550 Recording Studio Design other rooms and on other systems are to be minimised. Moreover, only in rooms with well-controlled acoustics can the five full-range channel option be heard to be superior to the single (or double) sub-woofer option. In rooms with less ideal low frequency control, the single sub-woofer option can reduce the variability of a sound as it is routed to different locations (which at low frequencies would tend to drive different modes to different degrees). Whether such poorly controlled rooms should be in use for serious surround mixing is a moot point, but the fact is that many of them are used for such purposes. It should also be added, here, that attempting to mix on a sub- woofer/satellite system using bass-management can be very risky. These sys- tems can often be so far from the reality of what is on the recording medium that they could hardly be considered to be `monitoring' anything other than their own ideosyncratic sound. 21.8.2 Processed multiple sub-woofers Some of the larger manufacturers of professional monitoring loudspeakers have accepted the fact that there is now a tendency for many people to mix all forms of music recordings in rooms with little acoustic treatment, especially at low frequencies where treatment can be both expensive and space consuming. Companies such as JBL and Genelec have put much effort into the design of low frequency loudspeaker systems which are intended to deal with room prob- lems in such a way that, whilst not reaching the standards that can be achieved in well-controlled rooms, they certainly improve the conditions of monitoring