I'm currently working through my ZX Spectrum build. I have the boxes built and am sketching out how I want to finish them. I ordered the kit from Meniscus but opted for Paul Carmody's 30 liter box design as opposed to the design from the instructions. A link to the gallery http://imgur.com/a/f1jIF
I am currently having issues as the speakers have 0 bass unless I crank the EQ from my receiver to full blast on the bass side. I've tested the woofers with a battery to verify that they are both in phase with each other and they do work. I have a large set of old Pioneer speakers in the room and the bass is normal sounding with those, while the ZXs currently have the bass response of a clock radio. This week I'll be working on debugging the bass issue. If anyone has suggestions, let me know.
** Update ** After playing for a bit, adding some polyfill and messing with the amp they have rounded out a bit, but are still very weak on the bass end. Much better than the clock radio, but not up to par for a decent set of bookshelf speakers, let alone small towers. If I turn the bass setting up to 8 (db?) then they sound much better.
Paul's design had an air core inductor for the woofer section while the kit came with an iron core inductor, I can't imagine this would make a huge difference but would it be advisable to change to the air core?