Magnepan vs B&W: Same specs, different bass?

I've also A-B'd the Magnepan 3.7's to my of Thiel CS-2.4's which have these specs:
Frequency response: 36Hz–25kHz, ±2dB.

Thiels are similar to the B&W's and blow the Magnepans away with regards to bass, trying to figure out why when the specs are so similar.

There might be other reasons, but isn’t Magnepan’s 35Hz-40kHz a -6dB range, related to 1kHz (I assume)?

±3dB is frequency response (flatness) while -6dB is frequency range (related to something, usually 1kHz)

Also Magnepans should be pulled many feet from the wall, due to their dipolar nature, to avoid bass cancellation.  The difference you're hearing might be the room response.

I have owned and listened to the 6 foot Magnepans every day since 1977.

The .7 series designed under Mark, son of the founder Jim Winey, simply does not go as low in the bass as the previous 3 series.  That is my experience having heard the new .7 and .7i 6 footers in stores and in homes.

The .7 spec is a frequency range without any +/- dB listed.

The actual bass response is determined by the quality of the power amp, room setup and size of room.

The IIIa has the largest bass panel, and had a claimed spec of 32 to 40Kz +/- 4 dB.

I have heard all the 6 foot 3 series, and the IIIa goes noticeably lower than the others.

I have measured flat response down to 30 Hz with my IIIa, and 33 Hz with my 3.6 in various rooms.

I use the 3.6 in my living room and IIIa in my home theater currently.
 

As Kijanki said, speaker placement is responsible for the aparant differences you hear.

Maggie’s require lots of space compared to more conventional speaker types. The placement from the back wall and sidewalls is critical for optimal performance

Regards

I agree with Kijanki and Williewonka, that its probably placement of the speakers in relation to the size of the room. Maggies can get low and punchy sounding when set up in the right room correctly.

Matt M