1) Dipoles and bipoles are extremely different things. An acoustically small dipole has 4.8dB of directivity which means it's radiating 1/3 the total power of an omnipole for a given on-axis SPL. A bipole tries to approximate a monopole with 0dB of directivity.
2) Most "dipole" speakers are planers which are not acoustically small at higher frequencies and don't do a good job approximating an acoustic dipole with directivity breaking 10dB at high frequencies and all sorts of lobing that make for a narrow sweet spot for both imaging and correct tonality. You need to differentiate between those and speakers which act more like dipoles. Panel resonances are also an issue.
3) Conventional wisdom which holds that dipoles add more reflected energy to the sound than conventional speakers is incorrect. A conventional speaker starts off omnidirectional with 0dB and has directivity increasing with frequency to perhaps 10dB at the end of it's tweeter's pass-band. It generally doesn't surpass the dipole's directivity until 1-2KHz which we could approximate as the end of the human vocal range.
That's because although dipoles have more energy headed out the back they have less to the sides (-3dB at 45 degrees, -6dB at 60, -12dB at 75, etc.) which is friendlier for many listening rooms. When I eyeballed the numbers for one listening room I noted a 7ms delay for the front wall reflection that was -6dB for distance, 4ms off the ceiling at -3.5dB, and 3.5ms at -3dB for the side wall. Mix in dipole attenuation of -3.7dB off the front wall, -3dB off the ceiling, and -8.2dB off the side wall and it's obvious the dipole can color the sound less than a conventional speaker.
Using a decent dipole implementation (not a planer) you still get whatever sound stage is recorded without embelishments. You can use the off-axis roll-off to compensate for speaker distance as you move off one side so you can have an imaging sweet spot for several people. You also get no bass boost below the room's fundamental resonance and better modal behavior.
It works _spectacularly_ well for critical listening.
2) Most "dipole" speakers are planers which are not acoustically small at higher frequencies and don't do a good job approximating an acoustic dipole with directivity breaking 10dB at high frequencies and all sorts of lobing that make for a narrow sweet spot for both imaging and correct tonality. You need to differentiate between those and speakers which act more like dipoles. Panel resonances are also an issue.
3) Conventional wisdom which holds that dipoles add more reflected energy to the sound than conventional speakers is incorrect. A conventional speaker starts off omnidirectional with 0dB and has directivity increasing with frequency to perhaps 10dB at the end of it's tweeter's pass-band. It generally doesn't surpass the dipole's directivity until 1-2KHz which we could approximate as the end of the human vocal range.
That's because although dipoles have more energy headed out the back they have less to the sides (-3dB at 45 degrees, -6dB at 60, -12dB at 75, etc.) which is friendlier for many listening rooms. When I eyeballed the numbers for one listening room I noted a 7ms delay for the front wall reflection that was -6dB for distance, 4ms off the ceiling at -3.5dB, and 3.5ms at -3dB for the side wall. Mix in dipole attenuation of -3.7dB off the front wall, -3dB off the ceiling, and -8.2dB off the side wall and it's obvious the dipole can color the sound less than a conventional speaker.
Using a decent dipole implementation (not a planer) you still get whatever sound stage is recorded without embelishments. You can use the off-axis roll-off to compensate for speaker distance as you move off one side so you can have an imaging sweet spot for several people. You also get no bass boost below the room's fundamental resonance and better modal behavior.
It works _spectacularly_ well for critical listening.