M-Audio EX66, Руководство пользователя

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EX66 User Guide » 7
Protection Circuits
In order to safeguard your EX66 from accidental damage, we’ve
built in some protection mechanisms.
Overload Protection
The EX66 can react to two types of electrical issues: “over-current”
and “over-voltage.” In the case of the former, when the system is
driven so hard that it approaches the upper limit of the drivers’
piston range, the output waveform will soft clip (at 11 amps) in
order to protect the drivers. We’ve even taken further precautions
to protect the drivers by exploiting the 6th-order alignment
(referenced earlier) with a 2nd-order high-pass filter that limits
excessive excursion at low frequencies that might otherwise cause
the voice coil to hit the back plate of the driver. In the case of
an over-voltage condition (where the AC power to the monitor
exceeds safe limits), the EX66 automatically activates a circuit that
mutes the output and draws no current until the over-voltage
condition is remedied.
Thermal Protection
Have you ever noticed that most power amplifiers use big heat
sinks? These are necessary because traditional power amplifiers
generate quite a bit of thermal energy that has to be dissipated
away from the output transistors. While all amplifiers generate and
dissipate heat, our PWM architecture is particularly efficient in that
there is very little wasted energy—so the EX66 produces relatively
small quantities of heat. Nevertheless, we’ve taken precautions to
prevent the [unlikely] possibility of overheating. If the power amp
gets too hot, the over-temperature circuit mutes the output to
allow the heat to dissipate to a normalized hysteresis level, at which
time the EX66 will start up again. If your EX66 happens to overheat
and activate the thermal protection circuit, you probably need to
examine your speaker placement and setup to make sure there’s
nothing obstructing airflow around the cabinet.
Magnetic/Video Shielding
Many of our customers are computer-centric musicians or film/TV
score composers, so we’ve made sure that all of our loudspeaker
monitors are designed to be used next to traditional video monitors
(containing cathode ray tubes). While the EX66 drivers do contain
fairly sizeable magnetic structures, they’re also shielded so that the
B-fields they generate don’t interfere with adjacent video
monitors.
Protecting Your Ears
As a musician, composer, or engineer, your hearing is one of your
most valuable assets. So we’d like to advise you about protecting
yourself from high sound pressure levels (SPLs), which can lead
to hearing loss. It is interesting to note that while hearing loss
is a common occupational illness, people often ignore it because
there are no visible effects, most often it develops over time, and
usually there is no pain. But we believe it’s critical to protect your
hearing because good hearing is so essential to communication,
socialization, responsiveness to the environment, and—perhaps
most importantly—the enjoyment of music.
Please be aware that the EX66 monitors are capable of generating
very high SPLs over sustained periods of time; but because these
monitors have very low levels of distortion (even at high volumes),
you may not always notice that the sound level is high while working
with them. Health experts say that levels over 90dB for 8 hours per
day can eventually cause permanent hearing loss. According to the
US Government’s Occupational Safety and Health Administration
(OSHA) and the National Institute on Deafness (NIDCD), you
should limit your exposure using the following guidelines, lest you
risk losing your hearing:
<
90 Decibels : avoid prolonged exposure at this level
(examples: small jazz trio; piano fortissimo;
train whistle at 500 ft.)
<
100 Decibels : no more than 15 minutes at this level
(examples: very loud orchestral music;
wood shop)
<
110 Decibels : avoid unprotected exposure of more than
1 minute (examples: front row of a loud
rock concert; chain saw)
If you plan to use the EX66 monitors regularly at high volumes,
we recommend you periodically use a sound level meter capable
of integrating the sound level over a period of time according to
noise control standards. This way you can check to make sure your
listening levels are always within safety limits.
Do You Know...?
...what Bill Clinton and Pete Townshend (of The
Who) have in common?
They both have hearing damage from exposure to
loud music.
( President Clinton played saxophone in a loud
band as a teenager, causing him mild but
permanent hearing loss; he was eventually fitted
with a hearing aid in 1997—which he said he
needed in order to make out what hecklers were
shouting at him during his speeches. By contrast,
Pete Townshend is now almost completely deaf
from years of exposure to loud music; he can no
longer hear normal conversational speech.)
Concluding Remarks
M-Audio is committed to developing active loudspeaker monitors
for those who demand the most accurate and transparent sound.
We believe a well-designed speaker should be both revealing and
absolutely effortless to work with—making your job easier and
more enjoyable. We encourage you to compare our EX series
monitors with any others on the market, and we trust you’ll agree
they’re unbeatable for natural (and great-sounding) reproduction.