Early music is an enormous field, running as it does from the anonymous chansons and church music of medieval composers, through the Baroque and Classical eras and straight into the early decades of Romanticism. So it must be a nearly insurmountable challenge for Timothy Burris, director of the Portland Early Music Festival, to offer an overview of some sort in only three concerts, presented over a single weekend.

The festival, now in its sixth year, is presented by the Portland Conservatory of Music at Woodfords Congregational Church, and Burris’ solution is pragmatic: He suggests the breadth of the repertory by presenting concerts that each look at one corner of it, or sometimes two, with a different focus on each side of the intermission. Between festivals, he offers further adventures in period instrument performance at the chapel in St. Luke’s Cathedral.

This year, the festival’s three concerts included an evening of consort music from the English Renaissance on Friday evening and a Saturday evening concert of Baroque vocal duets, with German music in the first half, Italian in the second. The final concert, a recital by Petra Poláčková, guitarist from the Czech Republic, was on Sunday afternoon.

Poláčková plays an unusual guitar, a nine-string instrument, built in the style of an experimental model that was briefly in vogue in Vienna during the 19th century. Unlike the modern 10-string model championed by Narciso Yepes or the 11-string guitar played by Göran Söllscher, which put the additional strings over a widened fretboard, Poláčková’s instrument is designed like a theorbo, with the extra strings placed to the left of the neck and played as open bass strings. Depending on the tuning, they extend the guitar’s range downward by about an octave.

A thoughtful, technically polished interpreter, Poláčková played a dual-focus program, its first half devoted to German Baroque lute works, with the second half given over to colorful works by Johann Kaspar Mertz, a Hungarian virtuoso-performer who flourished in Vienna during the first half of the 19th century and who played a 10-string guitar, similar to Poláčková’s.

Poláčková began with Sylvius Leopold Weiss’ “Tombeau sur la Mort de M. Comte de Logy” and two movements (an Allemande and a Passacaglia) from Weiss’s Suite XIV in D major – works that proved an ideal introduction to both the guitarist’s interpretive style and the sound of her instrument.

A pedant might complain that Poláčková’s readings, rich with rubato and flexible dynamics and timbres, owed more to 19th century Romantic expressivity than to the style of Weiss’ time (he was an exact contemporary of Bach, with whom he was friendly). But in truth, we can’t know for certain the extent to which lutenists employed those techniques, and even in the period instrument world, players are increasingly open to the emotive approach Poláčková took.

It certainly suited the funereal quality of the piece, and the extended range of Poláčková’s guitar yielded qualities similar to those of the lute, but with the greater volume and body of the modern guitar’s tone.

Bach’s Chaconne, from the Partita No. 2 for Violin (BWV 1004) closed the program’s first half. Poláčková’s tempos were brisk, and they led to a few mishaps, from which she recovered quickly. Overall, she gave a commanding account and used her extra bass strings to good effect, transforming passages that are typically heard as four repeated notes into a version in which the fourth note is dropped an octave. And she played the piece’s fast passage work stunningly.

Mertz, a composer who was virtually unknown until the early 1980s, when guitarists like David Leisner and Nigel North began to champion his freshly discovered scores, is now a staple of the 19th century guitar repertory. Poláčková presented six remarkably varied, multi-layered character sketches from “Bardenklänge” (”Bardic Sounds,” Op. 13) and two of the three “Morceaux” (Op. 65), including the popular “Fantasy Hongroise,” an expansive virtuoso showpiece.

Poláčková was in her element here, executing Mertz’s octave leaps, alternating rolled and plucked chords and call-and-response figures with a sense of drama and an impressive suppleness of timbre. For her encore, she returned to Weiss, giving an elegant, introspective performance of the Sarabande from the composer’s Suite II in D major.

Allan Kozinn was a music critic and culture writer for The New York Times from 1977 to 2014, and is the author of several books, including “The Guitar: The History, The Players, The Music” (Quill, 1984). He lives in Portland. He can be contacted at:

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