||Early in 1991 I received a commission from Professor Hans Landesmann, the person responsible for the concert planning of the Salzburger Festspiele, to compose a string quartet. The Arditti Quartet was to play the world première in 1994.
My first reaction was - as often before in such cases - that I would not write a string quartet, because I have never separated form, content and performance practice, and the string quartet is a typical genre of the 18th century.
Similarly, for 45 years, I have not written symphonies, sonatas, piano concertos, violin concertos etc. Each of my works has its own form, instrumentation, performance practice.
And then I had a dream: I heard and saw the four string players in four helicopters flying in the air and playing. At the same time I saw people on the ground seated in an audio-visual hall, others were standing outdoors on a large public plaza. In front of them, four towers of television screens and loudspeakers had been set up: at the left, half-left, half-right, right. At each of the four positions one of the four string players could be heard and seen in close-up.
Most of the time, the string players played tremoli which blended so well with the timbres and the rhythms of the rotor blades that the helicopters sounded like musical instruments.
When I woke up, I strongly felt that something had been communicated to me which I never would have thought of on my own. I did not tell anyone anything about it
Since I did not, after the dream, have any time to compose, I wrote and drew several sketches and - from the super formula - developed the HELICOPTER STRING QUARTET as the third scene of WEDNESDAY from LIGHT (LICHT), the cycle of music dramas which I have been composing since 1977.
Only in 1992/93 did I find the peace to compose the HELICOPTER STRING QUARTET, and especially to make the fair copy of the coloured score.
A performance is staged in the following way:
First, the four string players are introduced to the audience by a moderator - who may also be the sound projectionist. He briefly describes the technical aspects of the forthcoming performance. Then, the players walk to the helicopters - or are driven there - while being constantly followed by video cameras which transmit to the television monitors. The moderator (at the mixing console) explains over the loudspeakers what is happening.
From their embarkation into the helicopters until they disembark, each string player and his helicopter is transmitted via camera, television transmitter, three microphones and sound transmitters to his own group of monitors for the audience. Each string player should be constantly audible and always visible close-up – face, hands, bow, instrument – without any camera changes and without the fading in of other pictures.
Behind each player, the earth can be seen through the glass cockpit of the helicopter.
The ascent lasts about 5 minutes from the ignition of the turbines to bar e1™. Until the world première, the measured music of the score (starting at bar e1™) lasted 18! minutes. Due to a later addition, it now lasts circa 21! minutes. Descent and landing last about 5 minutes each.
The microphone transmission from each helicopter should be such that the sounds of the rotor blades and that of the instrument blend well, and the instrument is heard slightly louder. To achieve this, at least 3 microphones per helicopter are necessary: 1 contact microphone on the bridge of the instrument, 1 microphone in front of the mouth of the player, and 1 microphone outside the helicopter which clearly picks up the sounds and rhythms of the rotor blades. The 4 x 3 microphone signals can be transmitted by 12 individual transmitters – possibly via satellite relay – and received at the concert hall as well as at further localities, then balanced and mixed to 4 mono signals at a mixing console using 4 x 3 faders.
From the moment the synchronous playing begins (0’00”) until it ends (21’37.8”), the four helicopters circle within a radius of circa 6 km above the performance venue, individually varying their flying altitudes. They should fly so high that the direct sound of the rotor blades is much softer than the sound coming from the loudspeakers, or even better, inaudible.
After the landing, cameras follow the string players and the four pilots as they disembark from the helicopters and walk (ride) to the concert hall. Once in the auditorium, the pilots are also introduced by the moderator. The players and pilots are asked about their experiences, and finally the audience is invited to participate in the discussion.
In performances independent of WEDNESDAY from LIGHT, at least three successive flights should take place in daylight with an appropriate period of time between flights, and with different audiences. As third scene of the opera, only one flight takes place, also in daylight.
The composition is through-structured to the tenth of a second. The players are synchronised using a click-track which is transmitted up to them in the helicopters, and which they hear over earphones. Since the four string players usually tremolo in criss-crossing glissandi, I had to draw their pitch lines and curves on top of one another in four colours, so that the melody trajectories could be followed.
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In the autumn of 1993 I sent the score to Professor Landesmann in Salzburg, slightly nervous at the possibility of him exploding in dismay. Amazingly enough, his response and that of the general director of the Festspiele, Dr. Gerard Mortier, was unexpectedly positive, inspired and courageous. A long series of negotiations followed between the direction of the Festspiele and the Austrian army for obtaining the helicopters, with the Austrian radio and television for obtaining the necessary 12 audio and 4 video transmission-channels, and with officials for obtaining the many necessary permits. I received photographs of a cellist playing in a helicopter, tape recordings made using various microphones, and copies of documents.
I called Irvine Arditti only after the Festspiele had accepted my score. His first words were: “Wow – wow – wow!” Whatever that meant: I was happy that he did not give up at once. However, he soon tried to convince me to allow the quartet to be performed without helicopters, using a tape of helicopter sounds, a suggestion to which I reacted quite crossly (naturally, he could not imagine what I had experienced in the dream).
Soon afterwards, I sent him four colour photocopies of the score and a click-track tape which my son Simon had made, on which each bar number is spoken in English, and the beats of each bar are marked by impulses and counted in German.
