It's true, bridging does not change the speaker's impedance
but since each channel of a bridged amp drives half the wave form, it sees half the speaker's impedance. Most manufacturers of 4 ohm (or less) speakers advise against bridging. However, some amps will drve any load so it is best to check with the amp manufaturer.
but since each channel of a bridged amp drives half the wave form, it sees half the speaker's impedance. Most manufacturers of 4 ohm (or less) speakers advise against bridging. However, some amps will drve any load so it is best to check with the amp manufaturer.