Full-range loudspeakers come in two primary types: two-way and three-way. What's a "way"? It refers to the method used by loudspeaker designers to maximize performance by dividing the frequency spectrum into sections.

In a two-way loudspeaker, low and high frequencies are split into sections, with the cabinet housing a large (8-inch to 15-inch) cone driver for lows and a compression driver loaded on a horn for highs. A three-way design offers an additional cone driver (generally 8-inch or 10-inch), often mounted on a horn, that is dedicated to the critical mid frequency section, where the vocal signal is reproduced (Approximately 300Hz to 3kHz.).

As a result, two-way loudspeakers are generally more compact, weigh less and cost less, while the additional mid-range section of three-way loudspeakers usually offers better vocal quality and intelligibility, and in general, greater overall output. In addition, three-way loudspeakers are usually larger, heavier and more expensive. The extra section often requires additional power amplification, an issue that relates both to system complexity and price.

One of the primary keys to a loudspeaker's performance, whether it be two-way or three-way, is the crossover. This divides and routes the signal to the appropriate components - low, high as well as mid in three-way designs. How the signal is divided, or perhaps more accurately, where in the spectrum the signal is divided by the crossover directly affects overall sound quality.

In a three-way loudspeaker, the crossover settings, or crossover "points," as they're called, should be above and below the vocal range, leaving it completely unobstructed. In a two-way loudspeaker, much care must be taken so that the crossover point between the two sections are seamlessly merged, so that there is no audible way to discern where one component picks up and the other leaves off. This is especially critical because the crossover point must reside somewhere in the vocal range; if the two sections aren't merged properly, intelligibility suffers.

The most common type of crossover is termed passive. Generally housed within the cabinet, passive crossovers are specifically designed and optimized for a particular loudspeaker, working with the amplified signal coming directly from the power amps. Active crossovers, on the other hand, are inserted into the system ahead of the power amplifiers. They allow custom crossover points to be established.

But because the signal division is occurring ahead of the amplification stage, use of an active crossover usually requires the addition of extra amplifier channels to power the loudspeaker.

Thus, a two-way loudspeaker with active crossover is termed "biamplified" (two amp channels), while a three-way with active crossover is "triamplified" (three amp channels).

Next time we’ll address matching power amplifiers to loudspeakers.

Keith Clark is editorial director of ProSoundWeb and can be reached at keith@prosoundweb.com