Technology Brief Understanding Relationships Voltage-Current-Impedance

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Technology Brief: Designing for Great Performances
Terms & Abbreviations
dB: The dB symbol represents the decibel, a unit of measurement
that expresses levels for audio electronics, RF signals and
communications. The dB is a logarithmic unit for a ratio that can be
used for power, sound pressure level, voltages or intensity.
d: The distance between a speaker and a listener position or target
audience location. Sound decreases in level 6dB for every doubling
of distance or ‘d’ from the speaker.
E: The symbol E represents the voltage or electrical pressure of the
electrons in a circuit and its unit of measure is the volt. The symbol V
in used interchangeably.
I: The symbol I represents the current or rate of ow of electrons in a
circuit and the unit of measure is the ampere that’s also abbreviated
as amp.
Ohms: The resistance of an electrical circuit measured with voltage
and current present where the ratio of voltage to current (V/I)
is always the same for the same resistive R material. The ratio is
called resistance, measured in ohms and expressed as R = V / I or
algebraically E = IR and I = E/R.
P
AMP
: The output power of an amplier.
P
NOM
: The nominal amplier power. When matched with a load this
power level provides sufcient SPL for operational requirements.
P
MAX
: The maximum power produced. This level should provide the
speaker with the maximum power within the units safe operating
area limit.
P
SPKR
: Amplier power expressed in watts that’s delivered to the
speaker.
Power: Power is based on Joule’s & Ohm’s Laws, expressed in
watts: P = I2R; P = IE; P = E2/R
R
LOAD
: The total resistance or impedance of the load including all
intermediary connections between the amplier output and speaker.
R or Resistance: R represents the Resistance of a circuit and its unit
of measure is the ohm.
RMS: Root Mean Squared can be thought of as a time average
measure of magnitude of the power producing effect of the signal
voltage.
SPL: Sound Pressure Level is an acoustic measurement usually
expressed in dB. It is commonly dened using a reference which is
the approximate intensity at 1000 Hz , barely audible at the threshold
of hearing or which is zero phons.
V: The symbol V represents the Voltage or electrical pressure exerted
by the electrons.
V
MAX
: The maximum voltage at the amplier output.
V
NOM
: The nominal voltage at the amplier output.
Watt: The power produced by current owing to a voltage potential:
1 amp owing through a potential of 1 volt produces 1 watt.