For a musical superstar, Jordi Savall is a quiet man, both in speech and in the volume at which he plays. But make no mistake: beneath the quiet exterior lurk intensity, vivacity, joy, knowledge and all manner of technical skills. The intimate, candlelit surroundings of the Sam Wanamaker Playhouse made a perfect backdrop for Savall to display these virtues at their best, with the assistance of just one other musician: multi-instrumentalist Dimitri Psonis.

A Savall concert is as much an educational voyage as a musical one. Over the years, Savall has made it his business to explore the medieval and renaissance music of many places and many traditions, and he speaks about the music with thoughtfulness, love and authority. Last night’s concert, the second of two on the day, took us to Istanbul at the zenith of the Ottoman Empire. Music being considered something of a second-class occupation, the musicians came from many ethnicities: Armenians, Greeks and Sephardic Jews mingled with Turks and Arabs; the concert was designed to give us a sampling of all these styles and the way they intermingled.

What strikes most about Savall’s playing is his sense of rhythm, which has much in common with the best folk musicians today. When he plays a fast folk dance, it seems on the surface to be in strict tempo – you would be utterly confident of your dance steps. But underneath, he is taking all manner of liberties with the rhythm, pulling notes hither and thither to suit the shape of the phrase that he is crafting. The term tempo rubato means “stolen time” in Italian: that makes Savall a persistent and prolific criminal – but one who always pays his debts as he ensures your sense of rhythmic solidity.

I was awestruck by Savall’s ability to produce decorations at speed. When in a lively dance number, the basic tempo could be quite quick, but filigree patterns would be woven around the basic line, always with a sense of grace, never impairing the basic pulse. These may be compositions that lack the complex trickery added by composers of the baroque period and later, but they struck me as music of the utmost refinement. 

He played three different instruments of the “medieval fiddle” family, all held between the legs viola-da-gamba style. Each gave a different timbre: the smallest, the rebec, was the clearest; the mid-sized vielle was more full-bodied; the larger rubab the deepest and most sonorous. His partner, Dimitri Psonis, played a variety of drums and tambourines, the santur (of the hammer dulcimer family) and two eastern lute-like instruments, the oud and the saz.

You don’t normally apply the words “gentle” and “subtle” to drummers, but Psonis was highly impressive in extracting a range of tones from drums at a volume which perfectly suited his partner’s relatively soft stringed instruments. When playing with sticks, much was around the edges of the drum, particularly the large Ramadan-procession bass drum; when playing with hands, he would sometimes use just fingers to produce different a roll of drum beats, each in a slightly varied tone.

The oud is a fretless instrument, which gave Psonis the ability to bend notes with the left hand – not for vibrato, but to create a shape of note which gave the concert its most characteristic Eastern flair (the oud could also be strummed or plucked without bending notes, sounding more like a lute). My favourite of his instruments was the santur, which he played with great virtuosity to give silvery patterns of notes – again, with a characteristically Eastern touch.

I’m going to confess that apart from the occasional obviously Sephardic or Arab scale, I don’t feel very much further forward in picking exactly what was what between the Greek, Armenian or Turkish pieces. But I was entranced by the playing of these two musicians. The faster dances were full of energy and wit – no more so than when Savall finished one by accelerating away from Psonis, who struggled to follow him. The slower pieces were narcotic, calming me and genuinely putting me into an altered mental state. An experience not to be missed.