Dialogue for each episode is prerecorded, and either at AP Film's own studios or at The Gate Recording Theatre the recording is edited to remove pauses, particularly where an artist is playing two characters in one scene. Retakes and wild tracks are cut in, and the episode is brought down to a suitable length for filming. It is now on one 1" master sound tape.
In the AP Films studios, a special dupe of this tape is played back during filming, and through a resistance-capacity network pulses are also taken off the tape to operate solenoids in the head of each main puppet figure, thus controlling the jaw and lip mechanism. Thus lips move in perfect sync with recorded sound.
That was the essence of the system when Gerry Anderson first devised it for use in the ATV Supercar series. Others had attempted lip-sync along different lines, with only fair success, because there are electronic difficulties in getting realism. Anderson and his technical team sought the aid of two Midlands concerns, long-experienced in recording and electronic work. Technical help was given by R.T.C. Wright & Co Ltd, of Perry Barr, and the Hollick & Taylor Recording Co Ltd, of Handsworth Wood, Birmingham. Hollick's built the prototype of a control system to Gerry Anderson's main theme, and Roland Wright's group gave invaluable aid in subsequent lip-sync development.
As now perfected for Thunderbirds, the control dupe tape is played back in the studios on modified EMI TR90's, the circuitry being completed through what Gerry Anderson irreverently terms a 'natterer,' since it takes pulses off the tape, acts as an electronic relay, and provides varying currents to operate the solenoids in puppets' heads. Each replay head winding is connected to a network with diodes operating relays putting a 50-volt DC supply on to parallel copper wires running along the puppeteers' gantry.
Usually up to four figures can be made to 'natter' at once, off the same tape. AP Films' electronic team has experimented with automatic control tracks to pinpoint each individual figure. They have also used ultrasonic switching with some success. On Thunderbirds it has been found most practical to route the correct 'natter' pulses to the appropriate character in camera by means of four quick-action switches on the lip-sync console. A development through the years has been a retention scheme, which has changed the whole artistic effect of lip-sync.
It will be obvious that taking pulses from a tape does not automatically indicate duration of sound, but only intensity. A pulse will operate the diode relay and open the puppet's lips via the solenoid. However, realism (especially in close-up) depends on keeping the mouth open for long vowel sounds, and but briefly for staccato sounds.
There is also a third resistance-capacity network fed off the tape's sensitivity level, so the lower-jaw solenoid is opened just a little way for the 'narrow' sounds such as 'he' and 'me,' and much wider for the open, long-sustained vowels like 'oh,' and 'ah.'
Along the gantry run the parellel bare copper wires, four wires and a neutral, from which the speech wires to the puppets are linked. At present the eyes are hand-controlled, although a separate electronic network is available when needed for eye effects. In earlier AP Films series the eyes were painted wooden pellets, but now colour has come it is essential to use genuine artificial eyes of the type designed for human use. The sole difference is that for human optics only a shell is required, whereas with puppets the complete sphere has to be fitted. A minute tracker rod inside each head moves the eyes in parallel. Some characters have a further remote control for up-and-down movement of the eye ('blinkers' in Supermarionation jargon), while the electronic action (not used, in fact, in Thunderbirds) has a speed control for 'flick,' 'blink' and 'slow-sleep.'
Behind each 'natterer console' is a modified TR90. While EMI have produced other, more ambitious tape decks, the rugged 90 is ideal for lip-sync, for a heavy-duty synchronous hysteresis drive motor is directly coupled to the capstan assembly, speed control is by a single control switching poles of the motor, and at the same time automatically adjusting all preset gain controls, and changing the equaliser network. Spooling is by separate motors controlled by solenoid-operated servo brakes, and are switched off at the end of the tape by an arm coupled to a microswitch.
The mechanical unit also carries the replay pre-amplifier and oscillator, and is provided with a bias-and-erase push-pull oscillator operating at 100 Kc/s. Plug-in equaliser units are switched by relays operated by the speed switch on the tape deck. Not all the facilities in the TR90 are needed for lip-sync. The lip-sync console itself carries four tone controls and four separate gain controls to regulate DC pulses to each puppet. Power pack of the TR90 contains a 24 volt DC supply for the solenoids, and auto-transformers for connecting mains supply to the spool motors, together with pre-set hum balance controls. Lip-sync work is a hard chore at AP Films, however, the TR90 heads have beryllium-copper gap spacers of 0.00025" and are potted in Araldite D epoxy resin. The Ferrox-cube core erase head has a 0.02" PTFE gap spacer.
