With a dipole you can hear the front and back at the same time, unfortunately they are out of phase, hence the bass rolloff.

You're going to get all sorts of effects from reflections, regardless of speaker technology, but the bass cancellation of a dipole is a distinct phenomenon directly related to the minimum speaker dimension. Quad put a resistor/capacitor in the input circuitry of the speaker to help compensate. It's tempting to remove this ugly large non-polarised electrolytic and make a small active equaliser box to go between pre and power to do the same. Something like Kef used to do.

Paul