AndrewA's ES5-V

[Simon Barden]

I would imagine it's a T-piece in the PB kits because the top is normally drilled for a tune-o-matic bridge, so needs a wide block under the bridge area to take the post holes. It's probably then just easier for the factory to use the same sized wood to make the rest of the post. It certainly isn't placed properly to tune the acoustic response. Maybe it is simply there for some added structural support, or maybe it increases the sound level at which the body starts to resonate and goes into feedback.

[stan]

I would imagine it's a T-piece in the PB kits because the top is normally drilled for a tune-o-matic bridge, so needs a wide block under the bridge area to take the post holes. It's probably then just easier for the factory to use the same sized wood to make the rest of the post. It certainly isn't placed properly to tune the acoustic response. Maybe it is simply there for some added structural support, or maybe it increases the sound level at which the body starts to resonate and goes into feedback.

I agree Simon, I think this is purely for bridge support rather than any type of sound / resonance transfer.
I have a Harmony archtop with very similar construction. It has a floating bridge, and no such support. It has two parallel supports that run the length of the top at about the same width as the bridge