530 Recording Studio Design would be needed for high level radiation (110 dB SPL +) of signals in the 500 Hz region. Because of the off-axis phase cancellation for 8 cm wave- lengths being generated by 20 cm diameter cone, the directivity would tend to become too narrow for studio use. There are therefore problems in covering the whole mid frequency range with a suitable drive unit for high level, high quality monitoring, although the horn-loaded Kinoshitas go from about 500 Hz to 20 kHz with a single, though phenomenally expensive, compression- driver/horn combination. (See Figure 20.1(a).) 20.8.5.1 Cone drivers Cones and domes are both used in domestic high fidelity loudspeakers covering the entire mid-range, but such small units can rarely be capable of dissipating the waste heat in high-level systems. Cones have always been a popular choice for mid-range drivers, and they have the rather fortunate tendency to break up in such a way that the higher frequencies are often decoupled from the outer edges of the cone, and thus tend to radiate from the smaller diameter central section. They can thus maintain their wide directivity as the frequency rises. Figure 20.11 shows two small mid-range cone drivers covering the mid frequency range in a high power monitor system, but here they have been fit- ted with `noses' and mounted in a shallow waveguide. The combination of the nose and waveguide lead to what is really a form of horn loading, which helps to augment the sensitivity of the system and also helps to control the directivity, both of which are desirable assets. Such a system of mounting