N.F. Chapman's description of the Film Dubbing Suite was made in 1950 only 6 months after it came into service. However, the growing needs of the expanding BBC Television Service necessitated changes and should be described here.
As at AP, two 35mm Ross film projectors and a 16mm Bell & Howell projector were installed. Again the RCA sound system was leased. A difference was that one recording room was used solely for magnetic recording and a separate room for recording optical negatives. The magnetic recording room was further equipped with an EMI BTR/1 15ips/30ips ¼" tape machine. This was used for replaying publishers' mood music tracks onto 35mm.
The sync system for this was simple. A 50Hz "hum" derived from the mains (which also fed the Selsyns) was mixed with the sound and recorded on the tape. For replay a 50Hz filter was inserted in the replay chain to suppress the hum, while at the same time the ampified hum signal was fed to servo circuits which controlled the film recorder. An adverse effect was that the recovered soundtrack was slightly deficient in bass, due to the 50Hz filter, though in practice this was not generally noticed since the narrator's voice had been recorded with an 80Hz high-pass filter to eliminate low-frequency thumps from the audio compressor, which was normally set to 8dB into 2dB (or "8 into 2").
The mixer room was equipped with a Marconi sound mixing console, and three TD/7 gram desks (giving a total of six turntables) for music and effects.
For a short time an experimental effects generator was also available. This was built inside the case of a small upright piano inside which were lengths of magnetic audio tape each connected to a particular key on the keyboard. The lengths of tape had been recorded with individual effects, such as a left footstep on one, and a right footstep on another. Thus by alternately "playing" the appropriate two keys footsteps could be synced "live" to picture. Regrettably I have forgotten the name of this apparatus, except that I believe it began with an "M" and Eric Robinson had some connection with its development.
CNR (Children's Newsreel) and later TNR were dubbed here, as were many other programmes, such as Panorama. The Dubbing Theatre auditorium was at times used to record "talking head" interviews.
Plan of Dubbing Projection rooms
By this time it had become apparent that the two separate sound film reproducers installed in the Review Theatre were not needed there, and so had been re-installed in the dubbing projection room. The existing pair were designated D and E, with the extra pair F and G. The 35mm projectors were A and B, with the 16mm being C.
An additional preview theatre was needed so the large room at the end of the corridor, next to the scenery lift, was converted (in 1953 it had housed the CBC "Hot Kine" telerecording system). Inside this room was a metal projection room with two Bell & Howell projectors, modified for "double-headed" showing of separate magnetic track, though this facility was not used (except occasionally by me...!). The theatre was designated Theatre B, the original Review Theatre in the Film Dubbing Suite now being called Theatre A.
With the revising of news' "no additional sound to be used" policy, a need for additional recording facilities became evident. Behind the Dubbing Theatre's mixer and recording rooms was the old Artists' Green Room, no longer used, and in the later 1950s this was converted into twin Transfer Suites, one for film recording, the other for non-sync sound recording, the latter replacing cramped facilities in one of the former dressing-rooms upstairs. At the same time a Westrex 16mm magnetic film recorder was installed in the dubbing recording room in addition to the 35mm RCA set-up.
Film Transfer Suite
The BAF film recorders had interchangeable head blocks and on 16mm this facility was widely employed. Thus various track widths and positions could be used - the standard 100mil edge track, a 200mil edge track and a 200mil centre track (the preferred standard for sepmag recordings).
The 35mm magnetic recorder was modified in 1959 with the additional facility of manual speed adjustment for use in the Cablefilm system.
The Transfer Suite was linked to the Dubbing recording room via a shared darkroom.
Plan of Film Transfer Suite
(drawn from memory)
The monitoring loudspeaker unit was a BBC design LSU/10 which used a Parmeko loudspeaker with a Lorenz HF "tweeter" to extend the upper frequency response. However the unit installed in preview Theatre B, just along the corridor, gave much better quality, so one day I surreptitiously swopped them. No one ever noticed....
Each of the recording rooms had a bulk eraser for the wiping of magnetic film, as film recorders were not fitted with an erase head. One had to exercise care when wiping a roll of film, as it was all too easy to leave a low-frequency "thump" if the roll was not removed from the strong erasing field slowly. The BAF bulk eraser was marginally superior to the RCA one.
An interesting point arose soon after the AP Transfer Suite came into operation. A colleague of mine who had just joined Granada Television in London, helping to select and order equipment for Granada's tv studios which were being built in Manchester at that time, was surprised at the sound quality obtained from our BAF 16mm sepmag recorder.
Since the 35mm recorders were equalised up to around 10kHz, with 16mm running at 2/3rds the speed (ie 7.5ips as against 18.5ips), he had assumed that the 16mm quality would have been reduced accordingly. However, 10kHz was easily obtainable on 16mm magnetic and he had not realised that the 35mm systems were not required to operate at their theoretical maximum top frequency. Thus recordings made on either gauge would nominally sound the same.
And so Granada Television felt able to go ahead and purchase 16mm magnetic film equipment - on our recommendation, so it seemed!
Among the many jobs I had to do in those years, one stands out. It should have been simple but proved most awkward. To improve the general standard of television sound for music programmes, Glyn Alkin had devised a filmed lecture for studio staff. It was done "on the cheap" using, instead of shots of an orchestra, pictures from an LP sleeve to illustrate orchestral instruments heard on the soundtrack.
Being 1 hour long on 16mm this was 2,400ft on one large spool. The requirement was to record onto several striped 16mm prints. In those days the equipment could not run back in sync, so if something went wrong, such as a drop-out, the recording would have to be started again from the beginning.
And indeed drop-outs did occur, rather near the end....
What's in a name?
The main equipment consisted of two dual-speed (33S!/78rpm) Presto disc recording channels, a TD/7 78rpm disc reproducer, a DRD/5 3-speed microgroove player, and a BTR/2 ¼" tape recorder, plus a Ferrograph ½-track machine, and of course the LSU/10 loudspeaker.
(with John Duncan)
In the above picture the two Presto units are at the back. The DRD/5 is at extreme lower right with the TD/7 immediately behind.
Looking through the window from the Film Transfer Suite. The BTR/2 is in front, with its cover open. At extreme left is the LSU/10.
Dubbing Theatre refurbishment
While all this was going on, work had to continue, so a temporary "lash-up" was setup in the theatre itself. A "portable" narrator's booth was installed near the back, with the mixing "console" on a desk in front. This actually consisted of Outside Broadcast equipment, such as the OBA/8 mixer etc.
On the extreme left is the narrator's booth, the window into the mixer room is just visible on its right. In front on the table is the mixing unit, while the telephone is standing on the talkback unit. Behind that is an apparatus bay made of Dexion, and behind that is the fx disc library. A large bundle of cables connected all this to the recording and projection rooms.
After the new installation in the mixer room was completed, tested and handed over, the theatre was cleared and put back to normal. The AP Dubbing Theatre remained in operation until News moved out of AP to the Television Centre spur, and throughout the Open University period until they, in turn, moved to their new studio complex in Milton Keynes.
And so ended a chapter in BBC Television history.