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Set the rear panel voltage selector switch to match your local line voltage.
Alerts users to risks of electric shock, fire, and damage from moisture or improper use.
Connect to specified power supply; route cords to prevent pinching or damage.
Do not defeat grounding, ensure proper ventilation, avoid heat sources and water.
Avoid liquid spills, metal objects inside, and never remove the enclosure.
Refer servicing to qualified personnel for damaged cords, liquid spills, or malfunctions.
Guide to setting the impedance selector based on connected speaker impedance.
Table outlining common symptoms, causes, and remedies for operational issues.
Detailed technical specifications, including power output and distortion for North America.
Set the rear panel voltage selector switch to match your local line voltage.
Alerts users to risks of electric shock, fire, and damage from moisture or improper use.
Connect to specified power supply; route cords to prevent pinching or damage.
Do not defeat grounding, ensure proper ventilation, avoid heat sources and water.
Avoid liquid spills, metal objects inside, and never remove the enclosure.
Refer servicing to qualified personnel for damaged cords, liquid spills, or malfunctions.
Guide to setting the impedance selector based on connected speaker impedance.
Table outlining common symptoms, causes, and remedies for operational issues.
Detailed technical specifications, including power output and distortion for North America.
This document is an instruction manual for the Kenwood KM-991 stereo power amplifier.
The Kenwood KM-991 is a stereo power amplifier designed to provide high-quality audio reproduction. It is built with a focus on durability and performance, ensuring that users can enjoy their music with clarity and power. The amplifier is designed to be a central component in a home audio system, connecting to various audio sources and driving speakers to produce rich, detailed sound. Its robust construction and careful engineering reflect Kenwood's commitment to delivering a superior listening experience.
The KM-991 amplifier is designed for straightforward operation, allowing users to easily integrate it into their existing audio setups. Before connecting the unit, it is crucial to unpack it carefully and ensure all accessories are present. The instruction manual emphasizes the importance of checking the serial number, found on the back of the unit and on the warranty card, for record-keeping and potential service needs.
Connecting the amplifier involves several key steps. Users must first connect the unit to an appropriate AC outlet, ensuring that the voltage selector switch is correctly set for their region (e.g., 110-120V AC or 220-240V AC). For units shipped to the U.S.A. and Canada, a 120V AC supply is required, and a CAUTION is issued against using the AC plug with an extension cord, receptacle, or other outlet unless the blades can be fully inserted to prevent blade exposure. For units shipped to Europe, a 230V AC supply is needed, while other countries may require different voltage settings. The manual provides clear diagrams for AC voltage selector switch settings and plug wiring for different regions, including the United Kingdom, where specific wiring colors (Blue for Neutral, Brown for Live) are detailed.
Once the power is connected, the amplifier can be linked to other components of the audio system, such as a control amplifier (e.g., Kenwood KC-991) and speakers. The manual includes a detailed diagram illustrating system connections, showing how the power amplifier connects to the control amplifier and then to the AC outlet. It also highlights the use of unswitched AC outlets on the control amplifier, which are controlled by the power key on the main unit.
Connecting speakers is a critical step for optimal sound. The KM-991 supports two sets of speakers, A and B. The manual provides a visual guide for connecting speaker cords: push the lever up, insert the cord, and then lock the lever. It is essential to connect the positive (+) and negative (-) terminals correctly to avoid reversed polarity, which can lead to unnatural sound and poor imaging. The speaker impedance selector on the rear panel must be set according to the impedance of the speakers used (e.g., "LESS THAN 8 Ω" for 4 Ω or 6 Ω speakers, and "8 Ω OR MORE" for 8 Ω or 16 Ω speakers). This selector ensures proper power delivery and protects the amplifier. The speaker protection circuit automatically activates if the power switch is turned on with the speaker cord short-circuited, preventing damage.
