Active Studio Monitor O 300 D
Page 7
The controls protected beneath the
plastic caps may not be
tampered with under any
circumstances!
1.7.6 GROUND LIFT
Since the input is transformer-balanced and
floating, you should rarely experience any
hum. In unusual cases, or if the source is
unbalanced, it may be necessary to lift the
connection between signal ground and
chassis ground, in which case you will find
this little switch convenient. The chassis
ground remains always connected to the
protective earth conductor.
Warning!
The protective earth conductor must
never be interrupted even for test
purposes! This may be dangerous to
life!
1.8 CONTROLLER
The O 300 D Studio Monitor includes controller
electronics (limiter and analog filtering) that are
finely tuned to match its three drivers. In order to
be compatible with future developments (such
as FIR - filter technology), a connector for
external controllers was included. Using this
connection renders the internal D/A converters,
analog input stages, filters and limiters inactive,
with the sole exception of the bass peak limiter.
For optimal power amp utilization even under
varying voltage conditions and loads, the peak
limiter in the woofer channel was left in, but the
thermo limiter is deactivated.
1.8.1 CONTROLLER SELECT Switch
This switch is used to deactivate the internal
controller. By way of the jack labeled
POWER - AMP DIRECT INPUT
you can feed in signals intended for the three
internal power amplifiers. This 7-pin female
XLR jack is wired as follows:
Pin 1 = woofer input +
Pin 2 = woofer input -
Pin 3 = midrange input +
Pin 4 = midrange input -
Pin 5 = tweeter input +
Pin 6 = tweeter input -
Pin 7 = ground
1.9 Display functions
The illuminated K+H logo serves as a status
indicator for the loudspeaker cabinet.
Constant red:
Normal operation, internal
power in order
Blinking red:
Overload protection circuitry
engaged
If the light is blinking, this indicates that the
overload-protection circuitry has been triggered,
as may happen while cuing up a tape deck or
while running sine wave signals through the
speakers for measurement purposes. Output
power is reduced to a level that takes the
speakers out of danger. If this happens, you must
search for the cause and possibly reduce the
monitoring level.
1.10 Front grille
A front grille for the speaker baffle is not included
as standard equipment, but one is available as
an option. This fine mesh metal grille (article
GO 300) is easy to attach and offers added
protection to the exposed components. The
acoustical effect on the speakers is minimal and
can only be detected at all with test equipment.
1.11 Care of the cabinet
The cabinet housing of the K+H O 300 D active
studio monitor is available in either a flocked or
enamel finish (charcoal: RAL color 7021). With
the flocked housing, a certain amount of “hair
loss” within the first few weeks is normal, and
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Figure 3 Effects of room compensation on
frequency
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