There seems to be a weird trope that features the repeated I, I7, IV, V progression over a root bass.
Examples
- Haydn Op. 9, No. 2 in E flat major, first movement
- Haydn Op. 50, No. 3 in E flat major, first movement
- Haydn Op. 71, No. 3 in E flat major, first movement
- Dittersdorf String Quartet No. 5 in E flat major, first movement
- Beethoven String Quartet No. 12 in E flat major "Arpa", first movement
- Boccherini String Quartet Op. 1/2 No. 4 in E flat major, first movement
- Spohr String Quartet Op. 152 in E flat major, first movement
What I find concerning is that all String quartet examples are
- In E flat major
- In the first movement, near the beginning (excluding introduction)
- Repeat the progression
- Are played over a held E flat bass
Almost matches
- Schumann Piano Quintet in E flat major, first movement
- Spohr Op. 15, No. 1 in E flat major, Db only in second repeat
- Spohr Op. 83 "Quatuor Brilliant No. 5" in E flat major, no Db, but same vibe
- Arriaga String Quartet No. 3 in E flat major, no Db
Here's my best explanation for why this is happening
- E flat major is a good key for string quartets
- The I, I7, IV, V (repeated) over a root bass is a good way to destabilize the key and transitions well to the B theme or the development (which explains when this trope is found)
- Due to seeing this trope, I am more likely to notice this trope if the key is E flat major, I just haven't noticed it in other keys.
- If it were in another key, I might not notice it because I implicitly associate this trope with the particular register and timbre of a string quartet in E flat major. (I do not have absolute pitch in case that's relevant).
For the sake of my sanity, please find me a counterexample that is not in the key of E flat major or else I'll go crazy.