Free-standing or Box speakers

What do you envision when you hear the word "speaker"? I know some people think of a person on a podium addressing an audience, but for those of us in the audio and video realm, we think of something that generates sound - the final link in the process that starts with a microphone and enables sound to be captured, transmitted, and replayed.


And for most of us, that thing looks like a box.

We'll talk about other options (in-wall, in-ceiling, etc.) in another article. But right now, I'd like to talk about this most common type of audio speaker.

In previous articles, I talked about the different driver types (cones, domes, horns, ribbons, and others). The box is really just the enclosure that houses the driver and associated electronics.

However, that box is also an important element in the acoustical properties of the speaker. If the box is the wrong size, shape, or made of the wrong materials, it will affect the efficiency and the sound quality of the speaker.

For example, many speaker enclosures are made of MDF (medium-density fiberboard) covered with a lacquer or wood laminate. The lacquer or laminate is to help the box look good in your living room (MDF is not very pretty!). But the MDF is what really provides the acoustical properties.

The box itself serves as a resonance chamber and contains the sound emanating from the back of the speaker. This enclosure needs to be made of an acoustically inert substance to reduce "sympathetic vibrations" which can lead to the speaker "walking" across the floor, or even shaking itself apart! Lead or concrete would be excellent, except they're too heavy. MDF, on the other hand, provides a reasonable balance between weight and acoustical properties. Some manufacturers make their enclosures out of other materials as well. For example, high-end speaker manufacturer James Loudspeakers makes the enclosures out of aircraft aluminum, which has excellent audio qualities. But they still have to make a nice-looking outer shell.

The construction of the box is important, too. It needs to be completely sealed, or some of the sound will leak out of the enclosure instead of being sent in the direction of the listener. This keeps the sound from the back of the speaker from mingling with the sound from the front of the speaker. This is important because the speaker actually creates sound both when it moves forward and when it moves backward. The sound created by the backward motion is 180 degrees out of phase with the forward sound, which means if the two mingle, they will cancel each other out!

If you'd like to learn more about which speakers are right for your home theater or audio setup, please visit us online, or call us at 847.471.4420.