Cover doesn't copy — it reinterprets. And Suno's string brain loves rhythmic ostinatos, so when you feed it a quartet, it 'helpfully' adds pulsing patterns that were never there. You have to explicitly forbid the interpretation.
1. Name what you want, forbid what you don't — in the Cover prompt itself:
string quartet, sustained legato strings, long bowed notes, slow and expressive
And in Exclude: ostinato, rhythmic pulsing, pizzicato patterns, staccato rhythms
2. Describe the bowing. Words like legato, sustained, long bow strokes, adagio push toward held notes. Words like driving, rhythmic, energetic — even elsewhere in the prompt — invite the ostinato back in. Check your full prompt for rhythm words.
3. Lower the reinterpretation. If there's a style-influence/variety control, keep it low for Cover work. High settings tell Suno to get creative, and 'creative' for strings means ostinato.
4. If the ostinato is only in one section, Replace Section on that part with [sustained legato strings, no rhythmic pattern] rather than re-running the whole Cover.
The general Cover rule: it always adds its own ideas unless you explicitly fence it in. Assume Cover will improvise and prompt defensively.
Good luck! Hank founder of SonorixPG