To increase the speaker loudness two-fold takes ten times the power. A speaker
rated at 94db will produce this level from I Watt at 1 meter's distance from
the cabinet. As the sound travels away from the loudspeaker cabinet, the dB
(Decibel) level also decreases. This in turn requires more power to maintain
a specific dB level at a given distance from the cabinet.
Watts (Power)
The smallest increase in loudness of 3dB takes twice the power. To increase
the level to seem twice as loud, you need ten times the power. If you try to
sustain a given loudness within a particular room size and do not have enough
power (watts), several things begin to happen within your sound system. As you
use up amplifier headroom, the sense of detail in the reproduced sound will
disappear. Then you may hear distortion on signal peaks - the distortion is
generally easier to hear at higher frequencies, but is much more common at low
(bass) frequencies. This means the amp is running short of power to send to
the speakers. Allowing this state to continue will reach the third stage of
failure, overt distortion followed by voice coil burnout. Many people have an
amazingly high tolerance for distortion and just do not notice a problem until
it is too late.
IMPORTANT NOTE
Never turn on the amplifiers (or other source units) with the level (volume)
control on at any level. This could cause irreparable damage to your loudspeaker
system. This is normally detected by a loud pop when the units are switched
on. If this occurs with the level controls down, turn off your system immediately
and consult your dealer. Never use an amplifier with a higher rating than your
speaker system. This could cause damage to your speaker system. If in doubt
consult your dealer. Do not use shielded or microphone cable for any speaker
connection as this will not handle the amplifier load and could cause damage
to the complete system.
Improper Operation
It is easy to damage loudspeakers by overdriving them. This happens when you
turn the volume control up too far, causing distortion. Most failures resulting
from improper operation can be traced to over or under powering the loudspeakers.
When an amplifier is underrated in power and turned up too loud, it is unable
to supply more clean power to the loudspeakers, resulting in a distorted signal
being passed to the loudspeaker. The cones or diaphragms are then unable to
produce the full excursion required to reproduce the signal they are trying
to achieve. The speaker cone or diaphragm becomes unstable with no power left
to propel it forward or pull it back, and heat builds up on the voice coil.
Normally, this heat is dissipated through the loudspeaker's vents and by conduction
along the former, aided by the motion of the whole assembly through the cooler
air. Changes and gaps in the signal level provide a rest offering some brief
respite to allow radiant and conductive cooling. Even a few watts of power can
cause a rapid and damaging build up of heat under these conditions. A sustained
level of even a few watts of distorted power is always fatal to loudspeaker
components. Remember, if you are losing detail or hear distortion, TURN IT
DOWN To prevent loudspeaker damage and obtain a louder sound, use more powerful
amplifiers and/or more speaker cabinets. This is entirely dependent upon the
level of sound desired and room size. The two possible solutions are: 1. Use
a more powerful amplifier - one with a rated output that DOES NOT exceed the
power rating of the speakers 2. Use more speaker cabinets - in the correct series-
parallel arrangement to match the required impedance load of the amplifier.
Speaker Power Ratings
By far the most common cause of loudspeaker failure is damage to the voice
coils caused by amplifier overload. Speaker damage from faulty components
or manufacturing defects is very rare. The overwhelming majority of failures
are due to misunderstanding the difference between loudness (decibel, dB) and
the power to create it (Watts, W).