Operating instructions

Glossary of Terms
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Internal clock - A clock signal derived from onboard circuitry. (see “Clock”)
I/O - Short for “input/output.”
kHz - Short for “kiloHertz” (a thousand Hertz), a unit of measurement describing a thousand analog audio
cycles (or digital samples) per second. (see “Hz”)
Jitter - Refers to short-term variations in the edges of a clock signal, caused by a bad source clock, inferior
cabling or improper cable termination, and/or signal-induced noise. A jittery signal will contain spurious
tones at random, inharmonic frequencies. Usually, the jitter will be worse with higher signal frequencies.
The internal digital clock of the 2192 was designed for extreme stability and jitter-free operation, and its
onboard phase aligned clock conditioner circuitry removes jitter from external sources, so conversion
quality is unaffected by clock source.
Light pipe – A digital connection made with optical cable. This was a phrase coined by Alesis to make a
distinction between the proprietary 8-channel optical network used in their ADAT products and standard
stereo optical connectors used on CD players and other consumer products.
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 semiprofessional audio equipment typically utilize line level signals of
-10 dBV (which translates to 0.316 volts).
Mic level - Refers to the very low level signal output from microphones, typically around 2 millivolts
(2 thousandths of a volt).
Native - Refers to computer-based digital audio recording software controlled by the computer’s onboard
processor, as opposed to software that requires external hardware to run.
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.
Pro Tools - A popular and widely used computer-based digital audio workstation developed and
manufactured by Digidesign. The most current system, Pro Tools | HD, provides hardware and software that
supports multiple channels of high resolution digital audio, at sampling rates of up to 192kHz. (see
“Sample rate”)
Quantization noise - A form of digital distortion caused by mathematical rounding-off errors in the analog
to digital conversion process. Quantization noise can be reduced dramatically by dithering the digital
signal. (see “Dither”)
Sample - A digital “snapshot” of the amplitude of a sound at a single instant in time. The number of
samples taken per second is determined by the device’s sample rate. (see “Sample rate”)
Sample rate - The number of samples per second. In digital audio, there are six commonly used sample
rates: 44.1 kHz (used by audio CDs), 48 kHz, 88.2 kHz (2 x 44.1 kHz), 96 kHz (2 x 48 kHz, used by DVDs),
176.4 kHz (4 x 44.1 kHz), and 192 kHz (4 x 48 kHz). The higher the sample rate, the greater the frequency
response of the resulting signal; however, higher sample rates require more storage space. (see “kHz”)