Because the crossover frequency between the subs and the mid-woofers on my three front speakers is set at 200 Hz, in order to limit resistance in series with the subwoofer drivers with an inductor, I opted to use active bi-amplification. Had I used a higher filter point , let's say 400 Hz which is unrealistic with a sub driver, I would have built a passive filtering circuit. However, I am using a passive crossover between the mid-bass drivers and the tweeters.
While using active bi-amplification with a high frequency driver or a tweeter, it is recommended to put a capacitor in series with the HF driver to protect it from any unexpected low frequency input or DC offset, but without impacting on its projected frequency response.
