I have studied Haydn’s String quartets Op.20 which are composed in1772, for the strength and expression marks. Mozart composed his 13 early quartets around 1772.
Music source is HN9208 by Henle Verlag.
I was surprised at the variety of expression marks by Haydn himself that I thought many of them, like ff, poco forte, are by editors of posterity. I feel like those detailed indications show the strong interest and fondness of Haydn for String Quartet because Haydn established a new style of string quartets by this Op.20.
| Composer | Title | Op. | Strength Marks | Expression Marks |
| Haydn | String Quartet f-moll | 20-5 | f, poco f, p, pp, fz, | poco piano, crescendo, pianiss., sotto voce, cresc. piano assai, piano, staccato, ' , per figuram retardanionis, sempre sotto voce, |
| Haydn | String Quartet A-dur | 20-6 | f, p, pp, | pianiss. sempre staccato, sempre sotto voce, |
| Haydn | String Quartet C-dur | 20-3 | ff, f, p, fz | mezzo forte, piano, pianis. piano assai, piu forte, sotto voce, |
| Haydn | String Quartet g-moll | 20-2 | ff, f, p, pp, fz, | fortiss, sopra una corda, poco piano, piano, pianiss. con forza, perdendosi, sotto voce, |
| Haydn | String Quartet D-dur | 20-4 | ff, f, p, pp, fz | piano, pianiss., forte |
| Haydn | String Quartet Es-dur | 20-1 | ff, f, p, rinf, fz | mezza voce, pianiss. |