
When playing the standard double horns that have existed since 1898 it was, and still is, necessary to adjust to the differing acoustical resistance which is inherent in the differing lengths of the cylindrical portion of the tubing.
Paxman have developed the dual-bore system as a solution to this problem. We have enlarged the diameter of all the F-basso cylindrical tubing, and slightly modified the layout to incorporate this feature. The result of these changes has been a considerable reduction in the resistance of the F horn, matching it to the Bb side of the instrument.
After full double and compensating double models were produced with the dual-bore system, an obvious further development was to introduce full triple and compensating triple horns with the enlarged F-basso side.