For nearly 30 years, Tetsu Saito of Japan has been playing the fiddle bass.

"I don't know why," he said in a phone conversation earlier this week, after arriving from Tokyo via Maui, where he gave a weekend performance.

"Basically, I love low notes. And a bass has low notes. I guess I like the sound of it."

Saito, 50, is here with Japanese colleague Nobuyoshi Ino for the week-long fourth Biennial Hawai'i Contrabass Festival, which climaxes with a concert tonight at the Doris Duke Theatre. Another concert will be held Saturday at the University of Hawai'i-Manoa's Orvis Auditorium with another eminent bassist, John Clayton Jr.

When contrabassists — those who play the basses with the lowest tones possible — get together every two years, what do they share?

The lowdown on the lowest of all instruments, of course.

"We share the music with each other; we will play my compositions," said Saito. His surname sometimes is spelled Saitoh, but he said he prefers it without the h.

Saito has arranged music for two basses "designed for normal jazz musicians to become more free," he said, through techniques such as improvisation.

He said he began playing the bass at age 22, learning by himself but later studying with Keizo Mizoiri, a high school classmate, and his ally, Ino. Over the years, Saito has emerged as a musical chameleon, playing with and arranging for a tango orchestra, directing a theater group called TAO, recording numerous CDs, bridging diverse cultures and traditions in the process.

"I am influenced by the countries I visit," he said.

"In my own culture, I studied traditional music, Asian music. But I've wanted to be unique, so no one can take my place."

It was an initial challenge, said Saito, "because the bass was made in a Western culture and I happened to be an Oriental from the East."

His collaborations are varied, with links to Korean artists and koto players, with European bassists and American jazz stylists.

Saito also is noted for his unusual tunings for the bass.

"I invented many ways of playing bass, so it's this technique that I like to share with young bassists everywhere," said Saito.

He expressed his philosophy on the contrabass and its deep tones.

"It covers all the pitches, all the ranges, and it can sound off all the rhythmic things in music," he said. "Where the piano can sound only half-tones, the bass can sound every minimal note."

He said he plays on only one instrument, an 1880s find in Belgium "that was very expensive." He had swapped a bass he owned for this one, which has become his trusty sidekick. Besides the "old" sound he said the instrument produces, as opposed to a "young" sound from a bass fiddle he exchanged, "my instrument is famous for the lion head it has, not the normal scroll. It's very unusual."

Reach Wayne Harada at wharada@honoluluadvertiser.com.