Knoll 21K User Manual

21K Stereo amplifier specifications

Inputs: Gold RCA jacks with adjustable gain
Input impedance: 50k ohms
Outputs: 5 way gold insulated binding posts
Output power: 90 watts RMS per channel (8 ohms)
Ideal impedance: 4 – 8 ohms
Frequency response: 10 Hz – 40 kHz +/- 1dB
S/N ratio: Over 106 dB A weighted (90 watts)
THD distortion: Less than 0.1% 20 Hz to 20 kHz
IMD distortion: Less than 0.01% 60 Hz 7 kHz 4:1 (SMPTE)
Dimensions: 17” x 3.5” x 11.5” (432 x 89 x 292 mm)
Fan noise: No fan needed
Power: Maximum 320 watts at 117 VAC 60 Hz
Weight: 20 lbs
Construction: Steel chassis, powder coated; glass epoxy
printed circuit boards
Rack version: 21k-Rack

Three Year Limited Warranty

Knoll Systems warrants 21K amplifiers sold in the USA or Canada by authorized
Knoll dealers to be free from defects in materials and workmanship. This
warranty extends for three full years from the date of purchase by the
consumer. Any products returned freight prepaid to Knoll Systems and found to
be defective by Knoll Systems within the warranty period will be repaired or
replaced at Knoll Systems option, at no charge. Knoll Systems will not be
responsible for the actual cost of installation or removal of the product, nor for
any consequential or incidental damages. Some states do not allow the
exclusion or limitation of incidental or consequential damages, so the above
limitation or exclusion may not apply to you. This warranty gives you specific
legal rights. You may have additional rights, which vary from state-to-state.
Knoll products sold outside of the USA and Canada may be covered by
warranties provided by an authorized Knoll distributor. Please contact the
distributor in the country that the Knoll product was purchased.

Knoll Systems www.knollsystems.com
145 Tyee Drive Point Roberts, WA 98281
12140 Horseshoe Way Richmond BC V7A 4V5
Telephone [phone], Fax [phone]

Made in Canada

, © 2005, All Rights Reserved

21K

Stereo Amplifier
Installation Instructions

Caution: To reduce the risk of electrical shock, do not remove

the cover (or back). No user serviceable parts inside. Refer to
qualified service personnel.

Warning: To reduce the risk of fire or electric shock, do not
expose this appliance to rain or moisture.

The lightning flash with arrowhead, within an
equilateral triangle, is intended to alert the user to the

presence of uninsulated “dangerous voltage” within
the products that may be of sufficient magnitude to constitute a
risk of electrical shock to persons.

The exclamation point within an equilateral triangle is
intended to alert the user to the presence of
important operation maintenance (servicing)

instructions in the literature accompanying the appliance.

v1.1

Important Safety Instructions:

1) Read these instructions.

2) Keep these instructions.

3) Read all warnings.

4) Follow all instructions.

5) Do not use this apparatus near water.

6) Clean only with dry cloth.

7) Do not block any ventilation openings. Install in accordance with the
manufacturer’s instructions.

8) Do not install near any heat sources such as radiators, heat registers,
stoves, or other apparatus (including amplifiers) that produce heat.

9) Do not defeat the safety purpose of the polarized or grounding-type plug. A
polarized plug has two blades with one wider than the other. A grounding type
plug has two blades and a third grounding prong. The wide blade or the third
prongs are provided for your safety. If the provided plug does not fit into your
outlet, consult an electrician for replacement of the obsolete outlet.

10) Protect the power cord from being walked on or pinched particularly at
plugs, convenience receptacles, and the point where they exit from the
apparatus.

11) Only use attachments/accessories specified by the manufacturer.

12) Use only with the cart, stand, tripod, bracket, or table specified by the
manufacturer, or sold with the apparatus. When a cart is used, use caution
when moving the cart/apparatus combination to avoid injury from tip-over.

13) Unplug this apparatus during lightning storms or when unused for long
periods of time.

14) Refer all servicing to qualified service personnel. Servicing is required
when the apparatus has been damaged in any way, such as power-supply
cord or plug is damaged, liquid has been spilled or objects have fallen into the
apparatus, the apparatus has been exposed to rain or moisture, does not
operate normally, or has been dropped.

15).Under no circumstances should the output terminals of the amplifier be
short-circuited.

16).Be sure that the loudspeakers connected can handle the output power of
the amplifier at the loudspeakers rated impedance. The warranty on the
amplifier does not cover damage to loudspeakers that have inadequate
power handling capabilities.

17) Where an all-pole MAINS SWITCH is used as the disconnect device, the
location on the apparatus and the function of the switch shall be described,
and the switch shall remain readily operable;

18) A push button is used to turn the power off and on.

