It's all good Simon. Building the half Imperial was a cinch compared to the
                       IMPERIAL.
It's just so darn big, not the sort of thing us amateurs can slap together
in couple of hours, or do a little bit and then put the item back in the
drawer till next week. It took me months to complete two Imperials,
mainly because I would have to organise a spare pair of hands for the
heavy bits.

Where am I going to put the horn? Hey buddy, notice it's still on the patio
(with the woofers  :D)

Cheers

Gaz

Hi Henry,
If you want some more data about the Half Imperial, I will gladly send the numbers. As I am always quick to point out, the Half Imperial (and the full Imperials for that matter), where built on the cheap, I can only imagine just how they would sound using premium materials. Just wondering if I'm in breach of rules if I 'publish' the measurements ??? which after all are not exactly 'half', but certain elements are Steve's design. i.e. buy Steve's plans and what comes off the saw is yours  :)
Gaz

It would be helpful if you purchased Steve's plans. The various angles, shape and size of the horn (but ~1/2 width) are identical to the Full Imperial. My major detour being the use of 18mm particle board, the heavy stuff used for flooring. I think I've got the 18mm/19mm original ply conversion sorted. This is where I can be of some help. Just need to run a tape measure to give you overall h x w x d type stuff.
Gaz

I'll get the tape maeasure ready!

Hiya Henry,
I'll get back to you shortly. Firstly though, what grade (thickness) wood are you planning on using. That is the major concern when figuring out height and depth issues. As you see, the Imperial plans are for 3/4" (19mm) ply.
Gaz

Then thats easy. For height and depth, you cut the wood as per Steve's plans. The width is the only modifier, which in my case, is a whisker less than half. (Can get exact measurement). I guess the only other factors which might alter tonality and response is the amount and type of filler you put in the speaker chamber - of which I used very little. One thing I never got around to doing was stiffening the front face of the speaker baffle. I figure that may help sound even better = less extraneous vibrations imparted to the drivers.
As a starter, measure out (even using newspaper) a fullsize template of the front face of the 1/2 Imperial approx 6ft tall x 1.5ft wide to give you a good idea of what to expect. Will it fit in your room, ht, back seat of your vehicle  ;D

The baffle chamber size and shape are exact to the plans, other than the width of course. The baffle chamber, being one of the trickiest components, may well be one of the first pieces to build.
By the way, what do you reckon of the full sized Imperial plans? When I finally got my head around what I was seeing, I was amazed. I printed out the plans on A3 paper, in colour. Made things much clearer. Errr, my smilies don't seem to be working?