Recording the Proms in 5.1

Classic Sound’s mix suite is permanently installed for 5.1 surround mixing. It includes an AMS Neve Logic 2 digital mixing console with Lexicon 480 and a TC Electronic 6000.

This year, the BBC conducted a series of experimental productions with Wembley-based specialist recording company Classic Sound. The result? The Last Night of the Promenade Concerts (Proms) in high-definition and 5.1 surround sound.

BBC Special Projects first approached Neil Hutchinson and Jonathan Stokes of Classic Sound in 2003 to look into the viability of producing a live 5.1 mix of the Last Night of the Proms at The Royal Albert Hall (RAH) for broadcast. To a degree, it was successful, although it was difficult to monitor stereo and 5.1 live mixes at the same time. In the end, Hutchinson and Stokes felt that, if nothing else, they had produced a TASCAM tape of the 5.1 mix and gained some experience. They didn't expect anything more would come of it.

Thus, when the opportunity arose to record this year's event for BBC Worldwide, Hutchinson and Stokes felt that the experience they gained last year would aid them in this new project. This year, it was a different project for a different end client. The project was driven by the HD picture element. And, of course, 5.1 surround goes hand-in-hand with high-definition television.

Recent developments in HDTV broadcasting in the USA and other countries have prompted the BBC to investigate opportunities for export. Kevin O'Neill, operations coordinator for BBC Worldwide International Television, explained that the BBC's interest in opportunities in the USA had come from the specialist channel Discovery HD Theatre. The U.S. company has been broadcasting last year's Proms and some more recent high-quality BBC music recordings. These recordings feature 5.1 mixes produced by BBC senior sound supervisor Andy Payne and Classic Sound over recent months, originally for DVD recordings. O'Neill said that the current recordings seem to be going well and, barring any unforeseen circumstances, the BBC will be taking this year's recording. The deal is for HDTV recordings in 5.1 surround, which is not viewable yet in the UK but is gaining popularity in the USA and other countries.

Hutchinson said that the difference between a TV recording of the Proms and the radio broadcast setup is that BBC TV only goes to the Proms for one or two shows, whereas radio takes in the whole series. Traditionally, television uses the microphone setup from the radio broadcasts. Thanks to last years' experiments, Classic Sound had a good idea of where to put the extra mics to create the 5.1 elements.

Payne was in charge of the setup and described some of the issues involved. The radio broadcast arranges around 80 to 100 potential microphone sources, which is a huge rig, although they are not all used at once. Assuming the recordists would be taking about 70 sources at once, it makes it impractical to dupe all that for a 5.1 mix. The solution last year was to generate 5.1 stems, which was only partially successful because the RAH is not a good monitoring environment. The Proms are also unusual because the RAH is circular. There are people singing behind you and to the side; the sound seems to come from everywhere.

This year, the team did a little extra. It adapted the radio rig plus a pair of B&K omnis above the conductor's head to get a little closer. Further back, for an overall cover, it placed a stereo pair of cardioid Schoeps MK 4s to give them surround coverage for the penultimate and last night Prom. The team also added another pair of MK 4s facing backwards at the same height as the main pair and about 6m away. This resulted in a wide and even spread of coverage of the arena (the circular standing area in front of the stage) and kept things simple. The other element it used in the mix comprised three B&K omnis in the mushrooms of the roof of the RAH to add a more diffused sound.

Payne and Hutchinson explained that the microphones have to be time-aligned in the RAH, or else you would hear a slap effect as the sound from, say, a choir, arrives at the spot mic before the surround mics some distance further back. Some inherent delay in the sound is desirable to give a sense of space, but too much is not good. This is especially true for surround when the listener is in the middle, whereas stereo requires that sense of space.

Everything at the RAH was recorded to 64 tracks of Pyramix plus some effects and presenter mics on TASCAM DA88, all later edited to conform to the picture edit. The HD visual also has a picture delay that the team had to take into account. With microphone time-align delays as well, the mix was to become quite intricate.

There were extra complications on the last night. The orchestra was playing the Sea Songs while live cutaways took in choirs in Birmingham, Edinburgh, Dublin and Swansea. The soundtrack was transmitted from the RAH to a satellite link and back down to the region where a choir might be singing along, then back by satellite again to the RAH. The audience could not hear it in the RAH, of course; it was only audible on the broadcast.

Payne said that the orchestra in the hall is the accompanying music for all the songs being sung in each region. They were recorded onto DA88 in stereo pairs: a clean choir in stereo and a clean audience on another stereo. The BBC's requirement was for two mixes: a full mix featuring presenter Alan Titchmarsh and a music-and-effects (M&E) mix for non — English-speaking audiences.

Payne said that to make the 5.1 mix, he had the 64 tracks on Pyramix from the RAH and eight tracks of DA88 in 16 bit from each region, which he then put onto TASCAM MX-2424 for convenience. One of the problems was the difference in acoustics between the orchestra in the RAH, and, say a choir outdoors in Swansea. He added a bit of artificial acoustic from the RAH to help the transition. In the end, he didn't use the audience from the regions because it made things more confusing.

Basically, there were two programs: the penultimate night performance including the Shostakovich Symphony #5 and The Last Night. The first has an emphasis on the music and what is being played on the stage, whereas the second is a big event and you can go for a huge surround effect. Camera coverage reflects that as well. The Last Night covers audience activity, the presenter and all the crowd activity as well as the musicians.

Payne used quite a few 5.1 orchestral and presentation stems and VCA groups. The relevant bits were assembled, mixed and finished into the two versions, the main mix and an M&E mix. The mixes were recorded onto 16 tracks of DA98, which contained the necessary broadcast stereo mix as well as the 5.1. Payne said it was interesting trying to place the presenter. When Titchmarsh was in view, he sounded correct at center front. But when he was not in view, it sounded better with him being central, next to the listener.

Classic Sound produced the mix on its AMS Neve Logic 2 digital mixing console with Lexicon 480 and a TC Electronic 6000 for reverb and the dynamics on the final six channels. Once the mix was complete, Hutchinson's suggestion of using Dolby E as the encoder turned out to be successful, making the delivery easier and more flexible.

Chris Hook is a technical journalist based in the UK.