Collectors of the Koopman complete cantata series need to keep their wits about them following the transfer of the project from Erato to Challenge Classics. Volume 14 is a new release of the last cantatas from Bach’s second annual cycle, a major departure in that the composer employed a consistent strategy of writing a taut opening fantasia around the chorale appropriate to the church calendar (Nos 26, 123, 125 and 178). Bach abandoned the cycle in its established form but Nos 68, 74 and 103 (with texts by Christianne Mariane von Ziegler) and Nos 6 and 42 (the pen of an unknown poet) represent a chronological extension of Bach’s cantata provision for the 1724-25 season. Volume 3 contains cantatas previously released.

Volume 14 is therefore the major event of the two and it contains some highly characterised and compelling performances, none more so than Cantata No 68. This is a Pentecost work of exceptional exuberance as it freely celebrates Christ’s love for the world. Most recognisable is the first aria, ‘Mein glaubiges Herze’ (‘My heart ever faithful’) with its surprising instrumental coda-ritornello of a chuckling trio of violin, oboe and piccolo cello. Deborah York’s forthright singing is effective but marginally less touching than the famously durable reading from Arleen Auger for Helmuth Rilling. The choral and instrumental performances here and in the large choral movements of Nos 178 and 103 are exceptionally refined, revealing Koopman’s instinct for ensemble coloration from the continuo up, his own deft keyboard contributions included. Karl Richter has the edge on Koopman in his reading of No 26, not least in that the transcendent Ernst Haefliger trumps Prégardien’s rather tense delivery in the fine opening aria, ‘So schnell’.

Only in movements of a profoundly projected conceit, as one hears in the opening of the great Easter cantata Bleib bei uns, denn es will Abend werden (No 6) – where the tenderly atmospheric sense of enveloping darkness is masterfully painted by Bach – is there a shortage of true emotional involvement of the kind Christophe Coin provides in his delectable reading. The same can be said of the gentle siciliano E minor chorus of No 125 (like the Trauer Ode, BWV198, this has strong resonances of the St Matthew Passion) where Philippe Herreweghe captures far more of death’s bitter-sweetness.

Yet, the skill of the Amsterdamers is never in question in any of these 11 cantatas (picking out, invidiously, Jonathan Manson’s obbligato cello playing as wonderfully articulate, the oboe section’s playing of biting alertness and Margaret Faultless’s vigorous performance of the solo part in the fragment, BWV1045) even if one still questions, as ever with this series, whether Koopman has as consistent ambitions for the solo vocal movements as he does in the large ensemble movements. Deborah York seems to be left largely to her own devices, as does Klaus Mertens, who appears only intermittently engaged, tending towards a soft-grained objectivity, as he disappointingly reveals in No 74’s ‘Ich gehe hin’. He fares far better in the Satanic imagery of ‘Gleichwie die wilden’ from No 178.

If the arias are somewhat ‘hit-and-miss’ affairs, the fact that so many different singers are involved perhaps contributes to a sense that the roster is one made more from convenience (availability, for example) than a particular feeling for an acutely matched cast. However, I still enjoyed the plucky and communicative singing of contralto Bogna Bartosz and tenor Jorg Dürmüller in the demanding arias from No 74, only really equalled by Ileana Cotrubas and Kurt Equiluz for Helmut Winschermann. The finest performance overall in this volume is No 42 where Koopman brings a suitably recreational air to the Sinfonia in preparation for the eventide of Bartosz’s sultry aria, ‘Wo zwei und drei’ (‘when two or three are gathered’) where each phrase hangs tantalisingly on the still summer air.

The majority of the works from Volume 3 are from Weimar, including a fine Hunt Cantata, a vibrant No 63 and two trial works (Nos 22 and 23), which Bach composed as audition cantatas for Leipzig while employed in Cothen. These are also largely successful, especially the opening movements where, in No 22, Mertens sings as Vox Christi to an uncomprehending band of disciples. It is a deeply sensitive rendering. Other cantatas sound pinched and misjudged; I can’t imagine that Koopman wouldn’t want another crack at Nos 155, 161, 165 and 54 (Widerstehe), where Andreas Scholl and his accompaniment seem to eschew the intensity of Bach’s harmonic world in a decidedly glib reading. As ever, much to admire with Koopman but there are the usual missed opportunities.