I wish that full centre vocal placement was a bit more common as was done in many of the earliest quad releases. I agree that it can add to the immersive character especially if the mix is otherwise rather sparse.Ken, the answer is "It depends."
- In general, I've found that 'infinite' separation across the rears is often desirable. If the separation isn't extreme, I sometimes get rear images that can appear to be coming from the front. However...
- I have had instances where I needed to bleed front-center vocals into the rears in order to bring the vocals out a bit into the room. (Lexicon Logic7 was uncanny at doing this.) I detest front-center vocals that are reticent between (or behind) the front sound stage while the rest of the presentation is 'in your face.' That's my complaint about the Azteca quad.
- Sometimes the mix is such that I use more than 12 dB front to back if I want to really emphasize elements in the rears. On the other hand, I've had songs that are immersive by their nature, i.e. The Moody Blues The Voice. With this song, I found that my homemade 5.1 sounded better with the rears blended a bit more into the fronts to maintain its immersive character.
This is all so much fun!
As a DIY project I'm thinking of taking 5.1 (from the Oppo) and mixing it to quad with the centre fed through a joystick. With that arrangement you could pan or mix the vocal to any location that you want. Keep it front and centre or move it more into the room. You could also change settings for each listening session depending on your mood! I would also like to blend the LFE channel equally into all four channels via an adjustment pot, just to make sure that I'm not missing anything down there. I always have a few projects on the go and many more in the thought/planning stage!