Hi alphaiii, thanks for your inquiry. Basically any dipole speaker (whether dynamic driver, electrostatic, planar-ribbon, etc.) that attempts to reproduce low frequencies will experience some cancellation of said frequencies unless the two indentical out of phase waves can be kept from summing in free air; this is one reason why you must put a moving coil woofer into an enclosure to get better bass performance. Thus, the 5DB in dipole operation will experience this cancellation in the bass frequencies. Of course, the 5DB has many other benefits to it that make it a fine speaker and will actually play a smidge lower in the bass when in bipole mode. But due to our desire for the enclosure to be a manageable size, and the fact that there's usually no bass information in the surround channels anyway, the 5DB proves more than sufficient for a typical surround setup.
Lastly, since the 4BP is a sealed bipole speaker with a single woofer, there's no possibility of two out of phase waves–only in phase waves in the treble region.
I'm looking to upgrade my home theater with new center, surround, and rear surround speakers. Due to limited budget, I'm considering the 4C center, and 4b's for surround and rear. However, what difference would the 4BP make as side surrounds? Would there be a noticeable difference from the 4B's and in what way?
Mark, thanks for your input. Since my post I've been doing some additional reading on the forum and it seems there are some strong recommendations to get a good center channel speaker, especially for movies, which I frequently watch. Since I don't have the budget for both the 4BPs and an upgrade to the 5C, I'm thinking of sticking with the 4B's for the 4 surrounds and the 5C center. What do you think? The main thing I am looking for is a upgrade to sonically compatible home theater setup, as opposed to my current rag tag mixture of speakers.