19) A LED is used to show when the apparatus is powered on.

CAUTION: These servicing instructions are for use by qualified service
personnel only. To reduce the risk of electric shock do not perform any
servicing other than that contained in the operating instructions unless you
are qualified to do so.

Suggestion #3

Poor grounding of the electrical system in your home may also
cause ground loop problems, particularly when there are
multiple components with three prong, grounded, power cords.
Unplug these components one at a time, and see if one or all of
them is causing the problem. The ultimate solution to this type
of problem is to rewire your house with an isolated, star type­grounding configuration. Knoll understands that this may be
impractical and expensive. In some instances, the use of an
approved AC Power Isolation Transformer (Knoll model PLB200)
of sufficient capacity may solve this problem.

Warning: If you suspect that the grounding system in your
home’s electrical wiring is causing the hum problem, it is
important that you do not make any changes to the wiring. Only
a licensed electrician should make any changes to household
wiring, and they must be made in full compliance with all local
building, safety and electrical codes.

Suggestion #4

Faulty earth grounds may also cause hum in your home’s
electrical system. In the past, cold water pipes were often used
for the earth ground, so it is important to make sure that your
ground connection is working properly and has not become
loose or corroded. The cold water pipe method may no longer
be valid in some areas due to requirements that the water
meter be isolated for the water mains with a length of PVC pipe,
therefore interrupting the ground circuit. The safest and most
reliable approach may be to provide your own ground. This can
be accomplished by having a licensed electrician drive at least
five feet of copper-jacketed steel grounding rod into the earth,
and using that for your grounding connection. If the hum
persists after all of the above suggestions have been tried,
contact Knoll’s Technical Support department for assistance.

Do not use this amplifier near water including near a bathtub,
swimming pool or hot tub.

This unit should be installed so that its location does not
interfere with proper ventilation. For example, don’t place the
amplifier on a bed, sofa, rug, or similar surface that may block
the ventilation openings; or place in a built-in installation such
as a bookcase or cabinet that may block the flow of air through
its ventilation openings.

The unit should be set away from heat sources such as
radiators, heat vents, or other devices (including amplifiers)
that produce heat.

The unit should be connected to a power supply outlet only of
the voltage and frequency marked on its rear panel.

The power supply cord of the unit should be unplugged from the
wall outlet when it is to be unused for a long period of time.

Care should be taken so that objects to not fall, and liquids are
not spilled, into the enclosure through any openings.

The unit should be serviced by qualified service personnel when:

• The power cord or plug has been damaged; or objects
have fallen, or liquid has been spilled into the unit.

• The unit has been exposed to rain, or liquids of any kind;
or the unit does not appear to operate normally, or
exhibits a marked change in performance.

• The amplifier has been dropped, or the enclosure
damaged.

To prevent electric shock, do not use the polarized plug with an
extension cord, receptacle or other outlet unless the blades can
be fully inserted to prevent blade exposure.

Introduction:

stereo power amplifier and congratulations on your choice. This
amplifier is specifically designed to be the best sounding
amplifier available anywhere. Our engineers and designers
spent years of pain staking research and testing to perfect the
sound quality. We hope you will appreciate this effort and enjoy
the amp.

Unpacking:

your new amplifier were specially designed to protect it from the
shock and vibration of shipping. We suggest that you save the
carton and packing materials to use if you move, or if the unit
ever needs to be shipped back to us for any reason. Should you
discover that your amplifier has been damaged during shipping,
please contact your dealer or Knoll immediately and request the
name of the carrier so a written claim can be made.

The right to a claim against a public carrier can be forfeited if the
carrier is not notified immediately in writing and if the shipping
carton and packing materials are not available for inspection by the
carrier. Save all packing materials until the claim is settled.

Thank you for your purchase of a Knoll 21K

The carton and packing materials used in shipping

Placement

During normal home operation the amplifier will become warm.
However, there are instances during high-level playback into
low impedance speakers when the amplifier will become much
warmer than normal. To ensure the amplifier’s trouble-free
operation, it is necessary to provide adequate ventilation. Your
amplifier should be kept away from external sources of heat
such as radiators and hot- air ducts. The amplifier should never
be placed with other heat-producing components in a cabinet or
enclosure lacking free airflow. Do not stack other components
on top of your amplifier.

Rack mounting

A rack mount version of the 21K is available. For best operation
when rack mounting the 21k we suggest it be near the top of
the rack and have vented blank 1 rack space panels above and
below the 21k. For multiple 21k amps in one rack we suggest
spacing the amps 1 rack space apart and inserting a vented
blank 1-rack space panel between each amp.