Hi, I have white frets on my BV9 and BL5s - they simply need regular, gentle cleaning with a vacuum cleaner on low suction with a brush attachment. Just remember, the white just makes the dirt more visible, so if you have black frets, they are likely just as dirty, but you donβt notice it! π
Another point is, if you do decide to re-cover the speakers, choose the fabric carefully. Through the white fret on my BV9 I can see the holes for the speakers, whereas on the BL5s they are less obvious. You need to balance acoustic and visual transparency.
Lawrence