Hans Tutschku

behind the light

for string quartet and electronics
year: 2011
duration: 15:00 min
studio: Harvard University
dedicated to my father
first performance: November 16, 2011 by Chiara Quartet , Sanders Theatre, Cambridge MA

behind the light is a reflection on reflections. What surfaces are capable of reflecting incoming light? How does this alter color and how do the qualities of the reflections change the visual atmosphere? behind the light is an exploration of the relationship between source and multiplication. I reimagined the flickering quality of sunlight on a river, the neutral atmosphere of light tubes in a hallway, or the moving shadows created by a burning candle in the musical world. They inspired relationships between sonic characters and the explorations of the string quartet and electronics. I’m interested in concepts of verticality and horizontality: the ensemble and the electronics often develop their own wanderings for short periods of time, but then are resynchronized by strong vertical events. The electronics were composed using prior recorded and manipulated string quartet sequences.

first performance with the Chiara Quartet




This composition uses an iPad to play back the prepared sounds.

The electronics are divided into separate events, to be triggered by the first violin at the indicated moments in the score.
There is no other method of synchronization and no use of a click track. I prefer that the musicians are interpreting their part and that the electronics are re-aligned at the beginning of each event to that interpretation.

Triggering the events can be done two ways:

  • using an AirTurn PED pedal (see below)
  • using BlueBoard with a sustain pedal (see below)



The iPad should be positioned on an extra music stand, next to the first violin. Its mini jack output is connected to two small, high-quality loudspeakers, placed on the floor in front of the quartet. Depending on the hall acoustics, these speakers should be angled slightly outwards to enhance the stereo image. There is no need for microphones nor additional loudspeakers in the concert hall.

The speakers on the floor should be angled by approximately 45 degrees so that the sound is not pointed directly to the audience but rather bounces off reflective surfaces in the hall and therefore mixes more naturally with the sound of the string quartet. It should not give the impression that the sounds are coming straight out of the speakers and a hight degree of sonic fusion with the live quartet should be obtained.

These Fostex 6301B Monitors have proven to be a good solution in smaller venues.



The mini-jack output of the iPad is connected to the Fostex monitors with a cable TRS 1/8 inch – TRS 1/4 inch and a headphone extension cord.


installing the software

Download the application ‘behind the light’ from the Apple AppStore (see link at the end of this page).
After launching it for the first time, the sound files need to be downloaded. Press OK.

iPad interface

The main screen contains the following elements:

The white progress bar on the top scrolls from left to right over the ‘ideal’ duration of the event. If the performers choose a slightly faster tempo, the following event can be triggered early. The previous event will fade out to ensure a continuous sound from the electronics. If they perform at a slower tempo, the electronics of the current event will continue for a few seconds. When the quartet reaches the next event in the score, the next event will be triggered and re-synchronizes the electronics to their performance.

After starting an event, the touch button and pedal are disengaged till two seconds before the next event to avoid accidental triggering.

The large number in the upper center indicates the current event.

The ‘prepared cue’ on the upper left shows the next event to be triggered. Touching the number brings up the cue selection screen to maneuver to a different event during the rehearsal process.

One can also go to adjacent events with the Prev/Next buttons. The volume slider controls the general playback volume.

The upper right area holds information about the bar structure and tempo. It can also be used as a visual metronome, where downbeats flash the full surface of the rectangle with a white color, whereas upbeats only fill the rightmost third of the rectangle. The visual metronome needs to be enabled in the settings dialog (see below).

The application also provides an audible metronome for rehearsal purposes. If activated in the settings (see below), two additional sliders appear at the upper right:

The volume slider controls the volume of the metronome. By bringing the volume of the electronics (next to the stop button) to zero, one can rehearse with the metronome only. The rate slider permits to rehearse at a slower tempo (50-100%). If the rate is not at 100%, playback of the electronics is muted.


Settings dialog

The loudspeaker test should be performed to check that the cabling of the speakers is performed correctly and that both speakers are working. Switching the tuning sound on gives the possibility to tune the iPad to a reference pitch. The next two buttons control the metronome.


Scrolling further down on the settings:

Autoplay is another option for rehearsals, where all events are triggered without input from the touch button or pedal.

AirTurn brings up the menu to pair an AirTurn PED pedal.

The first generation of AirTurn BT-105 is not recommended as the BlueTooth protocol is different and triggering introduces an unpredictable delay between the action and the start of the sound file.


To pair the AirTurn PED, enable the AirTurn Support and press ‘My device is a PED.’


Press the on/off button (1) on the PED. Press button 2 and release after the first red flash on the battery symbol. This switches the PED into PED-APP-Direct mode.


If no device is found, press button 1 on the AirTurn for 7 seconds to reset Bluetooth pairing. After the device turns off, press button 1 again.


Once the AirTurn is found, the following messages need to be confirmed.

Exit the settings dialog by tapping on a different area of the main screen.


Using the BlueBoard with a sustain pedal

An alternate way of triggering the sound files is by using the BlueBoard and attaching a MIDI sustain pedal to the external input one.

Start the BlueBoard application before opening ‘behind the light.’

Calibrate the foot pedal for EXT 1, then open ‘behind the light.’ Pressing the sustain pedal will trigger the next event as ‘behind the light’ is listening to the MIDI messages sent from the BlueBoard application.


update events

The electronic score is stored in a database on the device, independent of the sound files. Each event is marked in the musical score with a number. Each event contains the information as to which sound file to play, volume, durations, etc. If corrections to this electronic score become necessary, the musician can download a new database. This provides a possibility for corrections, without downloading the entire application anew. The location of this updated file is known to the application. Thus no further information is necessary. Just press the button and wait for the confirmation message. For the update to work, you need obviously a connection to the internet – through the phone provider or WIFI.

update sound files

Similarly to the events, sound files can be updated to the latest version.









download app from app store


back to top