M-Audio OmniStudio USB [10/45] Theory of operation

A recording console performs two functions. It routes the signal you are about to record, providing the ability to pre-amplify and shape that

signal before it gets to the recording device. At the same time, it handles all playback, allowing you to mix, add an effect, and monitor your

recorded signal as well as your “virtual” MIDI keyboard tracks.

The OmniStudio USB is designed to perform these tasks. The OmniStudio USB, in conjunction with your PC or Macintosh computer and

compatible audio software, adds the functionality of a recording console in a desktop unit. The OmniStudio USB is modeled after what is

known as a “split console” design, where the recording and monitoring sections function independently.

Two high quality M-Audio Mic/Instrument preamps are routed to the OmniStudio USB’s analog inputs 1 and 2. The level you record is controlled by

the OmniStudio USB preamp’s independent gain controls in conjunction with the 20dB pad switch. An insert jack added to the record path

allows you to process the signal with outboard gear, should you choose to. Line Inputs 3 & 4 offer you selectable input level of +4dB or -10dB,

and give you a total of 4 direct analog inputs to your computer.

The audio from your computer connects to the OmniStudio’s internal mixer, with individual FX Send Level controls to create a mono FX Send.

This internal mixer then blends the audio from your computer with the Direct Monitor levels, the four Stereo Aux Inputs, and the audio from

the FX Returns. The OmniStudio USB’s rear panel Stereo Aux Inputs can also be routed directly to the OmniStudio USB’s inputs to the computer,

making it extremely convenient when you want to record your “virtual” tracks. The OmniStudio USB’s four Direct Outs take the audio from your

computer and bypass the OmniStudio’s internal mixer. These can simultaneously be used as independent balanced/unbalanced direct

outputs for additional effects sends, alternate mix outputs or feeds to a secondary mixer.

USB Operability

The USB port provides a high-speed connection to your computer. Devices can be “hot-plugged” into the USB port with no need to

power down the computer. Additionally, there’s no need to open the computer, no tools are required, nor is it necessary to configure

the device other than installing the drivers and plugging it in to the USB port.The OmniStudio USB utilizes the convenience of your

computer’s USB port to bring high quality, high resolution audio to your desktop or laptop computer. The PC requires no IRQ other than

the one that is already dedicated to the USB controller when it is enabled.

It is important to note that while multiple devices can, in theory, be connected to the USB port (with the addition of a USB hub), audio

over USB requires significant bandwidth. We therefore recommend that you plug the OmniStudio USB directly into your computer’s USB

port, and not into a USB hub shared with other devices. Of course, if you are using a USB keyboard and mouse, you may have those

plugged into your computer’s other USB port (two are usually supplied on PC and Mac).

Note, however, that in most computers these two USB ports ultimately share a single USB bus, and all devices connected to either port

will create bandwidth demands to some degree. For optimal audio performance, we strongly recommend refraining from using other

bandwidth-intensive USB devices (e.g., printers, scanners, modems, etc.) while recording. In fact, in many cases it’s best to disconnect

these devices entirely while recording – some device drivers are written to“poll” (send a signal to) the CPU every millisecond, even

when not in use, and this can lead to drop-outs or noise in your audio.

Audio Protocols

Your OmniStudio USB is a 24-bit /96kHz capable device. This means you can record at any sampling rate your recording software

supports, up to 96kHz at a bit width of 24-bits, and at 16- or 24-bits with a sampling rate of 48kHz or less. An ASIO control panel included

with your driver software allows you to set the OmniStudio USB to its different operating modes.The OmniStudio USB has several

operating modes, and when using the included ASIO drivers it will function as a 4-in, 4-out audio device. On the PC, the ASIO drivers,

as well as the Windows WDM/MME drivers, will load automatically during the driver installation procedure.

6. Theory of Operation