Allen&Heath XONE 62 - Manual (Page 28)

28 XONE:62 User Guide
DJ Disc Jockey. The console operator sequencing
and playing the music tracks. Some simply play the
tracks, others talk over with introductions and
announcements, and others provide an entertaining
performance by mixing and shaping sounds to
create a completely different musical experience.
Drum Machine An electronic drum simulator as
used by keyboard players and in electronic music.
This now provides another DJ tool to create an
alternative beat to mix in with the music.
Dynamic Range The difference expressed in dB
between the highest and lowest signal levels
possible. This is limited by the clipping level and
residual noise floor respectively.
Earth Also known as ‘ground’. The term for the
electronic signal reference. This connects to the
mains supply earth point and all cable shields and
conductive equipment cases. It provides the return
for the signal voltage within the equipment. It also
ensures operator safety by removing the possibility
of electric shock should the mains voltage touch any
metal part.
Earth Loop The result when the equipment sees
more than one path to the system earth. Current
flows because a resistive loop susceptible to radio
and mains interference is formed. This can result in
audible hum or buzz in the system.
Equaliser (EQ) This provides cut or boost of
selected frequencies (equalisation) for tonal shaping
of the sound. This is similar to the bass and treble
controls of domestic hifi amplifiers. However, XONE
provides 4 independently controllable frequency
bands for corrective or effective sound shaping.
Feedback Also known as ‘howlround’ or ‘ringing’
this is the rapidly increasing tone produced when a
microphone picks up its own signal from the
speakers. It is usually a shrill and annoying squeal
that should be quickly dealt with by reducing mic
gain or equalising the system to notch out the
offending frequencies.
Gain This is the boost or attenuation applied to the
source signal in the channel preamp stage to match
it to the console operating level. For example, a
large amount of gain is need to match low
microphone signals. It is set using the console
meters. Gain is not used for level (volume) control.
Headroom The amount of level available
expressed in dB to handle peaks above the normal
0dB operating level.
Hz Hertz. The measurement of frequency. The
audio spectrum ranges from a low (bass) frequency
of 20Hz to a high (treble) 20kHz. Not many sound
systems reproduce the full range. Average hearing
does not extend much beyond 15kHz or so.
Response is further impaired if the ear is subjected
to continual high sound pressure levels.
Highpass A filter that attenuates frequencies
below the cut-off frequency.
Hum Apart from not knowing the words… this is
the audible noise that usually results from mains
interference pickup, earth loops, bad
interconnections and induced power supply and
lighting fields. It is usually at mains frequency
(50/60Hz) or a related harmonic.
Impedance (Z) A technical term for the resistance
of a signal conductor to ground. Low impedance
usually refers to microphones of 200 ohms or less,
and line signals typically less than 100 ohms. Low
Z sources are less prone to interference pickup.
Inputs are usually high impedance so that one
source can connect to more than one channel
without signal loss. Note that the operating
impedance of a connection is set by the impedance
of the source, not that of the unconnected input.
Impedance balanced Refers to the type of output
signal connection. Has three conductors, two for
signal and a shield which is connected to earth.
Provides interference rejection similar to a fully
balanced connection because the two signal
conductors are matched at the same impedance.
However, the drive capability is less because the
signal is carried by only one conductor.
Limiter A signal processor that limits the maximum
level possible by preventing the signal going over a
predetermined threshold level. This is very useful in
club installations where it is inserted between the
console and house system amplifiers to prevent the
DJ exceeding the maximum allowable volume.
Lowpass A filter that attenuates frequencies
above the cut-off frequency.
MC Master of Ceremonies. The presenter who
introduces the performances and maintains the
running order.
MiniDisc A type of low cost digital 2-track recorder
that uses a disc similar to but smaller than that used
by computers. It records up to 74 minutes of stereo
material and is regarded as the modern
replacement for the audio cassette recorder. It has
the added facility to label and edit tracks.
Mono The left and right stereo signals summed
together as one.
Mute To turn off the signal.
Noise Generic term for an unwanted signal. This
may be residual electronic hiss, hum, buzz, clicks
and pops, or simply loud undesirable music.
Noise Floor This is the term for the residual
electronic noise produced by all powered audio
equipment. It usually sounds like a constant hiss,
although some equipment may suffer from residual
hum as well.
Omni-directional The response of a microphone
which picks up sounds equally all round. Not suited
to live vocal applications as they are more prone to
feed back.