Format Y - H is the same of Y-8 format but requires an hypercardioid mic instead of a figure 8 for the surround channel. Even if the placement is similar the 2 techniques have different encoding settings and they are very different.
Purpose: The Y format provides 4 channel
of Surround encoding on 360° degrees.
Input 3 and 4 are linked out of phase and at 1/4 level more comparing L and R.
-Advantages: Stereo encoding (DAT etc.)
-Compatibilty: Stereo and around 1/2 of the level in mono for the surround channel on axis. Good 5.1 ready to encode.
-Disadvantages: Little lossy of the surround image in mono. You may anyway compensate in post pro.
Position: The same as format Y-8