The front panel of the KM-991 features several controls and indicators. These include the POWER switch, SPEAKERS A/B switches, POWER LEVEL METER, Headphones jack (PHONES), POWER INDICATOR, and METER RANGE knob. The SPEAKERS A/B switches allow users to select which set of speakers (A, B, or both) are active, or to silence all speakers for private listening through headphones. The POWER LEVEL METER displays the output power level, and the METER RANGE knob adjusts the sensitivity of this display.
Operating instructions are presented in a step-by-step manner. To listen to a program source, users first switch on the power, then select an input source on the control amplifier, adjust the volume on the control amplifier, and finally adjust the tone on the control amplifier. For listening through headphones, users insert the headphone plug into the headphones jack, ensure the SPEAKERS switch is set so that both speaker systems A and B are OFF, and then adjust the volume on the control amplifier. The POWER LEVEL METER can display output power levels up to 200 watts, with sensitivity adjustable via the METER RANGE knob for accurate readings at various power levels.
Proper maintenance and adherence to safety precautions are crucial for the longevity and safe operation of the Kenwood KM-991 amplifier. The manual dedicates a significant section to "IMPORTANT SAFEGUARDS" and "Safety precautions" to guide users.
One of the primary safety precautions is to prevent electric shock and fire. The amplifier should not be exposed to rain or moisture. The unit should be placed in a location that allows for proper ventilation, avoiding placement on soft surfaces like beds or rugs that might block ventilation openings. It should also be kept away from direct sunlight, heat sources, and excessive dust.
Power cords should be routed carefully to prevent tripping hazards and damage. If the cord is damaged, it should be replaced by qualified service personnel. The manual warns against inserting metallic objects or pins into the unit's openings, as this could lead to electric shock. In case of spills, the unit should be unplugged immediately and inspected by a professional.
For cleaning, users should avoid volatile solvents such as alcohol, paint thinner, gasoline, or benzene. Instead, a clean, dry cloth should be used. The manual also advises against using contact cleaners because they could cause a malfunction or deform plastic components.
Regular checks for abnormal smells or smoke are recommended. If detected, the power should be turned off immediately, and the unit should be serviced by a Kenwood dealer or nearest service center.
The manual also addresses potential issues related to carts and stands, advising against moving the unit with quick stops, excessive force, or uneven surfaces to prevent damage or overturn. Nonuse periods are also covered, recommending that the power cord be unplugged from the outlet if the unit will not be used for a long period.
Regarding outdoor antenna grounding, if an outside antenna is connected to the receiver, it should be grounded to provide some protection against voltage surges and built-up static charges, following the National Electrical Code (NEC) ANSI NFPA No. 70-1984.
The "In case of difficulty" section provides a troubleshooting guide for common problems. For example, if there is no sound or the indicator is off, the cause could be a poor connection at the wall outlet, an inactive power outlet, or protection circuitry operating. The suggested remedies include checking the outlet, ensuring the power switch is ON, and identifying and removing the cause before turning the power switch ON again. If sound is not output or indicator lights are off, potential causes include disconnected speaker cords, minimum volume setting, a switched-off speaker, short-circuited speaker cords, or short-circuited audio cords. Remedies involve connecting speaker cords properly, adjusting the volume, ensuring the speaker is on, and eliminating short circuits. If sound is not output from one of the speakers, the speaker cord might be disconnected, or the BALANCE control could be set to an extreme position. The remedies include connecting the speaker cord properly and adjusting the Left/Right balance.
Overall, the Kenwood KM-991 instruction manual provides comprehensive guidance for setting up, operating, and maintaining the stereo power amplifier, ensuring a safe and enjoyable audio experience.
General| Power output | 150 watts per channel into 8Ω (stereo) |
|---|---|
| Frequency response | 10Hz to 70kHz |
| Total harmonic distortion | 0.008% |
| Damping factor | 500 |
| Input sensitivity | 0.2mV (MC), 2.5mV (MM), 200mV (line) |
| Dimensions | 440 x 162 x 404mm |
| Weight | 16.7kg |
| Speaker load impedance | 4Ω to 16Ω |
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