The Royal Albert Hall is not kind to small early-music ensembles, especially when their Prom is scheduled for the late-night slot, when there are generally fewer audience members to pad out the walls and correct for the hall’s capricious acoustic.

Solomon’s Knot did an excellent job with their all-Bach programme, but adding an extra trumpet to the composer’s three-part scoring, and setting this (along with three oboes, bassoon, timpani, strings and continuo) against just eight voices was always going to present audibility challenges in the tutti sections. The Promenaders probably got the best of it, but for those of us in the posh seats, a lot of the performance (apart from the trumpets and drums) sounded as though it was underwater.

Michaelmas is an important date in the Lutheran calendar, and Bach’s mind-blowingly effusive cantata output in his early years at Leipzig included four lavishly orchestrated cantatas for the feast of the Archangel: Es erhub sich ein Streit (BWV 19); Herr Gott, dich loben alle wir (BWV 130); Man singet mit Freuden vom Sieg (BWV 149); and Nun ist das Heil und die Kraft (BWV 50, from which only the opening chorus has survived). Solomon’s Knot’s presentation of all of them was a cleverly thematic construction, as it made not only for efficiency in instrumentation, but the combination of arias and recitatives allowed each of the eight singers a moment in the sun.

The performances were as crisp and historically informed as you’d want (the gradual addition of orchestral forces for the chorale ‘Ach Herr, lass dein lieb Engelein’ was particularly impressive), and came with the added thrill of being entirely unconducted; in yet another improvement to engagement with the audience, the singers sang completely off-book.

All of the solo movements were performed with an admirable understanding of idiom, but the acoustic favoured some more than others. Clare Lloyd-Griffiths’ ‘Gott schickt uns Mahanaim zu’ had a tender lilting quality to it, but she was slightly swamped by the two oboes and bassoon, whose tones pierced better the acoustic veil. Zoe Brookshaw’s voice, though, with its powerful sweetness, was able to cut through the string texture to deliver a radiant ‘Gottes Engel weichen nie’. A similar contrast could be heard in the two basses. While Jonathan Sells’ recitatives were relatively clear, there were moments in ‘Der alte Drache’ when he lost the contest against the trumpets; Alex Ashworth’s voice, however, has an extra heft and resonance, such that ‘Kraft und Stärke’ rang out as clear as a bell.

Roderick Morris’s recitatives came across loud and clear, and the voice of his fellow alto Kate Symonds-Joy blended beautifully with that of tenor Thomas Herford for ‘Seid wachsam, ihr heiligen Wächter. Sadly, the tenors didn’t come across clearly in their solo movements, and despite excellent interpretations, neither Thomas Herford’s ‘Lass, O Fürst der Cherubinen’ (notwithstanding the charming flute obbligato supplied by Eva Caballero) nor Andrew Tortise’s ‘Bleibt, ihr Engel’ achieved the effect that the performers so clearly wished to deliver.

The fragment of Cantata 50, with its complex two-choir contrapuntal writing was always going to be a challenge, and so it was. It was probably wonderful from close up, but the busy counterpoint was swallowed up by the space and the generous instrumentation.

Gold star of the evening, though, goes to Inga Maria Klaucke, whose bassoon obbligati (also without score) for ‘Kraft und Stärke’ and ‘Seid wachsam’ provided some technically accomplished vignettes of bubbling joy.