Flat frequency response and a consistent cardioid polar pattern make the CK 91 an ideal tool for applications where good off-axis rejection is required.
The AKG Blue Line Series consists of a family of directional prepolarized condenser capsules and microphone configurations that are all compatible with a single powering/output assembly. Because of the general popularity of the cardioid pattern, the CK 91 cardioid capsule and SE 300 B powering/output assembly are sold as a single unit, the AKG Model C 391 B microphone. The remaining Blue Line capsules offer the following patterns: CK 92 (omnidirectional), CK 93 (hypercardioid), CK 94 (bidirectional), and CK 98 (shotgun capsule, high directivity). Three additional configurations are available: CK 97-O (omnidirectional lavalier), CK 97-C (cardioid lavalier), CK 97-CVR (cardioid gooseneck with bass roll-off). The Blue Line Series is suitable for studio, live sound, and a variety of speech reinforcement applications, where the facility for switching capsules is a major advantage. The positive Modulock™ bayonet design allows these changes to be made quickly. The Blue Line microphones exhibit accurate axial response and uniform pattern control. Self noise and maximum operating levels are exemplary, creating a very wide usable dynamic range for the most demanding operations. The SE 300 B powering/ output assembly provides for 10 dB of attenuation for operation at high sound pressure levels, as well as a 12 dB/octave low cut below 75 Hz for close usage. A complete line of optional accessories is available including an extension cable for operating the microphone capsule up to 10 ft. (3 meters) from the powering/output module.