Initial publicity on "The Vibe" seemed to suggest that it would be available on an HD-2 subchannel; however checking just now there is no HD on KTSU. The station did broadcast in HD a few years back, so perhaps that will return.
KTSU also has "KTSU2 The Voice" which has been online only. If they relaunch HD perhaps that would be on the HD-2 and "The Vibe" on HD-3.