The instruments are so big they look like art installations. Take the Earth Harp, which, at 300 metres in length, is the world's longest stringed instrument.

Along with the snowflake-shaped Drum Cloud, the fish-like Aquatar, the Drum Orb, and dynamic musical shows, the band quickly won worldwide acclaim. It has performed in the ancient Colosseum in Rome and Washington DC's John F. Kennedy Centre.

'We've even staged a show in a traditional temple in Hanoi, Vietnam. That was the most special performance.'

Close studied sculpture, sound design and art at the Art Institute in Chicago. A lover of music, architecture and visual art, he decided to design instruments based on nature.

'The concept of the Earth Harp is to use the Earth as part of the instrument. At its debut, we stretched the strings across a valley - it was 300 metres long.'

A new instrument can take anything from a week to two years to create. The first thing planned is appearance - each instrument is a piece of art.

Then comes sound. The band members look for and test materials - usually wood and aluminium - until they find the sound they are looking for.

The inventions use the basic principles of conventional instruments, such as the vibration of strings.

But there are technical differences. For example, the Earth Harp is played by running a gloved hand along the strings instead of plucking them.

'[The large instruments] are actually easier to learn ... we have 30 unique instruments to use in performances.

'We often invite the audience to come up on stage and learn. Their response is enthusiastic,' says Close.

The 14 band members, aged 25 to 37, come from diverse backgrounds and disciplines, and from all over the world.

They all work on the different aspects of the band: from creating the instruments and writing music to choreographing performances. Six of them will be in Hong Kong at the end of the month.

'The biggest challenge is installing the instruments. We have to get the floor plan of the performance venue in advance and see how far we can stretch the strings. For the Hong Kong show, we're going to set up 30-metre-long strings, from the stage, over the audience, and to another building.'

MASS Ensemble will perform at New Town Plaza on December 22-26 and December 29-21 at 4.30pm and 8pm.

Immense instrument

The world's largest musical instrument is the Boardwalk Hall Auditorium Organ in the Main Auditorium of the Boardwalk Hall in Atlantic City, New Jersey, USA.

It also holds the Guinness World Record for the loudest musical instrument and the largest pipe organ ever constructed. It is made of at least 33,114 pipes - the actual number is unknown.

Due to its poor condition, the organ is no longer functional.