The Inspiration

Built on a huge hill of debris of World War ll. the Radarstation used by the NSA during the Cold War rises on the horizon of Berlin. Today it’s abandoned.

I have a personal connection to this place. Not far from our Student Dormitory in Grunewald, we used to climb up there during the nights with our Instruments making music in one of the most bizarre acoustics while having an amazing view. We are also organizing an official concert every year on top of it.

When I heard about the 3D Audio competition from my professor I immediately thought it would be awesome to capture the acoustic of the dome.

It is a completely spherical room about 10 meters in diameter, it has completely reflective walls and an reverberation about 15 to 20 seconds long. Due to the spherical shape it has some interesting early reflection patterns. If you stand directly in the middle you will get a perfect echo.

The Idea

The Idea is to record single phrases from different positions inside the dome and layer them in the end. So for Example the blue triangle will be a triad and the red one will be another one. Both of them together give an hexagon, which is the shape the dome is constructed of.

I used also other geometrical shapes for positioning the musicians. The reverberation should bring the separate notes together again and give a wide and surrounding chord.

I decided for slow tempo of 66 bpm because the reverberation time is extremely long and will blend notes into each other. I also decided to compose in a 6/8 time signature to implement the hexagonal shape also into the music.

The composition should embody the specific atmosphere of this place:

Peaceful – Majestic – Transience – Old – Dead – Mystical – Historical

The piece was written for Violin, Guitar and Bass. I choose D as a root note because it has a resonance in the dome. Also the whole tuning is changed from 440Hz to 433,7Hz which gives an octave of the orbit time of the planet Mars.

The Recording

I used 6 Microphones in total to capture the dome and the instruments:

4 AKG C414 Cardioid: They were place in a square of 2m towards every corner facing the different musician positions.

1 Soundfield ST450 MKII. Placed in the middle of the dome to capture the reverberation.

1 AKG C411 PP: Glued onto the instrument to get a dry Signal.

For the recording I used an Sounddevices 788T for the best signal/noise ratio. I also took Impulse Responses from different Positions to use them as a reverb for my sound effects.

Results and Problems

It took some time to get all the microphones, recorders, musicians and the agreement of the owners. The earliest recording everybody agreed on was Monday 26. June.

It was a difficult tasked to write a piece without trying it out inside once before the recording.

We couldn’t forbid the tourist to enter because they paid for it. That was a major problem cause they ruined a lot of recordings by entering and making noises. Even the smallest noises are very loud inside.

Also there is no electricity so we had to carry enough battery’s for the recording.

Sadly I forgot to bring lights with me. It is dark inside the dome so the musicians had problems to read the notes. To my bad surprise this ended up in playing some wrong notes, which was really difficult to fix afterwards.

This project took a lot of effort and I’m happy with what I learned about 3D audio. I would appreciate to hear my piece on your conference.

With kind regards,

Ramón Wiegratz