Originally Posted by notnyt
Anechoic chambers still have LF gain. There's likely less LF gain in my room than in the chamber the M2 was measured in. The room/position the 4722 was measured in is actually down at 20hz.
The point was to show the knees of the speakers. Calling the 4722 anemic in the bass department is absurd. The M2 rolls off a couple hz lower, and more gradually due to the tuning. Not arguing that bit, just the rest of it. The M2 tunings have almost a 5db boost at 21hz, but I wouldn't expect that to exactly play loud or sound good as it's below the tune of the enclosure. At lower levels it may be acceptable.
Whoa . . . Let's make a few things clear so that we are comparing apples with apples.
1. Anechoic chambers (all the ones I have ever used) were calibrated at low frequencies, using reference measurements on a 10 m tower or ground plane. There is no "room gain".
2. Most chambers are 4pi (total free field). The M2, being a studio monitor speaker was measured in a 4 pi calibrated chamber, as are (or should be) all studio monitor and domestic loudspeakers, as defined by ANSI/CTA 2034.
3. Cinema speakers are often mounted in screen baffle walls or against walls and JBL Pro has typically measured these in 2pi - anechoic half space, possibly on the flat roof test facility. This of course includes the boundary gain and shows a different bass response than that for the M2 which was measured in the calibrated 4 pi chamber.
3. The 4722 is a screen-channel cinema speaker. Its target performance is defined by SMPTE ST202: the X-curve. This requires a flattish steady-state room curve down to 50 Hz with rolloff below that. The LFE channel is expected to provide lower frequencies. What happens in a domestic room is, well, whatever happens.
4. The M2 was designed as a "full range" studio monitor speaker, with a wider target bandwidth and a wider dispersion - a different animal.
FYI here is the X curve. As discussed in Chapter 11 of the 3rd edition, it is not the right target.