Progressive Transition (PT) Waveguides
Balanced frequency response, pattern control, and distortion, improved sound reproduction.
Progressive Transition Waveguides provide excellent coverage control and are rotatable so the loudspeaker system can be used in either the vertical or horizontal orientation.

An Introduction to
Progressive Transition Waveguides:
The modern constant-directivity horn has evolved slowly since its introduction over 25 years ago. Advances in horn design have been primary evolutionary in nature. To achieve balanced response of all parameters, JBL Professional started with a clean sheet of paper and developed Progressive Transition (PT) Waveguides.

Progressive Transition waveguides are unique because a single mathematically-continuous surface defines the waveguide from transducer- throat to waveguide-mouth. The distinctive feature is the lack of a traditional diffraction slot. Instead the sidewalls transition smoothly from the driver throat through to the square or rectangular mounting flange.
Progressive Transition Waveguide Families
PT waveguides are grouped into two families. The first is “compact”, and second is “optimized cover- age/rotatable”. Compact PT waveguides balance performance in favor of small overall package size. Frequency response is optimal, distortion is superbly low, depth is minimized for use where a shallow enclo- sure is required. Beamwidth and directivity are optimal in the horizontal plane. Vertical beamwidth and directivity are optimized to provide a good match with JBL low frequency and midrange transducers; however, vertical pattern control does not extend as low as optimized coverage PT waveguides.