M-AUDIO OmniStudio USB - Manual (Page 12)

There are some basic concepts that apply to all audio gear. Understanding them will help in your operation of the OmniStudio USB, as well
as create a set of common terms to use in our discussion of the OmniStudio USB components.
A “balanced” line runs the signal on two wires of opposing polarity, as a ‘twisted pair’ surrounded by a grounded shield. Doing so, it can
send a ‘hotter’ signal over a longer distance with less added noise. Using a TRS (tip-ring-sleeve, or stereo) plug on the 1/4” jacks of the
OmniStudio USB (designed for unbal/balanced operation) will give you this balanced line—tip positive, ring negative, and sleeve ground.
Generally, if the OmniStudio USB outputs connect to a system or device that accepts a balanced line at +4dB (nominal level) operating level,
you should use TRS plugs on the outputs. XLR connectors also carry a balanced signal. If your device or monitoring system accepts an XLR
connector, you may need a cable that has 1/4” TRS to male or female XLR. The OmniStudio USB Mic/Instr Inputs accept a male XLR, with a
balanced mic cable being female XLR to male XLR.
Unbalanced Signals
An unbalanced line on the OmniStudio USB outputs connects to a 1/4” TS (tip positive, sleeve ground) plug on a shielded cable with a single
conductor, and is appropriate to use when the device you are connecting to accepts a 1/4” TS plug or an RCA plug. Typically, the signal
on unbalanced lines has an operating line level of -10dB (nominal level), though this varies somewhat. You may want to consult the user
guide of your sound card or sound system if you’re not sure what type of signal it can accept. If you need to, find a primer on recording
or sound reinforcement to learn more about this and the other subjects covered in this manual.
Phantom Power
Unlike dynamic microphones, most condenser microphones need to receive a DC voltage (generally +48V) from an external source
before they can generate an output signal. If the condenser mic doesn’t come with its own power supply, then phantom power must
be applied from the OmniStudio USB’s Mic/Instr pre-amps. Pressing the Phantom Power button and engaging phantom power on the
OmniStudio USB will send the necessary voltage to both of the XLR Mic Inputs. Phantom power will not affect a dynamic mic adversely,
so its not a problem to have a dynamic mic connected to the XLR input while phantom power is switched on. Some ‘ribbon’ microphones
(particularly older models) may be harmed, however, so check your microphone’s documentation.
Sends and Returns
These are sometimes elusive terms, as they can be used in a variety of ways. A “send” is generally an output from a device (such as a
mixing console), to another device (which might be considered “outboard”). There is some expectation that the signal that is sent from
the send output is going to “return” to the sending device’s signal flow. A return is an input to a device. Note that these sends and returns
may be completely virtual (that is, software-based) – in fact, the entire mixer, as well as the outboard device(s) may also be software-based.
Sends and returns are generally spoken of in terms of the gear that is receiving the signal. The “effects send,” therefore, is an output
from the mixer to the effect. The effect’s input receives the signal from the “effects send,” and the output of the effects device returns
the signal to the mixer’s input, the “effects return.” The terms “sends and returns” can apply to other devices, such as a recording
device. The outputs of mixing board are “sent” to a tape deck, for instance, and the outputs of the tape deck “return” to the mixing
desk’s monitor channels for mixing (often called “tape returns,” though “tape sends” are more often known as the bus outs).
7. Operational Basics and Definitions
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