Despite the efforts of the Festspiele direction, the performance planned for 1994 could not take place. I was told that the Green political party had publicly warned that it would be intolerable for the environment to allow four helicopters to fly above Salzburg just for the music of Stockhausen, and that the general director of the Austrian television and radio had therefore set such astronomically high rental fees for the equipment, that everything became too expensive.
I told this story to Jan van Vlijmen, the director of the Holland Festival. At first, he did not say anything. But he must have been infected by my dream. Heaven knows how he managed to get all of the permits and sponsors. In any case, he allowed several experiments to be made, but only in mid-April 1995 did he send me the news that the HELICOPTER STRING QUARTET would definitely be performed three times on June 26th 1995 in Amsterdam.
On December 14th 1994, Irvine Arditti took part in the first tests at the airfield in Deelen, Holland. He told me afterwards that everything seemed to work.
During the rehearsals in four separate rooms, I was in a control studio and heard the string players – whose playing was picked up by 4 microphones – individually over 4 loudspeakers.
The arrangement of the loudspeakers was as it should be in a performance:
left half-left half-right right
violoncello viola 2nd violin 1st violin
During these rehearsals I spoke with the musicians via microphone and loudspeakers, and recorded all sections using an 8-track tape recorder. At regular intervals, the players came into the studio and listened to the recordings.
The tape of these partial recordings and a complete recording is in the archives of the Stockhausen Foundation for Music.
On May 10th 1995 further microphone and transmission tests followed at the airfield in Deelen. During these tests, both a small battery-powered mixer in the helicopter (for the distribution of the signals to the transmitter and earphones) was used, as well as a mixer at the ground station where the signals were mixed and recorded.
On June 8th, also in Deelen, Irvine Arditti and Rohan de Saram (in helicopters) tried out special stringed instruments with contact microphones, various microphones, transmitters, receivers and the mixing console.
Finally, on June 24th 1995 at the grounds of the Westergasfabriek in Amsterdam, all technical equipment was set up in a specially fitted auditorium, and on June 25th the final rehearsals began, with four helicopters.
After I had tested all of the technical transmission units in the helicopters, I prepared the mixing console, and tested all of the equipment. Two test performances were flown, recorded on 12 channels and each time listened to by all participants, commentated and corrected. Also the presentation of the musicians and pilots was rehearsed, with myself as moderator.
For the world première on June 26th, three flights took place at 4:30, 6:30 and 8:30 p.m., for different audiences, each time introduced by me and followed by a discussion.
All rehearsal flights and performances were recorded on film and 16-track tape. The recordings were made on 32 tracks (4 x Tascam DA-88):
2 x 12 channels for recording the rehearsals and performances and for security copies. The Dutch radio recorded a stereo mix of these channels on DAT. Some of these documents are in the archives of the Stockhausen Foundation for Music. Most of the filming was done by Allegri, a Dutch company.
After the world première, I added a circa 3-minute, synchronous Formation to the end of the work before DESCENT and LANDING.
HELICOPTER STRING QUARTET ist dedicated to all astronauts.
World première: The cameras were installed in the helicopters, the support equipment and personnel were on the airfield. All proceedings between the auditorium and the helicopters at the take-off and landing points as well as an initial and final presentation were directly transmitted by portable cameras. 4 music stands, installed in the helicopters.
4 x 3 microphones with 4 x 3 transmitter-receivers; per player:
1 contact microphone on the bridge of the instrument,
1 speech microphone in front of the mouth,
1 large outboard microphone for the rotor blade sounds.
The 4 x 3 microphone signals may also be received via satellite relay.
World première: After numerous experiments for positioning the outboard microphones, they were fastened to the boarding stairs below the doors of the helicopters and covered with special wind-shields. Due to safety regulations, there was no other possibility.
The Sprechgesang of the players (speech-singing of numbers), which was picked up by the speech microphones, was transmitted via the video transmitters. The signals of the contact microphones and outboard microphones were transmitted via 4 x 2 audio transmitters. 8 closed earphones (tightly fitting) for the 4 players and 4 sound technicians.
1 click-track tape: For rehearsals and performances, Simon Stockhausen made a 2-track tape, the left track of which is a voice counting the 1st beat of each bar in English and all further beats in German; on the right track, the 1st beat of each bar is marked with a high impulse and each following beat with a lower impulse. A copy of this tape with exchanged tracks is also available. There are slight timing discrepancies between the tape and the score. These resulted from approximations of the metronomic tempi during the production of the click-track tape.
The players originally asked to hear the counting voice of the click-track tape in one ear and the impulses in the other ear, and their instrument and voice in both ears.
Voice and impulses were recorded separately on the two channels, so that the balance between them could be individually regulated. Originally, we had made a mono mix of both signals, but the players could not hear the voice loud enough when the impulses were sufficiently loud. The voice was covered by the noises in the helicopter.
The click-track was transmitted by a mono transmitter, and thus the balance between voice and impulses was controlled at the ground station and could not be altered in the helicopter. The players therefore heard – in the end – voice, impulses and their own instrument on both ears.
Each player had a different mix of the microphones and click-track which could be altered during the rehearsals.
World première: A sound technician sat in each helicopter vis-à-vis the string player, and operated a small mixer, balancing the levels of the 3 microphones and that of the click-track tape for the player’s earphones. 4 columns of television monitors in the concert hall.