It became clear that the brand new lower profile Mark 3 desk would now be limited to four "mixer" studios requiring a TO position to handle outside sources. After much anguish it was decided to stick with a proven design and make the Mark 3 as a mixer version of the Mark 4. Apart from the cost implications, one of the most telling reasons for sticking with the same design was that, at that time, most SMs worked across a wide range of studios. The number of controls had greatly increased, compared to Type B and at the same time radio had speeded up, so to be able to grab the same control in the same place in different studios was a great advantage.
3B was one of two Mark 3A desks with 24 channels - 10 local, 2 dedicated phone channels and 10 outside sources. The other Mk 3A later went into 4A. There were two Mark 3 desks with 32 channels (20 outside sources) in B9 and 4C. Apart from the ability to transfer the SMs outside talkback working to a headset, there were few changes from the Mark 4.
The Technical Operators position is on the left with outside source selection and cue modules. For everyday use when this position was not staffed, 4 of the cue modules are duplicated to the right of the faders. Here too are cue modules for the dedicated telephone channels and a switch-down panel to select telephone balance units. Note that the "Tone to Clean Feed" buttons have now gone.
The studio was in the location of the original H30 and on the opposite side of the cubicle in the space occupied by the original 3B studio was 3K. This was designed as a back up/preparation studio to 3B and had a 12 channel GP desk with access to all 3B's outside sources without reference to control room. Originally it was designed for one SM operation with tape machines either side of the desk. This required a different method of working from anywhere else and was not a success. 3K was quickly changed to the conventional arrangement.
The large box on the wall is a Tape Control Panel. This is an elaborate way of routing all repro sources to a number of bus bars or individually in mono or stereo. Another panel out of shot carries record input selectors.
