to use a hub, then check all the ports on the hub to find the quietest one, and be very careful when using other USB devices connected to the hub at the same time.
3. You can only use ONE installed audio device at a time. If you plug in another, the computer will assume you want to use it and stop using the previous one. If you then unplug the second one, the first will be available again, although you may have to re-select it from the list of Audio Devices. Go to Control Panel/Sounds and Audio Devices/ and click the list of Sound Playback and Sound Recording Devices.
4. Depending on how your computer is set up, the USB-DI will automatically install itself as the default audio device as soon as it is plugged in. If not, you'll have to choose it from the above-mentioned list.

Q: "My USB DI works fine during soundcheck, but 'goes to sleep' just before showtime, and needs to be disconnected and then re-connected before it will work. What's wrong?"

A: Luckily this is a power management setting problem, and not the USB-DI's. Here's how to fix it in Windows:

1. Open the Control Panel
2. Click on System
3. Click on the Hardware tab, then Click on Device Manager
4. Click the + on Universal Serial Bus Controllers
5. Scroll down to USB Root Hub
6. Click on this, then click on the Power Management tab.
7. You'll see a box with a tick in it, marked Allow the computer to turn off this device to save power. Click on the box to remove the tick then click on the OK button at the bottom of the window
8. Repeat this process from stage 6 above for all the USB Root Hubs listed.

This should solve the 'USB DI goes to sleep' problem". This is a government mandated power saving move, to prevent excess energy use, which probably works well for data, but not for music!

Q: "The output of my USB DI is not loud enough or"
Q: "The output of my USB DI is noisy"

A: These two problems have the same cause – excessive gain at the mixer needs to be applied to deliver the level required, drastically lowering the signal to noise ratio.

As luck would have it, though, there is a simple solution. 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 the gain following the USB-DI is increased

We recommend increasing this volume setting to 100%, on both PCs and Macs. Here's how to fix it:

1. Once the USB-DI is connected and has been recognised, Click on Control Panel
2. Click on Sounds and Audio Devices
3. Click on USB Audio Device
4. Click on the Volume tab, and move the slider to the right, to 100%

This will give you the optimum signal to noise ratio and allow you to reduce the gain on the mixer.

NOTE: This still needs to be done even if you are using the USB DI-VC model. The volume control on this model 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

Q: "The Input to my USB I/O is too hot and is overloading the computer/hard disk recorder"

A: For this we will have to dig into the operating system again, and this time reduce the Input to the USB I/O.

1. Once the USB-I/O is connected and has been recognised, Click on Control Panel
2. Click on Sounds and Audio Device. Or, if you have the speaker icon on your taskbar, Right Click on it and select Adjust Audio Properties
3. Click on USB Audio Device
4. Click on the AUDIO tab
5. Click on Sound Recording, then the Volume slider
6. Set to Minimum (This is not off but low) and then adjust upwards as necessary to get a suitable level

Q: "After I connect the USB DI I get a hissing and/or clicking noise when I move my USB mouse"

A: USB is a very popular Plug and Play protocol for lots of Windows devices. It's quite likely that you will already have various USB devices in use on your computer.
For fastest and quietest audio operation you must plug the USB-DI / USB DI-VC/ USB I/O into its own USB port. Experiment on your computer to find the quietest USB port, and keep it only for the USB-DI - don't have anything else on the same bus.
We don't recommend the use of a hub that you have connected to the computer, unless you only have one port on say, an older laptop. Even then your audio may not be as good as it could be. Try to avoid using the other USB devices on the computer whenever you are using the USB DI

Q: "My onboard soundcard stopped working when I connected my USB DI"

A: With USB Plug and Play, you can only use ONE audio device on a computer at a time. If you plug in another, the previous one will stop. If you then unplug the second one, the first will be available, although you may have to re-select it from the list of Audio Devices. Go to Control Panel/Sounds and Audio Devices/ and click the list of Sound Playback and Sound Recording Devices.

Q: "My laptop audio is noisy when I run it from the power supply, but clean when I run it from the battery"

A: Although 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.
Some are very good, and quiet, but many 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 a fully charged 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! 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.
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.

Q: "I get a buzzing sound when I sit my USB I/O next to my mixer's power supply"

A: The complete ARX Audibox USB series contain multiple transformers, double shielded for ultra low noise. However, they are still transformers, and as such they are always looking for something electrical to transform! Do not sit any of your USB devices next to, or on top of a power supply, power amplifier, or similar AC connected device. These can spray out Radio Frequency (RF) interference, digital 'zipper' noise, hum and buzz inducing noise in large amounts that may force their way into the transformers inside the USB DIs. Keep them as far away as necessary to avoid this happening.