Chapter 23 A mobile control room The acoustic characteristics of a vehicle body. The problems presented and their means of control. Loudspeaker design for specialised conditions. It would seem appropriate in at least one chapter to try to go through an entire design process. This way it will be possible to get an idea of the typical problems that arise, and the means available to solve them. Furthermore, if a mobile recording vehicle is chosen as the object of the exercise, it will allow us to look at another set of circumstances that have not been discussed in earlier chapters. So, let us now look at the concept, design and construction of a multitrack mobile recording vehicle, designed by the author at the end of the twentieth century. 23.1 The problems to be solved During the spring and summer of 1998, Portugal was presenting Expo '98, a world fair of the oceans. The enormity of this exercise was to occupy much of the country's mobile recording and broadcast facilities, so the company Banzai Lda, which was engaged in many other recordings, decided to invest in a mobile sound recording vehicle in order to fulfil their own recording contracts. The final decision to build a vehicle was only taken in early 1998, and the first recordings were to begin at the start of the following May. The three months available for the design and construction appeared to be too short to make an entirely new truck, so a search was made to find an existing vehicle that could be re-built to their specifications. They discovered that NOV, the Dutch broadcasting organisation, had a sound vehicle for sale, so one of Banzai's owners went to Holland to see it. The truck appeared to be suitable for their needs, and it had the necessary infrastructure, but internally it needed to be totally rebuilt. This was quite an interesting challenge, because the request came exactly at a time when 25 years earlier, the selfsame designer had been building the first of the Manor Mobiles, to which the construction and dimensions of the NOV truck were not too dissimilar. The problems were therefore known inti- mately, and it was a great opportunity to see if it would now be possible to deal with the limitations that had been so seemingly insoluble in the past.