Verdi Requiem with London Symphony Orchestra Apr 07 by Neil Hutchinson in Producer's Notes, Recording Reports

Recording a piece like the Verdi Requiem in The Barbican presents various technical challenges. Scored for very large forces it pushes to the limit the number of people you can fit on the Barbican Stage.

It’s a piece with an enormous dynamic range. Maestro Noseda, with this performance, teases every dB of Dynamic from barely audible to ear splitting. Representing that in a recording is a real challenge, particularly in an acoustic like the Barbican, which has a relatively short decay time and a lot of very early reflections which can make things a bit confused and confined sounding, particularly at louder dynamics. We have found that a purist minimal single point mic approach doesn’t really give you the chance to iron out some of the issues with the hall, particularly with the larger Repertoire like this. Similarly using many microphones, in a multi-mic approach doesn’t help either as we find that using many of mics just pulls in lots of early reflections adding to the confusion. Our approach, refined over several years now, is to work with the Barbican acoustics and attempt to capture an accurate sound whilst having enough control to correct any unwelcome side effects of having such large forces in such a relatively confined space.

To that end, we use as our main mic array, a Decca tree of three Schoeps Mk2s microphones, plus a left and right wide omni of Neumann M50 microphones. This together with two rear space mics – Schoeps Mk21 – forms the basis of the LSO live sound in both stereo and 5.1 To this we add a few stage mics such as two, or sometimes three Woodwind mics, Horns, Brass, Timps, plus in the case of the Verdi: 4 x soloist mics. The 4x Chorus mics (except for the soloist mics) tend to be quite general, positioned to capture zones of sound rather than just one or two instruments.

Recording the LSO in DSD

All LSO Live recordings are captured as DSD audio files on two parallel Pyramix 10 workstations. Currently we record one microphone per track in DSD128fs format. Our intention is to move to DSD256 fs as soon as we feel confident that the technology is completely solid. LSO live recordings are based around live performances. Therefore we cannot afford for the recording system to fail as it’s a bit difficult to go back and repeat a concert!

The main microphones are suspended from the roof over the Barbican stage. As these 7 microphones contribute around 75% of the sound, we have a Merging HAPI interface installed in the roof to keep the cables between microphone and Mic amp as short as possible. The HAPI as well as containing remote mic amps, also contains the AD convertors. This is connected onto a Ravenna Audio Network via a combination of fibre and Cat6 cable. Onto the same network is connected more Merging Horus units to deal with stage based microphones, plus the control room loudspeaker and headphone monitoring. Using a networked audio solution allows us to connect multiple sources and destinations and expand the system to suit the repertoire.

Using a double Merging Pyramix system

Ordinarily we record all the audio on two identical workstations running Pyramix V10 software. The audio is recorded onto SATA drives, although we are keeping a careful eye on the costs of SSD’s. However, with a project such as the Verdi requiring at least 2Tb of storage per system this is not yet a cost-effective solution. As already stated- LSO live recordings are based around live performances, however there are often two performances, and together with recording rehearsal material this gives us the flexibility to correct any mistakes and edit around any problems. Although all the editing happens in the multitrack domain, we also record all our session mix automation with the audio. This data is edited alongside the audio, which means that once the edit is complete we have the same mix as on the sessions, but retain the ability to tweak things if required.

Our Philosophy has always been to get as much right on the concerts, however it is always nice to be able to refine things afterwards if required. Once a final stereo and 5.1 mix has been finalised, the audio then goes through a de noising stage where we will try and remove as many extraneous disturbing noises as possible, using a clever bit of software by Cedar audio called ‘retouch’. All this manipulation is undertaken at the highest resolution currently available, and the resultant DSD and PCM masters are derived as down conversions from the master project.

Neil Hutchinson

Member of the team of recording engineers for LSO

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