The original design was a bookshelf, but you've built a floor stander. How can the volume be the same?
The boxes are different shapes, but the same volume (22 l), same baffle width, same port configuration. No solid dividers, though that would work too.
Inside of the original design is 6 x 19 x 12.75; floorstander is 6 x 34 x 7. After accounting for differences in bracing, they are very close. In fact, I arrived at the dimensions I used so that their volume would match the original design and put the tweeter at a reasonable height.
I also doubled the depth of the front baffle to stiffen it and to move the driver further from the rear wall, which is a bit close in the floorstander (I added additional stuffing to help with this).
I hope that makes sense.
