Posted by Wayne Parham on May 25, 2002 at 20:06:56

In Reply to: 4Pi Theater vs 4Pi Stage 15 & 18 posted by Paul C. on May 25, 2002 at 11:38:11:

The Theater Series four π Speaker goes deeper but has rising response in the bottom octave. Response is flat from (f3) 50Hz up, but has useful response to below 20Hz. It rises at 12dB/octave starting about 16Hz, so it can really go deep with room lift, and the slope is complementary.

Another characteristic of this loudspeaker is the midwoofer's narrowing directivity making response rise 6dB in the octave just under crossover to the tweeter. When the Theater four π speaker is placed in a room corner, then the rest of the audio range is forced into approximately the same directivity pattern, and this equalizes response. Floor placement against a back wall comes close.

The midwoofer used in the Stage Series four π speaker does not have this kind of rising response. It is within 3dB (+/-1.5dB) from (f3) 50Hz clear up to the crossover point. The collapsing DI of the midwoofer nearly matches the tweeter at the crossover point, but it does not have rising response on-axis. This is because the midwoofer has falling power response that is roughly equal to its rising DI.

The Stage four π speaker sounds more natural in large spaces. If it radiates into a constrained space, the bass will be over-emphasized. So when used in smaller rooms, this speaker sounds best a foot or two from room boundaries. It is best used radiating into half-space, maybe quarter-space but eighth-space is too much.