Professional Sound - August 2017 - Page 32

32 • PROFESSIONAL SOUND original stage costumes, documents of the time, Keith Moon’s drum set, and footage from Michael Wadleigh’s classic concert film displayed on a giant curved screen that dom- inates the room. That video is accompanied by an immersive AMBEO 14.1 audio system created by Sennheiser for this exhibition. This is the first exhibition to use the 14.1 system, which builds on the 9.1 immersive system used in the David Bowie Is exhibition. Of course, the original audio from Woodstock was not recorded in 14.1, so turn- ing it into an immersive experience required some audio trickery. “Basically, the AMBEO 3D technology is a recording and playback technology,” says Germany-based Gregor Zielinsky, the senior manager of research and innovation at Sennheiser, who created the 14.1 mix for the Woodstock room. “Together with the recording technology, we also de- veloped a system to upmix stereo to 3D. Now this is a trick, of course; it cannot be perfect and cannot be as perfect as a real 3D record- ing, but the necessity is evident because if you had a kind of 3D system at home or in your car, for example, and you have all your stereo materials – be it from CD, MP3, even vinyl, or coming out of the radio or TV – you want to make use of your 3D system. So we developed a system that evidently works pretty well because it has been used already in the David Bowie exhibition and others.” Using the 9.1 AMBEO system on the David Bowie Is exhibition, Zielinsky says they learned a lot about playing back 3D audio in large rooms. “Usually, you play it back in studio-like rooms,” he says, “and that is why we have modified it this time in the Woodstock area and the playback and the 3D simulation of the Woodstock movie by using more speakers, as you can see, because we now have 14.1. But we also were using, accordingly with the more speakers, let’s say, a mixed system of upmix and of object-based effects.” The speaker set-up in the Woodstock room is comprised of two layers of seven Neu- mann KH 420 active studio monitors along with two Neumann KH 870s on each layer for a total of 14 speakers and four subs. The first layer is at ear level, about 6 ft. high, and the second layer is near the ceiling at about 20 ft. The two layers of speakers are arranged in a standard seven-channel set up, with left, centre, and right speakers in the front, a speaker on each side, and then two speakers coming from the rear of the room. The room is almost rectangular but with one angled wall and measures roughly 20 m at its widest point. Unlike the London exhibition, which had three screens for front, left, and right, the Montreal exhibition has just one very large, curved screen that is about 20 m wide. Also, in London there was a wooden platform meant to replicate the Woodstock stage that had a drum set and costumes on it. This meant the bottom of the screen was about 3 m off the ground and viewers had to look up at it. At the MMFA, there is no platform, so the screen is only 70 cm from the ground, which Genereux says creates a better effect. “You feel more immersed in the crowd and in the music. You’re not watching a video; you’re inside and with the people, so that is a big change.” To create his 14.1 mix, Warner Brothers gave Zielinsky the stereo recordings from the Woodstock film. “They didn’t give us the actual analog tapes, but it had been wonderfully remastered for digital on 24-bit and I think it was 192 kHz,” he recalls. “The first step is to upmix the music re- cording itself. So first, you take these original recordings and run them, let’s say, through a hand-controlled upmix process. So that pro- cess is based on psychoacoustic effects and, actually, it’s based on so-called Blauert Bands. Jens Blauert was a guy who was working in the ‘50s, already investigating the question: Why and how do we hear three dimensional [sound] even though we only have two ears? He found certain frequency ranges that we react to and the upmix is partially based on these so-called Blauert Bands,” Zielinsky explains. “It is a psychoacoustic trick because we only had two tracks. We cannot take out signals from that and move it around. It is not possible. The only thing you can do is use some psychoacoustic effects and produce, in the first step, a 9.1 sound that leaves the band and the music and the stage in the front, but is also giving you an immersive feeling. We have a system that does this automatically, WOODSTOCK ROOM but we can also do that manually and when we do, we can achieve much better results. And of course, the older the recording is … the more difficult the upmix process is.” The quality of the recordings was not uniform, either. The recordings of Crosby, Stills & Nash and The Who, for example, were very, very good, Zielinsky says, while the recording of Jimi Hendrix’s electric guitar rendition of the “Star Spangled Banner,” one of the de- fining moments of the festival, was nearly in mono and left a lot to be desired. “I think it was like that because originally Hendrix was planned to play at night and then came that thunderstorm and so he played pretty early, like 10 or 11 in the morning, and the techni- cians were not, let’s say, completely ready to record that.” Another trick Zielinsky had to pull off is creating the illusion for the listener that they’re in an ocean of people (there were more than 400,000 people at Woodstock) despite the original recordings not hav- ing very much crowd noise. As it seems, there were no audience microphones set up at the festival, so what crowd noise existed on the tapes was mostly captured by the lead vocal microphone on stage. “You cannot produce an immersive effect out of that, so we took single takes from the original tapes of some places where there was only crowd and processed that, as well, and then moved it around in the 14 speakers. So that means there are two steps; there is the 9.1 upmix of the music itself, and then we add the crowd, which is moved around in those 14 speakers and that helps a lot because now when you have 14 speakers, you can produce a much better immersive effect than with nine speakers, espec ݥѠѡɽݐt)QɕձаAɽͥMչд)ѕа́ѡЁЁѡɥ)]ɥѡͥиā́ɕ̴)ͥٔ䁙ȁѡЁͥٔq'eɕ)ѡɗt́ݡѡɔ́)ѡͽչͥٔɽݐɥ