Matching an 8 Ohm Speaker

Speakers with an impedance of 8 ohms are very commonly used in home audio or other domestic setups. They come in all shapes and sizes, and a look though the 8 ohm speaker listings in eBay will show you just how diverse the range is. From small and inconspicuous ceiling speakers, to large, in-your-face, DJ woofers, you'll find them all on eBay.

Why is impedance matching important?

Impedance is a measure of how much the speaker resists the audio signal of the amplifier. Most amplifiers in the home audio market are designed to output their audio signal to 8 ohm loudspeakers, and correctly matching the impedance of the speakers with the required output of the amplifier ensures the most efficient transfer of the audio signal to the speaker. In other words, if the amplifier of your music system specifies an 8 ohm output, an 8 ohm speaker will match the impedance perfectly and provide the best results.

Can 8 ohm speakers be used with 4 ohm output amplifiers?

Yes, they can, but the power output to the speaker will be lower because of the higher impedance. Just turn up the volume. On the other hand, using a 4 ohm speaker with an amplifier that specifies an 8 ohm speaker output isn't recommended. The speaker will draw more than the optimal amount of current from the amplifier due to the lower impedance, which could have a harmful effect on the amplifier. If the amplifier requires an 8 ohm speaker, then that's what you should use.

What kinds of home audio speakers commonly have 8 ohms impedance?

A speaker impedance of 8 ohms is so common that virtually all home audio speaker types have 8 ohm versions. These speaker types include:

  • Bookshelf speakers: Compact enough to fit on a bookshelf, most bookshelf speakers have an impedance of 8 ohms.
  • Tower speakers: These floor-standing speaker cabinets contain several vertically arranged speakers. If a tower speaker is labelled as an 8 ohm speaker, then whatever the impedance of each individual speaker within the cabinet, the total impedance will be 8 ohms.
  • Subwoofers: Designed to enhance low-frequency audio signals, many of these are 8 ohm speakers.
  • Wireless speakers: Many wireless speakers have an impedance of 8 ohms, but as they have a built-in speaker amplifier, the impedance matching is taken care of.