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Getting to know the rear panel
A. Audio Inputs
Use the INPUT jacks to connect the outputs of a
preamplifier, receiver with pre-out connections, CD
player, or other control devices.
B. Input Gain Controls
Use these to adjust the input gain of each channel.
C. Product Serial Number
Write this number in the space provided on page
“” for
future reference.
D. Remote Trigger Input
Use the REMOTE TRIGGER jack to connect a compatible
preamplifier, source device, or other product with a
12VDC output (abut 35mA required).
E. Audio Outputs
This is an unbuffered line level output to other devices
such as another 21k amplifier.
F. AC Input
Use the included power cord to connect your amplifier to
an AC power source.
G. Speaker Outputs
Use the OUTPUT binding posts to connect the amplifier to
your speakers: red for positive, black for negative.
Connecting your amplifier
When making connections between any source components and
the amplifier, or when making connections to any speaker, be
certain that both the input devices and the amplifier are turned
off. Unplug all equipment before making any connections so that
there will be no unwanted signal transients that can damage
equipment or speakers.
Input connections
Connecting the 21K to your source equipment is
straightforward. Using the high-quality audio interconnect
cables, match the output channel designations on the rear of
your source equipment to the input jacks on the rear panel of
your amplifier that have the same channel name. When making
connections with RCA type plugs on interconnect cables, make
certain to gently, but firmly, insert the plug into the jack. Loose
connections can cause intermittent sound and may damage your
speakers. Some quality RCA plugs may be very tight, and it is
important to secure a proper connection between the
interconnection cable and the input jack.
Speaker connections
To ensure that the high quality signals produced by your
amplifier are carried to your speakers without loss of clarity or
resolution, Knoll advises that you use high-quality speaker wire.
Many brands of wire are available — the choice may be
influenced by the distance between your speakers and the
amplifier, the type of speakers you use, personal preferences,
along with other factors.
Regardless of the brand or type of speaker wire chosen, we
suggest that you use a wire constructed of fine, multi-strand
copper with a gauge of 14 or less (the lower the number, the
thicker the cable). Wire with a gauge of 16 may be used for
short runs of less than 12 feet. We do not recommend that you
use any wires with an AWG equivalent of 18 or higher due to
the power loss and degradation in performance that will occur.
To connect the amplifiers to your speakers, a pair of binding
posts is provided for each channel output. These posts will
accept bare wire, spade lugs, or banana type plugs. If bare wire
is used for the connections, strip approximately 1/2 inch to 3/4
inch of insulation from the end of each wire and carefully twist
the strands of each conductor together. Be sure not to cut the
individual strands or twist them off. All strands must be used for
optimal performance.
Correct polarity connections are important to maintain proper
speaker phasing. When speaker phasing is correct, all speakers
move in and out at the same time preserving the imaging of the
program material. Out-of-phase connections mean that some