How about this for an idea for an OB7 Center speaker.
I actually have a picture but I can't find a way to upload it so it can be included in the message, maybe someone could explain how to do it.
The gist is to mount the 4 mid woofers sideways and then mount the open baffle section sideways just above the midwoofers, mounted by three rods a few inches in length between the open baffle section and the front baffle of the mid woofers. Assumes using a separate sub.