Hi Scar
Well sir you have asked a very important question and one that has been rampant for decades. The concept of a 'radiating sphere' where the polar response of the speaker is flat and even in every direction has long been the goal of many speaker manufacturers. One driver handling the full frequency response and able to radiate its energy in a perfect circle (sphere) both horizontally and vertically has been the lofty goal of many.
So the different speaker designs to some degree attempt to approach this goal in a variety of ways. Omni speakers (drivers front and rear typically) are the closest to this goal in theory but getting the right balance (Power Response) into real rooms has been a challenge and optimizing driver arrays to have equal radiation in every direction is very difficult to achieve. So Dipoles, Bipoles, omnis, direct radiators etc. are all attempts to optimize the power response and frequency balance in typical rooms with typical dimensions.
The new Axioms are probably the closest at doing this now for a number of reasons. One of the issues that has arisen is that if the rear wave is equal in volume level to the front wave it tends to make the speaker sound too bright in most environments. It is one of the issues bipoles and dipoles have to address and in many of these designs the rear wave is attenuated a bit to account for this in the internal passive crossover. In the new Axiom they control this rear wave set of drivers using specific electronics rather than passive components in the loudspeaker. So the radiation pattern is adjusted at the preamp level and forwarded to the power amps (you need 4 channels with the Axiom). The advantage of this approach is you can now easily control the rear radiation pattern electronically independent of the front radiation pattern whereas in a passive system this is not possible with the same precision.
With a direct radiator like the Model T it is a more conventional approach and the radiation pattern is more forward into the room as there are no drivers on the rear of the speaker. We believe though that the radiation pattern even in the forward direction should be as wide and even as possible in both the vertical and horizontal planes. The Power Response on the Model T is as accurate as can be accomplished in today’s designs and I am very proud of what we have achieved with all the Bryston speakers in this regard.
So with that background choosing the right speaker for you’re application is definitely something to consider. The complexity of the setup, the rear wall symmetry, the electronic necessities, number of amplifier channels, type of soundstage required etc. all enter into the equation.
Hope this helps.
James
