patrick eggle milan v

[gtgtgt]

This 5 string bass has a very high action. The neck is through the body. I have the bridge as low as I can get. How can I lower the action.

Must be stupid this bass is a bolt non neck which is straight when no strings on but bows slightly when under tension. Any help out there I don't have a tool to adjust the truss rod

 

[Manton Customs]

Difficult with a neck through, two options would be replacing the bridge with a lower one, or having a luthier recess the bridge into the body. Is the action high consistently a long all frets? Or is it lower/higher in places (eg, nut, last fret, middle)