In a nutshell:• Arguably the superlative volume in CPO’s survey, containing three quartets from Onslow's output.• I’m convinced the String Quartet No. 4 in C minor op. 8 (1817) is Onslow’s greatest early work. It compares well with Beethoven's op. 59 owing to its originality, soul-stirring emotion, and exhilarating energy. The toccata-like finale is a tour-de-force.• String Quartet No. 25 in B-flat major op. 50 (1834) once shared space on programs with quartets by Beethoven and Schubert. There's substantial motivic development and virtuoso writing for the first violin. Simply put, it's typical of the quality one expects from Onslow.• String Quartet No. 20 in F major op. 46 (1832) is thoroughly excellent with a raucous "Menuetto" evocative of Beethoven's 6th Symphony, but the work probes the depth of profundity in the gloomy "Andante," one of the darkest essays I've heard from Onslow.• You can’t just have one disc of Onslow’s chamber music; not when he wrote so many fabulous pieces. Check out his other quartets, too, from Coull String Quartet and Quatuor Diotima. By all means, look into his 34 string quintets, starting with his famous “The Bullet”.What a pity that Vol. 3 of string quartets by George Onslow (1784-1853) is the last in the survey. It may just be the best of the three, including Onslow’s great early C minor quartet op. 8, and two other top-notch specimens overflowing with melody, excitement, and power. If you’re new to Onslow, this program is the perfect introduction to his variegated talents and expressive aims. The Mandelring Quartet is a spirited and persuasive team playing from the heart; three members of the quartet are siblings and their father was an Onslow scholar.The String Quartet No. 4 in C minor op. 8 (1817) is one of Onslow's greatest efforts in the genre. There’s a boldness and progressive quality in this work that compares well to Beethoven’s op. 59. Certainly the Romantic expressive language stands out, while the excellence of part-writing and formal mastery recalls Haydn and Mozart. The Chamber Music Journal insists, however, that “the sound of this quartet is very original; it does not bring to mind the music of anyone else.” In typical Onslow fashion, he opens with a somber “Largo” introduction of great import, making way for a suspenseful “Allegro agitato” of impressive thematic material; the tense modulations and minor-key struggle has an air of Don Giovanni. Onslow makes a singular decision to cast the “Adagio” in sonata form. Once again, his themes are pregnant with expression and beautiful utterances during moods of yearning. The “Minuetto” is marked by Haydnesque levity in its elegant dance, occasionally intensified with thicker tuttis and packed with exuberant fiddling from the 1st violin. With the “Presto,” Onslow flexes his muscles at toccata-writing. Fast unisons, dramatic sequences, constant motion, frequent imitative counterpoint and fugato: this is sensational stuff.The String Quartet No. 25 in B-flat major op. 50 (1834) once shared space on programs with Beethoven and Schubert in the 19th century. Onslow will get your attention with the opening “Allegro moderato,” a meaty and rhythmically pulsating movement with rockets of fast elaborate violin lines, giving the first violin a virtuoso role. Inventive motivic development is worked out in the invigorated development. Next is a highly chromatic “Scherzo,” remarkable for its quirky glissando phrases and unisons, with a striking trio of quiet tremolos and pungent harmonies. An “Andante grazioso” follows, in which a captivating motivic melody is passed on to each instrument. Onslow concentrates on mining the rhythmic pattern and motives of this melody and does so like a master.For any Onslow collector out there already familiar with many of his string quartets, know that No. 20 in F major op. 46 (1832) is a great one. It opens with a bright “Allegro,” equally elegant and passionate with attractive changes of harmony and some tremolos for dramatic effect. What stands out in this quartet is the “Andante,” perhaps Onslow’s most lugubrious creation, employing a stately lamentation against slow arpeggiated pizzicato. Expressive outbursts of tutti and a chromatic central section keep the pathos in full gear all the way. As a shocking contrast, the “Menuetto” is all loud ebullience with constant eighth notes, broken 7ths, and a trio of bagpipe droning that evokes Beethoven’s Sixth. The quartet concludes with a wild “Allegro vivace,” distinctive for its fast trotting rhythm punctuated by loud forceful chords.