72-year-old Barenboim launched the instrument yesterday at the Royal Festival Hall here, in advance of his Schubert recital series.
Declaring the new piano a "sound alternative", Barenboim said: "I've fallen in love with it and I want to spend as much time with it as possible."
The exterior of the new piano looks much the same as any other modern concert grand piano but inside there are some dramatic differences, The Guardian reported.
Barenboim, currently heading Berlin's flagship opera house, the State Opera, said he intends to perform the entire series on the new piano.
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Modern pianos have become highly standardised, with few changes to their fundamental design over the last 100 years.
They are largely cross-strung, with the bass strings crossing over the middle and treble strings in an "x" pattern, allowing the sound to be concentrated on the centre of the soundboard.
"The warmth and tonal characteristics of the traditional straight-strung instruments is so different from the homogenous tone produced by the modern piano across its entire range," he was quoted as saying by the BBC.
He developed his idea with Belgian instrument maker Chris Maene, with support from Steinway & Sons.
According to a press release, the piano "combines the touch, stability, and power of a modern piano with the transparent sound quality and distinguishable colour registers of more historic instruments".