A low-frequency loudspeaker. A hi-fi speaker cabinet typically contains a low-frequency bass speaker (woofer), a mid-frequency midrange speaker and a high-frequency treble speaker (the tweeter). In a two-way system, only woofers and tweeters are used. However, there are countless high-fidelity loudspeaker configurations on the market, many with more than one speaker of the same type within the enclosure. See subwoofer.