Cabinets with horn-loaded tweeters often have an attenuator knob for controlling the tweeter. The drivers that produce the sound are referred to as tweeters, midranges, and woofers. Modern tweeters are typically different from older tweeters, which were usually small versions of woofers. The three different types of transducers are subwoofers, compression drivers, and tweeters. Modern mid-range speakers and high-range tweeters were placed throughout the room. High frequency tweeters, typically horn-loaded, are included in some bass instrument speaker cabinets. These tweeters have different directivity characteristics when compared to standard dome tweeters. Audiophiles felt that cone tweeters lacked the "airiness" of dome tweeters or other types. Hard dome tweeters are usually made of aluminium, aluminium-magnesium alloys, or titanium. In general, smaller dome tweeters provide wider dispersion of sound at the highest frequencies. Horn tweeters may have a somewhat 'different' sonic signature than simple dome tweeters. Celestion were the first manufacturers to fabricate dome tweeters out of a metal, copper. Most ribbon tweeters emit sound in a dipole pattern. The development of ribbon tweeters has more or less followed the development of ribbon microphones. However, the "sweet spot" created by the narrow dispersion of cone tweeters is small.