Dressed simply but smartly in a black suit and tie, hair neatly coiffed, Rinaldo Alessandrini looked as much like an expert witness as guest conductor and soloist with Handel and Haydn Society on Friday night, October 28 (to be repeated on Sunday afternoon). Appearances proved telling, as Alessandrini got down to business beautifully in a program of Geminiani, Bach and Pergolesi at Jordan Hall. As founder and director of the Concerto Italiano, Alessandrini’s insight and élan for Baroque music translated into tight, thrilling results from the Society orchestra as well as Alessandrini’s harpsichord. Unfortunately, their winning technical execution and dramatic conception overshadowed the featured vocalists in the main works.

The evening began with Alessandrini coaxing crisp, glowing textures from Geminiani’s Concerto Grosso in E Minor, Op. 3, No. 3. Italian-born Francesco Geminiani (1687-1762) studied in Rome under Corelli and rose to critical and popular acclaim in London. Geminiani’s concerto references his teacher while exploring his own more intense style and expands the concertino solo group to two violins, viola and cello. Soloists and ensemble dug into Geminiani’s chromatic lines, chattering imitations and gently melancholic “Adagio” before Alessandrini’s seamless guidance into the driving “Allegro” finale. His sashaying tempos and pinpoint cadences were precise yet organic throughout, and the orchestra clearly benefited from (and enjoyed) his direction.

The same approach guided the orchestral accompaniment for Pergolesi’s Salve Regina in C Minor. Giovanni Pergolesi (1710-1736) composed this work as well as the Stabat Mater shortly before his young death. His style keeps one foot in the sturdy counterpoint and motor rhythms of the Baroque and another in the simpler, more direct approach of the Classical era. Alessandrini’s ear for textural balance and energetic tempos illuminated the figures behind soprano Liesbeth Devos, with some imploring violins during the final “O Clemens, O Pia, O Dulcis.”

Devos’s cool, sweet soprano displayed precise timing, and she executed Pergolesi’s decorous lines effectively, yet more textual involvement would have placed the emotional thrust back in the vocal part rather than the instruments. At times the work seemed to tax the young singer, with sustained notes wavering and her emphasis on the sighing gestures of “Ad te suspiramus” sounding labored.

Following the gravity of Pergolesi’s work, Bach’s Harpsichord Concerto No. 3 in D Major, BWV 1054, closed the first half of the concert with Alessandrini gracefully sliding into the first movement’s tumbling phrases, subtly weaving in and out of the orchestra during the pensive second movement and dancing elegantly through the third movement. Carefully separating the harpsichord’s role as continuo instrument and soloist allowed for rewarding contrasts, and Alessandrini’s perfectly judged tempos kept things articulate without degenerating into the sewing-machine effect of some interpretations. The orchestra was clearly pleased, smiling behind Alessandrini’s solos, stomping feet during applause and refusing to take a second bow before Alessandrini himself took another.

The tearful suspensions and doleful bass lines of Pergolesi’s Stabat Mater welcomed the audience back after intermission, with mezzo Emily Righter joining Devos onstage. While composed as a sacred work, Pergolesi’s work betrays his experience as an opera composer in shimmering vocal lines, dramatic pauses, and springy rhythms. Righter’s rich, full voice audibly relished such theatricality, yet she encountered some awkward blends with Devos, especially during the opening stanza and at “Pro peccatis…” “Fac, ut ardeat…” came across much better, with clear lines, soaring voices, and a palpable desperation.

These are young singers with young voices and ample potential, and if they keep singing alongside such estimable company, there is much to look forward to. Righter started out strong in solo, with a shivering “Quae moerebat…” but by the middle stanza of “Eia Mater,” her voice seemed to flag, with unsteady dips into the lower register and sustained notes lacking body. Instead of heaving grief, the effect was merely breathy. On the other hand, while Devos’s technical delivery was once again flawless —the leaps of “Vidit suum…” were truly heartrending — for the most part the soprano sounded detached from this beseeching, at times violent, text.

Some listeners may have found Alessandrini’s tempos excessive, but his direction depicted the energy of grief while making sure the work never turned ponderous,  though the galloping “Inflammatus…” approached self-parody). The strings turned from icily descriptive to warmly comforting, and their aching commentary behind the singers on “O quam tristis…” stole the show. The penultimate “Quando corpus…” was the evening’s highlight, with a contemplative tempo, suitably desiccated violins and the vocalists’ purest harmonies. Friday evening’s performance offered huge emotional impact, even if it didn’t always come from where expected.

This program will be repeated on Sunday, October 30 at 3:00pm in Jordan Hall. Tickets are available for purchase by calling NEC’s Jordan Hall Box Office at (617) 585-1260.

Andrew J. Sammut also writes for Early Music America and All About Jazz and blogs on a variety of music at clefpalette.wordpress.com. He also plays clarinet and lives in Cambridge.