Warning: This is 3.0 Edition material. It is possible that there is more recent 3.5 Edition version.
Inaccurate?

Fine-tuning

(Song and Silence: A Guidebook to Bards and Rogues)

Transmutation
Level: Bard 0,
Components: V, S, AF,
Casting Time: 1 round
Range: Touch
Target: One instrument
Duration: 1 minute per level
Saving Throw: None
Spell Resistance: Yes (harmless)

This spell enables the caster to make an ordinary instrument perform as if it were of masterwork quality.
For the duration of the spell, the instrument grants the user a +2 circumstance bonus on Perform checks, or an alternate effect as described in Chapter 3 for that instrument type, if desired.
Fine-tuning has no effect if cast upon an instrument already of masterwork quality.
Focus: The target of the spell.