trimVLZ
In audio mixers, the gain adjustment for theAcronym for very low impedance.
first amplification stage of the mixer. The trim(Impedence is measured in ohms represented
control helps the mixer cope with the widelyby the W symbol, which is the last letter of the
varying range of input signals that come fromGreek alphabet. This is how the letter Z is
real-world sources. It is important to set theused instead of I.) VLZ is one of the most im-
trim control correctly; its setting determinesportant reasons why inherent noise levels on
the overall noise performance in that channelMackie mixing boards are so minuscule. Ther-
of the mixer. See mic preamp.mal noise is something thatOs created by all
TRScircuitry and usually transistors and resistors
Acronym for Tip-Ring-Sleeve, a scheme forare the worst culprits. The basic rule with
connecting three conductors through a singlethermal noise is: the higher the impedance,
plug or jack. 1�4" phone plugs and jacks and 1�8"the more the noise. MackieOs VLZ design re-
mini phone plugs and jacks are commonlyduces thermal noise by making internal
wired TRS. Since the plug or jack can carryimpedances as low as possible in as many
two signals and a common ground, TRS con-places as possible within the console. VLZ is
nectors are often referred to as stereo orachieved by scaling down resistor values by a
balanced plugs or jacks. Another common TRSfactor of three or four � resulting in a corre-
application is for insert jacks, used for insert-sponding reduction in thermal noise. This is
ing an external processor into the signal path.especially true for the consoleOs mixing buses.
In Mackie mixers the tip is send, ring is return,volume
and sleeve is ground.Electrical or sound level in an audio system.
TSPerhaps the only thing that some bands have too
Acronym for Tip-Sleeve, a scheme for con-much of.
necting two conductors through a single plugVRMS
or jack. 1�4" phone plugs and jacks and 1�8" miniSee RMS.
phone plugs and jacks are commonly wired TS.wet
Sometimes called mono or unbalanced plugsWith added reverberation or other effect
or jacks. A 1�4" TS phone plug or jack is alsolike echo, delay or chorusing.
called a standard phone plug or jack.XLR connector
unbalancedSee Cannon.
An electrical circuit in which the two legs of
the circuit are not balanced with respect to
ground. Usually, one leg will be held at ground
potential. Unbalanced circuit connections re-
quire only two conductors (signal Ohot� and
ground). Unbalanced audio circuitry is less
expensive to build but under certain circum-
stances is more susceptible to noise pickup.
unity gain
A circuit or system that has its voltage gain
adjusted to be one, or unity. A signal will leave a
unity gain circuit at the same level at which it
entered. In Mackie mixers, unity gain is
achieved by setting all variable controls to the
marked OU� setting. Mackie mixers are opti-
mized for best headroom and noise figures at
unity gain.
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ACEC
