Harmon Kardon audio components have a history of high regard in the home audio field dating back to the mid-1950s. Today the company markets a range of audio equipment, including speakers for home stereos, home theaters and computer systems. Since the company makes both active and passive speakers, there are a variety of things to check when your sound fails.

Checking Connections

Harmon Kardon speakers use a variety of connections for speaker cables. Bare wires, RCA jacks and 1/8-inch audio plugs are the most common. If sound loss is intermittent, or failing in only one speaker, a loose connection is likely the culprit. Usually this can be corrected by removing the speaker wire and reconnecting it, regardless of connector type. If the problem persists, it may indicate a problem with the connecting cable or elsewhere in your audio chain.

Checking Speakers With Other Components

If the sound suddenly cuts out from all speakers in your system, it's not as likely that the culprit is a bad connection. You may be able to verify that your Harmon Kardon speakers are working by connecting them to another sound source with the same connection type. For example, Harmon Kardon computer speakers use a 1/8-inch stereo phono plug to connect to your sound card. A personal MP3 player also uses this type of connector, so if your speakers work fine with another source, look to the original sound source as the problem.

Active Speakers

Harmon Kardon markets speakers with matching amplifiers built in to the speaker or subwoofer enclosure. Active speakers require power for the amplifiers, so this type of speaker will have a power cable. Frequently, removable power cables can work away from terminal contacts without physically disconnecting from the speaker. Press the cable firmly into the speaker or subwoofer to ensure connection. Check the connection at the wall plug, and check that the power switch is on and any indicator light is on. If power connections are checked but indicators don't light up, your speakers may require service.

Passive Speakers

Harmon Kardon components are collectibles among audiophiles; older speakers, well cared for, still sound good today. Older speaker design often uses bare wire and post terminals to connect speakers to amplifiers. Over time, oxides can build up on both the posts and speaker wire. While reconnecting usually addresses this, speaker posts can benefit from cleaning. Using a pencil eraser or light steel wool to polish up the metal parts of the speaker post removes oxides which interfere with reliable connections.