Two TR90's are used to record all the characters' voices, and when transfer is made to 35mm film another pair of TR90's is used to maintain quality and avoid any variation in the soundtrack.
"These EMI machines," I was told, "are used from 8.30am until 10pm six days a week and are heavily used, yet in spite of this they require less attention than almost any other equipment used."
Originally all lip-sync equipment was housed in a booth behind a soundproof screen overlooking the main stages. But in time for the start of Thunderbirds it was decided to move each 'natterer' out to the floor. While live television is produced in a studio with a remote producer's gallery (CCTV being in some studios the only link between the artists and Big Brother), it was felt that Thunderbirds needed a technique similar to that in film studios, where the director himself is always out on the floor, close to the cameras.
Big Brother is looking at each scene of Thunderbirds in the making, however. Every VIP office, including those of Gerry and Sylvia Anderson, and technical director Reg Hill, has a Pye 2816 monitor which at the touch of a button on a control box can be linked to any camera on the floor.
This is an invaluable time-saver. A producer or a technician in the middle of a production has no need to stop work to hold a conference with an executive. Nor does a busy VIP need to go to each of the four stages in turn to discuss production procedure. For example, if a producer wants to consult Gerry Anderson while a shot is actually being prepared, he can switch on the intercom... "This reverse-angle shooting along the road – scene 143, Gerry – I'd like your advice about Thunderbird 2 moving from its hangar. Special Effects have given me a line of palm trees which fold back so they don't foul the wings as it taxis to the launching ramp. Is this the effect you wanted?" Without moving from his desk – or perhaps even while working on another stage – Anderson can see on his CCTV monitor the actual shot as the Arriflex sees it.
Coupled to each camera is an all-transistor Pye Lynx camera, the latest TVC/1A, switched to 625 lines random interlace. When CCTV monitoring was first used by AP Films, the Pye Mk IV camera was used, and the monitor feed was RF. Now the Lynx is found to be more suitable with a wider network, and the output is video. Puppet operation being by DC pulses, there is no mutual interference with CCTV. Staticon C938 tubes are used in these cameras, which are coupled directly to R35 or Arriflex. Only feed to the self-contained camera is a 240 volt AC mains feed, power consumption being approximately 13 watts per camera. The video output is 1.4 volts peak-to-peak (peak white positive) on 75 ohms. Spectral response is similar to panchromatic film, and there is a high video quality with a horizontal resolution of not less than 450 lines. The 2816 monitor is portable, and sensibly has the chassis isolated from the AC power supply by a tapped-primary transformer. There is a 14" rectangular aluminised tube, and the monitor has an integral loudspeaker and soundchannel. Incoming video signals are applied to a frequency-compensated wide-bandwidth video amplifier.
When watching Thunderbirds episodes in production I have had the curious feeling that the scene on the Pye monitors is at times even more brilliant than in the studio itself. This is due to the aluminium-backed fluorescent screen used with the electrostatically-focused tube. The thin, bright metal backing for the tube phosphors permits easy transit of high-velocity electrons, and by reflecting light from the phosphor layer produces a very brilliant image.
Larger monitors are used in the studio, there being three on each stage. Near the top of the puppeteers' gantry is a brilliant 23" monitor switched to scan reversal. Reason for this trick is interesting. In the old theatrical days, puppeteers could see actions only in a mirror, so they soon became accustomed to piloting themselves from reversed action. By scan reversal on the CCTV monitors, they get a mirror effect.
"Use of CCTV monitoring has proved essential," I was told by Reg Hill. "Advantages to the director and lighting-cameraman are obvious. The lighting-cameraman can see what part of the set is being shot without needing to get down and monopolise the viewfinder. (On small stages our cameras have to be placed inconveniently low, anyway). Further, he can light without the need to look through the camera. Apart from mirror work, the puppeteers can see only the tops of characters' heads, but for CCTV. Now the eye movements are so important, viewing on a 23" monitor helps to produce a sympathetic and artistic result. Yes, Supermarionation is pretty largely an electronic process..."
Will the next series be produced with fully automatic puppets, like robots? This idea captivated the AP Films technical team some years ago. They worked on it, produced several versions of completely automatic-controlled stringless puppets. But they were not used in Thunderbirds (though several scenes do show Robots, which in fact are normal stringed puppets) since it has been found the remote-controlled robot is too stilted.
"We do need the human interpretation of the puppeteer to produce realistic action," they say. So even this 2,000 AD saga can never be all-electronic.