The back-to-back dome tweeter used in typical dipole setup is the achiless heel of the system. The on and off-axis frequency response is not smooth.
Many diy-ers investigated alternative approaches for the problem. Basically to keep uniform dipole radiation to very high frequencies, the baffle needs to be either very small or naked drivers are used. Having a pair of Tangband fullrange speakers I experimented with them.
The resulting result is smooth polar response up to 10khz.
While it looked promising, after a while I felt the whole system did not sound coherent. I have not understood the reasons behind it but it is perhaps due to:
- The transition of baffle size
- The fullrange driver unable to deliver the resolution required for high frequencies
I have sinced moved back from this design. The full investigation can be read here.