design principle or cost, has a completely flat frequency response; all speakers color the sound to some degree. Monitor speakers are assumed to be as free as possible from coloration. While no rigid distinction exists between consumer speakers and studio monitors, manufacturers more and more accent the difference in their marketing material. Generally, studio monitors are physically robust, to cope with the high volumes and physical knocks that may happen in the studio, and are used for listening at shorter distances (e.g., near field) than hi-fi speakers, though nothing precludes them from being used in a home-sized environment. In one prominent recording magazine, Sound on Sound, the number of self-amplified (active) studio monitor reviews significantly outweighs the number of passive monitor reviews over the past two decades indicating that studio monitors are predominantly self-amplified, although not exclusively so. Hi-fi speakers usually require external amplification. Monitors are used by almost all professional producers and audio engineers. The claimed advantage of studio monitors is that the production translates better to other sound systems. In the 1970s, the JBL 4311's domestic equivalent, the L-100, was used in a large number of homes, while the Yamaha NS-10 served both domestically and professionally during the 1980s. Despite not being a "commercial product" at the outset, the BBC licensed production of the LS3/5A monitor, which it used internally. It was commercially successful in its twenty-something-year life, from 1975 until approximately 1998. The diminutive BBC speaker has amassed an "enthusiastic, focused, and ... loyal following", according to Paul Seydor in The Absolute Sound. Estimates of their sales differ, but are generally in the 100,000 pairs ballpark. Professional audio companies such as Genelec, Neumann (formerly Klein + Hummel), Quested, and M & K sell almost exclusively to recording studios and record producers, who comprise key players in the professional monitor market. Most of the consumer audio manufacturers confine themselves to supplying speakers for home hi-fi systems. Companies that straddle both worlds, like Amphion Loudspeakers, ADAM, Dynaudio, Focal/JM Labs, JBL, PMC, surrounTec and Tannoy tend to clearly differentiate their monitor and hi-fi lines. See also Loudspeaker acoustics List of loudspeaker manufacturers Digital room correction Room acoustics References Audio engineering Loudspeakers