The Eckoo is powerful, quick and flexible. It can be installed independently in exhibitions to resonate and can be utilized for live playing. Using a computer the compositions can vary within certain borders, with sufficient recognizable parts for frequent visits. The Eckoo evolved from the overview exhibition in 2002, Primal sound, in which all parts were transmitted by computer; it was, as it were, one huge musical instrument. For that exhibition new sound groups had been devised: flute clusters, pan flutes and basses. For those parts Hans van Koolwijk thereafter designed a console. He did this in collaboration with Hans van Eck, whose name became part of the title Eckoo (Eck & Koolwijk). The console has many bolts and knobs. When placement of the Eckoo is broad and flat, it can fill large spaces with sounds, which for the visitor seems to come from all directions.

A bass box is an electric air pump which pumps exact wind gusts into flutes, producing rhythmic, percussion-like sounds. The bamboo flutes are capable of easily being `overblown' and are sensitive to fast, small alterations in pressure. Between two airtight chambers in a firm transportation box, the pump is in the shape of a large bass loudspeaker. This builds up a high-speed pressure in the left and right chamber and as a result the flutes, which are connected to those chambers, suctioning successively in and out. The fast `panting' creates nuanced harmonics in the flutes. Since the flute sounds are fairly soft, they are amplified. With the Pulsor - an analogue synthesizer without keys and presets - the player creates pulsations, which are sent by means of two large amplifiers to the bass loudspeakers. These shift considerably up and down and create two flute sounds per bass box, with a total of four, which are all linked together. For the amplification of flute sounds four microphones transmit their signals by means of a mixing console to two stereo amplifiers which have been placed under the bass boxes. From that point cables connect to four excellent resonating loudspeakers. This is an intimate and meditative instrument that produces clean, noble and noise-free sounds and retains a subtle status between the other works.