Cardioid loudspeakers have desirable traits when place in a room. However they are normally difficult to design and build.
Using S19 platform two alternating channels are converted to monopoles, which provides the acoustic sum as Cardioid.
Follow the build discussions here at DIYAudio.
Outdoor polar response measurement result (7/9/14)
20khz - 800hz
800hz - 50hz
- The perfect Cardioid was never formed fully
- Forward directivity is maintain from 20khz down to 600hz. -6db less rear radiation or better.
- Then it transtition to a weak dipole to Omni. The transition is smooth and not abrupt.