Harman Kardon HK6900 - Front Panel Controls - Part 1; Direct Signal Path and Loudness Features

HK6800/6900 Front Panel Controls
O POWER switch
The POWER switch turns the unit on and off. In North
American and Japanese versions, this switch also controls
power to the SWITCHED outlets on the back of the unit.
When the power to the unit is off, the switched outlets are
also turned off.
Q PROTECT light
This light indicates that the protection circuitry of your
amplifier is engaged. The light will come on under two
circumstances:
• When you turn the unit on. As the unit prepares itself for
operation, a muting circuit temporarily prevents pops or
other noise from reaching your speakers. When the unit is
ready for operation (in approximately 10 seconds), the light
will go off.
• When the unit detects a problem. This light will come
on if your speakers wires are touching, causing a short
circuit, or if your amplifier overheats. In the case of
overheating, a thermal sensor will shut down the unit
before damage can occur. Depending on the cause and
extent of the overheating, the unit may take some time to
cool down, and the protection circuit will remain in
operation until the unit is cool enough to operate safely.
In the case of a short circuit in the speaker wires, the
protection circuitry will attempt to reset itself every 10
seconds, and you may hear a slight click as it does so.
The protection circuit will remain in operation until the
condition is corrected.
©headphone jack
Stereo headphones with a standard 1/4" plug can be
connected to this jack. You can listen to headphones
regardless of whether your speakers are playing. To listen
to headphones only, turn the speaker selector to “OFF.”
©MAIN DIRECT
When the MAIN DIRECT switch is on, the source signal
goes directly to the input of the amplifier, bypassing all tone
controls and other preamplifier circuitry and is attenuated
only by the volume control. The indicator light will be lit
when the MAIN DIRECT switch is on.
© PHASE CORRECT LOUDNESS
At low volume levels, your ear is less sensitive to very low
bass frequencies than it is at normal listening levels. The
loudness button provides a special equalization curve that
boosts low frequencies. The loudness button is useful for
restoring full frequency balance at low volume levels, and
can also be used to improve the bass response of small
bookshelf speakers. The indicator light will be lit when
PHASE CORRECT LOUDNESS is on.
0 SUBSONIC filter
Warped records and turntable resonance can generate
sub-audible frequencies that can cause your speaker’s
woofer cones to visibly flutter. This very low frequency
noise, while inaudible, can rob power from your amplifier,
can cause feedback through your turntable, can cause
intermodulation distortion at audible frequencies, and can
actually damage your woofers if the movement is violent
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