17
Impedance
- A description of a circuit’s resistance to a signal as measured in ohms, thousands of
ohms (K ohms), or millions of ohms (M ohms). The symbol for ohm is
Ω
.
kHz
- Short for “kiloHertz” (a thousand Hertz), a unit of measurement describing a thousand analog
audio cycles (or digital samples) per second. (See “Hz”)
Line Level
- Refers to the voltages used by audio devices such as mixers, signal processors, tape
recorders, and DAWs. Professional audio systems typically utilize line level signals of +4 dBm (which
translates to 1.23 volts), while consumer and semi-professional audio equipment typically utilize line
level signals of -10 dBV (which translates to 0.316 volts).
Low Cut Filter
- An equalizer circuit that cuts signal below a particular frequency.
Low Shelving Filter
- An equalizer circuit that cuts or boosts signal below a specified frequency, as
opposed to boosting or cutting on both sides of the frequency.
Mic Level
- Refers to the very low level signal output from microphones, typically around 2 millivolts
(2 thousandths of a volt).
Mic Preamp
- The output level of microphones is very low and therefore requires specially designed
mic preamplifiers to raise (amplify) their level to that needed by a mixing console, tape recorder, or
digital audio workstation (DAW).
Negative Feedback
- Negative feedback is a design technique whereby a portion of the preamplifier’s
output signal is reversed in phase and then mixed with the input signal. This serves to partially cancel
the input signal, thus reducing gain. A benefit of negative feedback is that it both flattens and
extends frequency response, as well as reducing overall distortion.
Patch Bay
- A passive, central routing station for audio signals. In most recording studios, the
line-level inputs and outputs of all devices are connected to a patch bay, making it an easy matter
to re-route signal with the use of patch cords.
Patch Cord
- A short audio cable with connectors on each end, typically used to interconnect
components wired to a patch bay.
Ribbon Microphone
- A type of microphone that works by loosely suspending a small element (usually
a corrugated strip of metal) in a strong magnetic field. This "ribbon" is moved by the motion of air
molecules and in doing so it cuts across the magnetic lines of flux, causing an electrical signal to be
generated. Ribbon microphones tend to be delicate and somewhat expensive, but often have very flat
frequency response.
Transformer
- An electronic component consisting of two or more coils of wire wound on a common
core of magnetically permeable material. Audio transformers operate on audible signal and are
designed to step voltages up and down and to send signal between microphones and line-level devices
such as mixing consoles, recorders, and DAWs.
Transient
- A relatively high volume pitchless sound impulse of extremely brief duration, such as a
pop. Consonants in singing and speech, and the attacks of musical instruments (particularly
percussive instruments), are examples of transients.
TRS
- A standard ¼” Tip-Ring-Sleeve (three-conductor) connector typically used for balanced signals.
XLR
- A standard three-pin connector used by many audio devices, with pin 1 typically connected to
the shield of the cabling, thus providing ground. Pins 2 and 3 are used to carry audio signal, normally
in a balanced (180
°
out of phase) configuration. Note that XLR only denotes the connector type and
not the signal level; XLR connectors can be (and often are) used for both mic-level and line-level
signals.
