Microsoft has released its second test build of its Windows 10 "Redstone 2" test build in the past two weeks -- and the first for Windows 10 Mobile.

Build 14905 is available to Windows 10 Insiders for PCs, tablets, and select Windows Phones as of August 17. As was the case with 14902, the previous Redstone 2 test build released last week, most of the work in this test build is under-the-covers work happening around OneCore, the common shared Windows 10 core that will work on all variants of Windows 10.

Build 14905 does include "a newly refined sound set." It also includes several fixes for PC, including one affecting Edge browser spacing.

The full list of fixes, improvements, and gotchas for both PC and mobile users is in Microsoft's blog post on 14905. Given this is an early preview build, a number of features aren't working with this build, so make sure you know before you install.

In other Windows 10 update news, Microsoft quietly released a new Cumulative Update, Build 14393.82 only to testers in the slowest test ring, the Release Preview group.

This is not a Redstone 2 build; it's an update to Windows 10 Anniversary RTM (release to mainstream), And this update didn't go to other groups of testers, like Fast or Slow Ring testers. Microsoft has not disclosed the new features or fixes in 14393.82.