Important Safety Instructions: Hum and noise
In most cases, one of the following suggestions should help you
solve a hum noise in your system. Please try these steps in the
order shown, proceeding from one step to the next if the prior
suggestion does not eliminate the problem.
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. Suggestion #1
7) Do not block any ventilation openings. Install in accordance with the manufacturer’s
instructions. To determine if a cable TV connection is responsible for the hum, first
turn off all the components. Disconnect the cable TV feed to your
system at the first place where it connects to your components.
Alternatively, disconnect the cable TV wire where it is connected at the
wall outlet. Turn your system back on, and listen if the hum has
disappeared. If removing the cable TV feed has eliminated the hum,
you will need to insert a Ground Loop Isolator (Knoll model GB634)
before reconnecting the cable TV feed, or contact your cable TV
operator to see if they can better isolate your cable feed.
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. Suggestion #2
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.
Turn off all components in your system and then disconnect the input
cables at the amplifier. Turn the amplifier back on to see if the hum is
still present. If the hum disappears, the fault may be in the input cables
used. Try replacing them with cables that have better shielding, and
make certain that the input cables are not running on top of any AC
power cords. Change the cables one at a time to determine if one or all
cables are responsive. If the hum disappears when the input cables are
disconnected but returns after the cables are changed and the system
reconnected, your source device may be causing the problem.
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.
Suggestion #3
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.
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 type-grounding 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.
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.
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.