An in-depth review and teardown by Brian Klug of Anandtech has revealed that modifications quietly made by Apple to the two devices result, in some cases, in a significant boost to signal strength and range.
In addition to increased power output, Apple appears to have switched from Marvell WLAN cards to the Broadcom BCM4331, which is the same single chip solution found in the Early 2011 MacBook Pro. Another difference between the fifth-generation Airport Extreme and the previous generation is the inclusion of "finger-stock EMI gaskets" around the metal tray inside the device.
Klug's extensive wireless performance tests on the new Airport Extreme showed modest improvement in received signal strength, with the difference being more visible on the 2.4GHz range than 5 GHz. A Modulation Coding Scheme test, which "shows how fast the card is connecting to the 802.11n network," revealed "massive increases" in performance for locations farther away from the base station.
File transfer tests showed substantial improvements to downstream speeds in more remote locations, and dramatic gains to upstream performance across the board. Upstream throughput "is almost always over double, thanks probably in part to the better front end and receive sensitivity of the Airport Extremes new wireless stack," Klug noted.
Running the Iperf test showed a significant increase for the 2011 MacBook Pro, which features a BCM4331 wireless card with support for 3x3:3, and boosts to challenging RF scenarios for the 2010 MacBook Pro, which has the BCM4322 and 2x2:2.
"At the end of the day, the new Airport Extreme dramatically improves throughput in the best case and in a few regions where signal was previously unusable. In the worst case [the Kitchen], performance improves from being essentially unusable to totally fine, and in the case of the [2010 MacBook Pro] goes from not being able to connect at all to pushing 23 Mbps," Klug concluded.
For the fourth-generation Time Capsule, the publication ran just a few tests to compare performance against the fifth-generation Airport Extreme. According to the report, the two devices should have similar performance, as any differences detected in the tests were "minuscule."
The FCC provided an early look at the refreshed AirPort Extreme ahead of its release. The filings with the agency indicated that Apple had increased the power output of the device by as much as 2.8 times.
Apple quietly updated its Airport Extreme and Time Capsule products in late June, providing no mention of any changes to the hardware other than a capacity bump to 3TB for the Time Capsule.